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Internal Combustion Engine (ciechanow.ski)
2333 points by algui91 on April 30, 2021 | hide | past | favorite | 392 comments

A few thoughts while reading this:

In addition to a deeper understanding of engine manufacturing considerations than I even knew I cared to learn, this article helps me appreciate why people are into engine work.

The perfect tolerances and synchronization of these machines makes me a little ashamed to use the word "engineer" in my title of "software engineer". There is no real comparison of the quality of the result.

And then I skimmed the source, and it makes me think the author deserves that title. It also validates my belief in vanilla javascript.

edit: And later it occurs to me that Mr. Ciechanowski is a true craftsman of software; handmade and built to 1) Be beautiful (and informative), 2) last for years. (The open web standards are the ones that seem to stick around the longest, for better or for worse. (I'm ignorant of the shader world though))

> makes me a little ashamed to use the word "engineer" in my title of "software engineer". There is no real comparison of the quality of the result.

I think that's because the barrier to entry is too low and anybody is being called a "software engineer" these days.

But think about a system which makes proper use of synchronization primitives, like an OS kernel or a robotic control, or a CPU design like the other guy commented too, or maybe a 3D game with tricks like that of John Carmack. Those things can be as complex as an ICU engine.

To make an analogy: in the physical world there are the engineers, and the mechanics.

In the software world everybody is a software engineer.

When I took "Software Engineering" in University, the prof was very careful to explain in great detail, and frequently, that the field was not mature enough to really be called engineering. Then he would talk at length about things like software for airplanes and spacecraft. It is impossible to call yourself an engineer while looking someone in the eye after taking his class. I am a software developer. Maybe an analyst. But mostly a developer.

The word engineer is used by anyone who 1) has an engineering degree or 2) works a field where most new practitioners have such a degree. Most of these people don't know shit, and design terrible systems that barely work (or don't work at all). Trying to elevate the word to a non-existent Plutonic ideal where it means "great engineering" is just ... pointless and faux-humble.

Real engineers are like doctors, lawyers, LMFTs... even licensed electricians have some similarity here:

The point is, the “field” , has taken in a number of disasters, established a professional association, set standards for what you need to know to not be putting people at risk of dying, and created tests that new entrants have to pass in order to be certified with a title.

Now, you can say that is pointless bullshit—fine. That’s an opinion. But then you are just saying you think the title of “Engineer” is bullshit, we could still at least try to use the word properly.

The point is, people used to be able to use the word “Engineer” to mean something like, your house isn’t going to slide off the cliff, and your bridge you bought isn’t going to fall down, and due to “software engineers” who never bothered to set any professional standards for themselves, that word is less and less meaningful.

Words come and go, it’s not the first time. But it’s still a little bit of a bummer when it happens.

My experience with your “licensed” professionals has been terrible. They do not meet a high bar of quality, and their services are artificially expensive, and they discriminate heavily against minorities, immigrants, and the poor in their gatekeeping.

It’s also clear to me that most experienced software developers are more qualified than most “credentialed” graduates of CS/software engineering (most of whom can’t really code).

At least that's not the case in Canada. Neither of those qualify you to use the title "engineer", and if you do you are likely to get a letter warning you to stop. Those are both just prerequisites among several others.

> Those things can be as complex as an ICU engine.

From a complexity perspective an ICU isn’t nearly as complex as even something as simple is a script scraping a webpages for links and queuing them up for further crawling. I’m not sure if “complex” is the word you are going for but even the TCP state machine has significantly more complexity than an ICU and that’s just a fragment of what it takes to transmit some data.

The composability and abstractions we have in this industry allows you to quickly dwarf any regular mechanical system. There is a reason this is a whole new era beyond the industrial revolution.

Quantifying complexity really depends on the level of abstraction though.

Scraping a static webpage is simple when examined at the level of abstraction involving Python and ready made packages. An ICE is similarly simple when examined from the perspective of basic mechanics, as in the article under discussion.

As you note, scraping that static webpage is no longer simple when you include as part of your assessment the TCP state machine, kernel interface, NIC firmware, and similar layers that had previously been abstracted away. Neither is the ICE though once metallurgy, machining, oil chemistry, and the physics of combustion are included.

Granted, pursued to the logical extreme software eventually drags in everything the ICE did and more due to the physical hardware. But then modern engines are controlled by computers ...

The complexity in the engine isn't in the mechanical concepts that make it tick, it's in the implementation details. Stepping back quite some time in technology, but staying with engines:

The platonic carburetor is a dead simple device: a Venturi, a jet, and a butterfly valve. Real life carburetors are fiendishly complex: multiple jets, an accelerator pump, a choke. And god help you if you have multiple carbs on a single engine and need to sync them.

Everything that goes into making an engine work is similar: cooling it correctly and evenly, allowing for operation while parts expand and contract at different rates as the engine reaches operating temperature, lubricating everything, preventing vibrations that'll make the car feel unrefined or maybe tear the engine apart, valve timing (fixed in most engines at some compromise between performance and drivability), ignition timing (variable in most engines), sealing things that need to be sealed across a huge range of operating temperatures and in the presence of differing rates of thermal expansion (head gaskets, among others) oh, and making it work for a quarter million miles or more with fairly minimal maintenance. And manufacturing them at enormous scale, and holding the tolerances that make all of the above possible across the lifespan of the production line.

And all of that is before we even discuss pollution controls.

Nicely put! I think most "real" engineers dismissal of software engineering is because we can for the most part ignore physics. This somehow seems like cheating and not mathematical enough to be "real" engineering. I've even heard the claim that discrete mathematics, graph theory, and theoretical computer science is not "real" mathematics. It should be clear that a developing complex software system like Unix, Kubernetes, Redis is engineering, but somehow others from different engineering disciplines cannot see that. After bringing so many great inventions and innovations into this world, how can we once and for all make the case that software engineering is real engineering and get the respect that this field deserves?

Well that’s just because we understand internal combustion engines well enough that we can abstract away a lot of the details. Software engineering is nice because by design it is at a level of abstraction that we can grok it. We’re basically manipulating structural concepts of pure thought. But never forget that reality has a surprising amount of detail. When we interact with the physical world, we rely on abstractions at our peril.


I don't think you can compare both. It's abstractions all the way down, for both. Modern ICE are made from metals compounds that were unknown a few years ago and are the reason they are efficient. Just as you can send bytes over a wire without TCP, you can build an ICE from pure iron. But both then have just very low fault tolerances and break rather quickly.

I kinda wish my title was simply “Systems Administrator” which is probably the closest thing to a “software mechanic” that we have. Most of our titles have been inflated however.

Thank fuck fluff titles like "Happiness Engineer" have gone away though.

That's why I often joke that a big part of my work is as a software mechanic! Which is still highly technical and necessary but the engineering part happens less often.

I _am_ a computer scientist, but also had a course "Gasoline and Diesel engines" at university. (Belgium before Bologna)

Excuse me, but modern CPUs are way more complicated than this, even if you only look at "arranging events in time". Like several orders of magnitude more complicated. Anyone who has touched VHDL/Verilog knows how delicate signal propagation is, and how crafty you have to be with the clock.

And even if you never tinkered with transistors surely you've at least looked at assembly code, and the amount of painstakingly detailed data layout orchestration that is going on there. A simple printf("hello world") is magical if you know what happens under the hood.

It's easy to dismiss the difficulty of something when all you see is a webpage explaining things very well and simply with some cool graphics. That webpage looks really cool, but this is just a front page of the result. The backend of all the math, equations and thoughts involved wouldn't be so visually appealing. This is just the pretty part result. If you would delve into the actual math and physics that was required for this I'm pretty sure you'd reconsider that statement. Just the study of vibrations alone is probably as difficulty as whatever you're talking about. And that's just one of several areas of study that needs to be considered when making a machine like this. Then you need static mechanics, dynamic mechanics, thermodynamics, fluid mechanics, knowledge of manufacturing processes, materials, among others. And each of these topics is HUGE in itself. You probably have no idea because you're a software engineer? It's easy to defend our own realm and dismiss others, when we know little about others' or all we know is based on some cool animations we saw on the web once.

Well, Electrical and Computer Engineering is an extremely precise discipline, and while the line between hardware and software can be fuzzy in many cases, web software is an entirely different world from VLSI design, and even from instruction set design. And of course, some software, at all abstraction levels, is extremely well engineered as well. But it doesn't seem to be the norm.

Most importantly, I'm talking about my own ability more than the best in the field.

I doubt most of the readers here on HN ever wrote anything in assembly. It is like comical interaction of Marc Andreesen and Mark Zuckerberg and how Zuckerberg had no idea on the Netscape browser (let alone Mosaic or Gophers).



The vast majority of people on this site have never written a line of C or Assembly in the past 12 months

Most people who write software do not know/care how circuits work, as they shouldn't. Car engineers similarly don't need to know how bridges are built.

Correct, but it can be a fun exercise, if for nothing else than the curiosity alone. Learning basic circuit theory leads you to diodes, which then leads to transistors, which then leads to op-amps, logic gates, etc. which leads to computational logic units like the ALU, etc. Before you know it, you have a very, very basic computer going on.

Either way, it's the core process of engineering - applying theory, and breaking up complex parts into more manageable chunks. Same goes for the car engine - it's a complex piece of machinery, but still a sum of its parts.

Achievements in other disciplines can often look like magic (and some are but it usually takes experts to tell which). I think fundamentally engines are engineered like software- by solving one problem at a time. And after having gotten a distributed consensus algorithm to work with a perfect dance of elections and voting etc I feel like there is magic in software too.

I have had the same thought, software can often feel messy and unpolished. But to be fair to ourselves, we simply don't require the same tolerances in most software.

I’m a lowly mechanical engineering lecturer. I use Jupyter notebooks to teach fluid mechanics[0]. I make videos of fluid flows with Blender and embed them with the notes along with some basic Python code examples so that students are aware of how basic code can make an Engineer’s life easier (even if Matlab is the standard platform).

I also embed simple 3D models with pyGEL3D[1]. It’s fine but very limited. I’m always blown away by this gentleman’s work when it comes up here on HN and would like to use JavaScript instead, but I’ve no idea where to start. Can anyone recommend a good book or online course that would put me on the right path?

[0] https://nbviewer.jupyter.org/github/nolankucd/MEEN20010/tree...

[1] http://www2.imm.dtu.dk/projects/GEL/PyGEL/

Why do you have to learn JS? If you just want to make a web app and add some interactive 3D models on it, there're some Python libraries can help with that, like: https://github.com/streamlit/streamlit https://github.com/wang0618/PyWebIO https://github.com/plotly/dash

Why learn JS? I guess it’s because I think it’ll be a useful skill that will allow me to do more in the future, not just find a better way to embed 3D models in a notebook.

It might be useful to build tools for research projects, interactive elements for assessment etc.

The bulk of my coding is work Matlab and an increasing amount of Python. JS would allow me to to more web based stuff.

For the graphics: - https://webglfundamentals.org/ - https://threejs.org/

For general JS: - https://developer.mozilla.org/en-US/docs/Web/javascript#tuto...

There's other stuff like build tools, cross-browser, and other stuff, but that's likely to be confusing and not super necessary to begin with. The above should be enough to get you running with what it sounds like you want to do.

I appreciate you sharing those links. I'm trying to learn mechanical engineering stuff myself, if you have any further useful learning materials I would love to see them.

Much appreciated. I’ll be adding to the fluid mechanics notebook this summer.

What areas are you interested in?

Mechatronics, which is why I'm interested in mechanical engineering. I guess this mostly implies servomechanisms, kinematics, motors.

Also I would trade you mech eng tutoring for JS tutoring, if you've got the time.

I wish there were more opportunities for people to learn via “cross training” like this.

I’d love to learn more about a number of engineering disciplines by helping people who know those fields, learn how to implement the algorithms and mathematical calculations they need in Python and simultaneously, learning more about those algorithms and calculations in order to best implement them and show how best to use Python for these tasks.

But unfortunately such opportunities are few and far between outside academia and other learning oriented environments in my experience.

I love this idea. The best way to get academics to buy in would be to have some clear outcome such as a publication or funding opportunity.

There are a lot of clunky engineering tools that would benefit greatly from professional software development. Computational Fluid Dynamics software in particular is just plain awful in terms of usability for beginners.

What are the names of some of this software that are a good example of in-use but are clunky/have awful usability? I ask because it sounds like an interesting area, and I would like to see for myself what you're working with.

On one hand there is Ansys. It’s a Frankenstein’s monster of a software suite for numerical simulation comprising several tools that have been acquired over the years. It’s frightfully expensive and there’s no incentive to make it more usable as there’s limited competition.

Then there’s OpenFOAM which is a fantastic open source alternative. It’s entirely command line based but there are UI derivatives and cloud based versions (SimScale). However it’s a nightmare of disjointed code, difficult to build and heavy on dependencies. You spend all your time dealing with endless problems related to defining simple geometries in the basic BlockMesh tool and then dealing with and compiling various solvers. It’s a research grade tool and not a polished piece of software. I won’t go into the various versions with incompatible differences.

Getting the most basic stuff working is tedious and frustrating in both.

After a few years of this masochism you just get on with it. However, when you are trying to guide students through the software for their final year project they spend about two thirds of their time just figuring out how to get something simple running and then never want to touch CFD ever again.

Then there’s Blender where I can install it in seconds and set up a simple flow simulation with a straightforward workflow. Sure the result is not remotely accurate but that’s just the solver, there is no reason for the complexity of the workflow in Ansys or OpenFOAM other than it was designed by (Mechanical) Engineers who know nothing about good software design.

Thanks for the info! Heh, if Blender is your only go to alternative for ease of simulations and usability, then there's definitely a need for improvement.

The speed and efficiency of Blender at creating geometry and timing animation is incredible. Doing mostly the same stuff in the aforementioned CFD tools is incredibly convoluted in comparison. It’s like trying to code in MS Word whereas Blender is like Vim.

What’s this time you speak of?

(new Date()).toLocaleString()

I guess the person you replied to is saying that they are interested in teaching you JS, in exchange for you teaching them mechanical engineering fundamentals, assuming your schedule can allow that.

I got that, I have very little free time and I’m in Ireland so I’ve no idea how time zones would permit this.

My response was meant to be humorous.

as was mine (I'm in CEST timezone, fwiw)

And my guess is the reply means: ”there is no time, but I wish...”

I recommend trying to get started with webGL Elm [0]. It's a language that compiles to JS to run in the browser. It's a functional language and saves you from having to deal with most of the historical baggage of JS.

[0] https://lucamug.medium.com/3d-graphics-in-the-browser-with-e...

There's an array of javascript libraries to choose from, but maybe you would find Observable (reactive javascript notebooks) to be a good substitute for Jupyter.

Observable is geared toward the use of d3.js (essentially a library for drawing charts and graphs) which can be a bit intimidating, but you can use other libraries as well. For 3D, regl seems to be a good option. It's a library which makes using WebGL a bit more convenient. Here's an example of an Observable notebook that uses regl: https://observablehq.com/@rreusser/contour-plots-with-d3-reg...

Check out R. Reusser's other notebooks too. My guess is that choosing a set of JS libraries/tools to learn is the hard part, here, once you've committed to javascript.


Thanks, I’ll take a look.

I use Jupyter because it’s something that the students are finding used more and more when they go on industrial placement. Matlab is extremely popular in engineering but Python is growing.

My notebooks are deliberately simple so it’s not I ntimidating for students who are frequently terrified by code. The point is to show them that some basic readable code can help them solve problems and avoid going too deep into the weeds.

I'm on mobile so linking is a bit of a schlep.

1. MDN is a good starting point to learn Javascript.

2.Then the three.js library for 3D in the browser.

3. Maybe P5.js as well for 2D.

One of those web pages which deserves an award. Some place in some kind of Internet Hall of Fame, an historical archive which shows the only best highlights of what websites were actually capable of presenting. Milestones of web development.

This page summarizes pretty good what web technology is capable of, when in the hands of a real professional.


Ok, I just realized this is from Bartosz Ciechanowski, and this reminded me of the Cameras and Lenses [1] article which I've seen recently. It was the same kind of quality.

This man is a real genius.

[1] https://ciechanow.ski/cameras-and-lenses/

I'm assuming he used something like SolidWorks to CAD up the parts, but then it looks like he custom made all the animation stepping widgets and camera rotation logic and various shaders for the different effects in pure JS[0]? Surely he didn't write this JS by hand (i.e. it was generated from blender3d or solidworks files or something?).

I would like an article on how he made the interactive animations in the article.

[0] https://ciechanow.ski/js/ice.js

I think it can't be understated how important it is to able to rotate, and move the playback forwards and backwards.

It's almost like being able to hold the part in your hands, examine the reasoning behind its structure and "debug" your mental model of it by playing its operation back and forth.

Exactly, having control over the artifact is so empowering for learning and curiosity. A simple image or gif wouldn't be nearly as engaging.

It really reminded me of the educational 'toys' that I used while I was attending Montessori school. You could go at your own speed and come to understand a concept by letting you play with all the constituent parts when you felt like it - or if you saw someone else doing it and joined in.

One of the 'toys' I remember from my Montessori experience was these long bead chains. They had all different sizes, e.g. one would be a chain of 8 segments, each containing 8 beads on a rod between the joints. The '8' chain would be blue and have an associated blue cube of beads 8x8x8. I remember the '10' chain and cube was something really to be seen.

We also had really large blocks, because someone dropped one on my head.

"I did the 3D models in @Shapr3D with small post processing in Blender, animations are just done by hand" https://twitter.com/BCiechanowski/status/1387827101294686210...

"Just bare webGL, it’s not that many lines of code to setup and it gives me complete control over what I want to render" https://twitter.com/BCiechanowski/status/1388504529646211076...

> Surely he didn't write this JS by hand

It seems parts of it are auto-generated like all those co-ordinates. But then some parts appear as if they are hand-coded.

I also noticed that other program texts are getting assigned to variables (example "line_vert_src"). Could someone please describe what's going on?

That explosion animation is absolutely mind-blowing. Goes to show what can be achieved if someone focuses their attention to a topic to understand it in depth and explain it at the same depth.

> I also noticed that other program texts are getting assigned to variables (example "line_vert_src"). Could someone please describe what's going on?

These are fragments of code in "OpenGL ES Shading Language", passed to WebGL. See for instance [0] for a tutorial.

[0] https://developer.mozilla.org/en-US/docs/Web/API/WebGL_API/T...

I looked through the code. The model indices may have been generated, but literally everything else looks hand written (albeit probably lots of copy paste).

He doesn't even use any libraries for the 3d math, input, rendering, etc. Pretty inspiring.


> [...] We’ve barely scratched the surface of optics and camera lens

A real genius certainly, but, I'm always doing this; bad choice of metaphor here!

"bad choice of metaphor here! "

Or a funny one.

I like the the interactive visualizations a lot and some of the setup (a camera picture is a thing that changes in certain ways as you fiddle with these 3 parameters, etc). But I always have a hard time telling who the actual audience for this stuff is. If it's someone who has very little exposure to how cameras actually operate, is a Bayer filter really the second thing they need to be aware of? I don't really follow the pedagogical narrative/intent here.

Love how it's written

> While reliable and easy to direct, a cannon ball won’t be very effective at pushing the crank

That was a fantastic metaphor, and though I am intimately familiar with engines I had never thought of the crankshaft as four simple hand cranks stuck together before.

I wonder if it was inspired by well known this classic video explaining differentials.


Great video. I wish there were videos this clear to explain everything!

Yeah, and to think that some people are incredulous when I say that I need animation support in my electronic documents !

This is even better, I will bookmark it as an example.

Saw a startup recently building something like “PowerPoint for animated documents” - https://www.unscene.app/

Crazy that no one’s made this before

Really cool, but : - For the love of God, why a web app ?!? - We pretty much already have what I'm asking for in the form of MHTML, I just need Firefox support !

"This page summarizes pretty good what web technology is capable of, when in the hands of a real professional."

I was looking at this when I went to bed, and though the subject matter isn't completely new to me I was enthralled by the execution and stayed up and read all of it...

Absolutely LOVE the way this has been put together, it really speaks to me of beauty in simplicity, at least from the visual perspective!

>One of those web pages which deserves an award.

Yes. This is what Web Pages should have been. Simple, Clear, with Animation to help with certain demonstration. He could have been add an ad at the bottom if it needs to be. A Web page with added on interactivity.

Instead we got Web Apps.

The award is the bookmark. This is a great reference for cleaniness.

When I was a boy, my dad decided that our '66 Mustang with a straight 4-cylinder engine needed new piston rings. I helped a bit but mostly watched as he tore down the engine to the barest elements, only the engine mounts keeping the block held up in the compartment. The crankshaft, connecting rods, tappers valves, piston heads, piston rods, all laid out neatly on the garage floor along with all the nuts, bolts, washers, seals, gaskets, belts, and everything else you see in this video.

Although I really appreciate the reliability, efficiency, and durability that modern engine design has brought, a part of me is sad that modern cars are all about chips and software, and the average guy in his garage or under a shadetree can no longer break one down to the bare bones of electromechanical parts and put it back together better than it was.

> Although I really appreciate the reliability, efficiency, and durability that modern engine design has brought, a part of me is sad that modern cars are all about chips and software, and the average guy in his garage or under a shadetree can no longer break one down to the bare bones of electromechanical parts and put it back together better than it was.

That's a totally flawed understanding of modern ICE vehicles.

There was an era of vacuum-line misery separating the 70s and 90s, where you'd almost certainly never get it back together and functioning good as new again with the literal miles of vacuum lines and solenoids.

But modern stuff, especially with just 4 cylinders, is relatively simple and entirely DIY servicable. Wiring harnesses have replaced all the vacuum lines, and everything has a physically unique connector pair, and the harness routing is well described in the service manual. So all the guesswork is gone there, honestly the worst part on new stuff is not overlooking any of the grounding lugs.

I share your attitude WRT modern EVs, but I bet if we just treat the controller and battery as black boxes we don't attempt to disassemble and service, the rest is just more of the same simple machinery except with no hazardous gasoline and motor oil to drain and handle.

> "Wiring harnesses have replaced all the vacuum lines"

Of course, now days the wiring harnesses themselves have become huge and unwieldy in many vehicles - literal miles of cables! Automakers are looking at technologies like automotive ethernet and even wireless communication in order to reduce the cost, size and complexity of wiring.

> "I share your attitude WRT modern EVs, but I bet if we just treat the controller and battery as black boxes we don't attempt to disassemble and service"

Some EV batteries are quite serviceable (eg: LEAF), with the pack being able to be disassembled right down to the cell level relatively easily. Although admittedly, some modern pack designs are moving away from this level of serviceability (eg: Tesla, whose cells are cemented in place with fire-retardant foam/glue. Disassembly is a one-way operation).

Things like motor controllers/inverters tend to be very reliable so there is rarely any need to disassemble or service them during the lifetime of the vehicle. If they do fail there's a ready supply of affordable replacement parts, thanks to salvage from crashed vehicles, so it's often easier to just replace a faulty part than attempt to service.

> Of course, now days the wiring harnesses themselves have become huge and unwieldy in many vehicles - literal miles of cables!

Engine harnesses are not that bad in my experience, especially not for a small 4-cyl. Chassis harnesses, with all the bells and whistles they keep piling into smartphones on wheels, agreed. But we're talking about engines here.

> Things like motor controllers/inverters tend to be very reliable so there is rarely any need to disassemble or service them during the lifetime of the vehicle. If they do fail there's a ready supply of affordable replacement parts, thanks to salvage from crashed vehicles, so it's often easier to just replace a faulty part than attempt to service.

I figured as much. This is basically already the case with all the various modules littering the chassis in modern ICE vehicles. We don't service the power steering or engine control modules; it either works or you replace it, usually with some cheap used replacement from a wrecker. Unless the car's been flooded, the miles and age don't seem to be a problem except the occasional cold solder joint.

Many more of my hours have been wasted fussing with jets and floats on old carburetors than any control modules on these newfangled computerized vehicles.

An aspect that appeals to me is interchangeability. If you needed to replace an engine or other major components, even just to similar items in the manufacturers lineup, there's definitely a "golden era" of late 80s to early 2000s cars where that is feasible for the...more enthusiast home mechanic. While not impossible for modern cars, it is far far more difficult.

I think the design of a wiring harness is actually a good analogy for a well-created API, in that it provides a handful of endpoints, each of which fulfills a "contract". On modern wiring harnesses, it's pretty hard to connect the wrong thing, because the connectors are physically "typed", in that the male and female sides are uniquely shaped so only they will mate up, rather than having a generic connector that plugs in to every sensor.

On the contrary, twisting a distributor to set timing, or doing _anything_ on a carburator, will make you long for those aspects of ICE to be abstracted to control by software. Weirdly enough, that's what's happened over time in cars with direct injection controlled by ECUs.

Obviously it's nostalgia for me, but timing lights, distributors, points, carburetor ports and butterfly valves, you could really see into the mechanisms. Hell, my dad (who was a master mechanic and worked on cars and railroad diesel engines to put himself through college) took a drill to the fuel injectors on a shitty 80s Chrysler engine that was knocking and stalling when cold (no amount of adjusting the choke could fix it). I drove that POS in my college years and never had a problem with it.

If you're doing minimally invasive wrenching on stuff that is in good condition electronics are fine until you have to do serious work to them.

Grafting two engine harnesses together because you can't buy the one you need (because nobody sells that stuff for 20+yo vehicles) will make you want a carburetor.

Plus it doesn't help when vechicle manufacturers will not share repair information with the customer, or independant repair shops.

It doesn't help when they refuse to sell scanners to independant shops, or customers.

Yes---vechicles are much more complicated, but every vechicle sold in America should be required to tell customers up front about the ease, and accessibility of required repair information.

My point is if they didn't hide repair information we might not look at modern vechicles as Challenger space ships.

I have been casually looking to buy a new vechicle, and every salesperson laughed when I asked about buying a factory manual.

Sales guy, "Oh--no one works on their car anymore, they bring it here." Sign behind him said, Shop rate is $275 hr. People drinking Starbuck's coffee for free though.

My father told a salesman to throw in a factory service manual on the sale of a '97 Dodge Dakota. Salesman, "Hell yes!". He gave him the manual before he received the truck.

And yes--after dealing with a failed smog check this week, and seeing the PID only shows up on the dealership scanner, I am more than pissed over propiatiary information. Failed smog--$125 gone. A trip to the dealership $450, for a sensor that one of the better scanners didn't have access to.

I went to Automotive School, and worked on all my vechicles ever since.

I am so hesitant on buying a new car.

Today is definitely my Right to Repair Day.

I thought about RTR movement while shopping. I was trying to think about being out, people getting vaccinated, friday, but that Right to Repair was stuck in my mind. We need to all get behind the movement.

(To tired to edit.)

Well spoken, Right to Repair, Right to be Healthy, we keep on dreaming

This page is a work of art.

And going through the archives[0], looks like all the pages are!

It's really, really rare to see this level of care, attention and detail put to something we all consider will be seen only for a few seconds. But as a testament to the adage "the cream rises to the top", I spent around an hour going through the website.

Pure craftsmanship. Thank you.

[0]: https://ciechanow.ski/archives/

I wish entire wikipedia was as informative as this one page.

Would be happy to pay for some commercial encyclopedia of that kind and quality.

When I was a child I absolutely loved Encarta 96. It fit on a single CD and had enough interactive material. With today’s computing, network and disk possibilities I don’t see any reasons why nowadays there is no single curated source of truth about the world around us.

Instead, all the information is spread around the vast amount of resources around World Wide Web and in order to find something meaningful you sometimes have to trudge through hordes of bullshit.

Make no mistake, making articles of that level of quality requires world class skills in software engineering, communication, math, foundational engineering skills (physics/mechanical/…), etc.

The number of people on earth who can author such content is extremely low. The number of people with the vision, fundraising ability, and general meta skills needed to lead a team of people doing such work is likely even lower.

Creating an entire encyclopedia at this level of quality and interactivity would be a Herculean project.

In the meantime, we have other kinds of similar Herculean projects like Khan Academy and Wikipedia, and they’re pretty great too :)

I totally get the herculeanity of the effort. But I also feel there’s vacuum in this space. And I would be happy if our children had access to a high quality source of information.

The quality of the explanations, and progression of complexity, reminded me of an old video that explains how a car's differential (rear end) works:


Skip to 3:30 for the explanatory part.

Wow, this video was fantastic, thanks for sharing. I see how the progression reminded you of this, but the physical demo presents as more of a history-of-mechanisms lesson, which is fascinating.

I also appreciated the humor. They seem to have built a working mockup of a car with the driveshaft penetrating the passenger compartment, just to make the joke that it would be inconvenient to rest luggage on the spinning shaft.

If you really want a rabbit hole, I suggest this guy's channel. https://www.youtube.com/channel/UCwosUnVH6AINmxtqkNJ3Fbg

This video is a gift.

This was really educational! I love the design of the webpage, and I especially like how you can rotate the 3d diagrams and see each component from every angle.

If anyone is looking for a hands on educational model, my 6 year old and I put together a model V8 engine [1] (made by Haynes of technical manual fame I think) that does a pretty reasonable job of capturing the essence of the main parts of an internal combustion engine. It kept him (and me) thoroughly engrossed for a few hours.

[1] https://www.themotorbookstore.com/build-your-own-v8-engine-m...

I had no idea until I read your comment that you could click and drag the engine models! Insane!

The text immediately before the first image says “You can drag it around to see it from other angles”. Our attention spans are deteriorating quickly…

Ditto. Thanks.

Another great Bartosz Ciechanowski creation. Also check out his past work [1] about light & shadows, cameras & lenses, color spaces, floating point, etc.

[1] https://ciechanow.ski/archives

Well done. According to the author's Patreon, this is his first article that's "Paid for by patrons" though no details are given. His Patreon is set up so that donations happen whenever he publishes a new article. I guess the advantage over recurring donations is that it doesn't pressure him to crank out content - he can just do it on his own schedule, and donations are always justified.


I just built an engine for my car. One thing I gained an appreciation for was how CHEAP cars and engines are. There's probably nothing else with as precise machining that is as inexpensive.

Engine cylinders are honed to accuracies that are less than 1 thousandth of an inch. Crank journals as well and rod journals. This is all precise machine work with metal. I use inches here because in machine work thousandths of inches is the language du jour. Transmissions are similar works of very precise and clean machine work.

The distance between a crank bearing or rod bearing is less than 2 thousandths on modern engines. A small amount of oil in that tiny space is all that keeps your engine from having metal on metal seizure.

So one would think that when EVs reach the same scale they will be significantly cheaper than ICE vehicles.

The raw materials may continue to cost more for EVs. Motor windings are generally copper, and batteries contain lithium and (usually) cobalt and nickel. Permanent magnet motors sometimes contain rare earths.

One could make an EV with aluminum motor windings and electrical cabling, no rare earth magnets, and lithium iron phosphate batteries. That would keep expensive materials to a minimum.

EVs don't need a catalytic converter, so that's a big thing in their favor.

I'm looking forward to mass manufacturing continuing to bring down EV component prices. I think we're a long ways from the point where material costs are the bulk of the expense.

> EVs don't need a catalytic converter, so that's a big thing in their favor.

I feel there is some sort of scam going on with catalytic converters for the last few years. I actually worked in a small family owned auto shop in the early 2000's. If a car came in with a clogged cat, we'd first fix the source of the issue (usually a mis-firing cylinder allowing raw fuel into the exhaust) and then we'd cut out the cat, and weld in a universal fit one that we'd get from the auto store for $20. Then charge the customer $200-$400 for labor. I still see universal fit ones[0] although they are $80 now. But still, if you aren't dumping raw fuel or oil into your exhaust, cats are basically good for 300k+ "normal" driving miles. I assume they are expensive now because they are all mostly specially made/custom fit since all car manufactures keep cramming bigger and bigger engines into smaller and smaller spaces.

And while I'm ranting, there's always a negative for every positive and no doubt for the catalytic converter. For a catalytic converter to convert "greenhouse gases", the engine has to be burning fuel at a perfect air:fuel ratio of 14.7:1. While cruising down the highway, an engine could easily save fuel by running a more lean mixture, but this would cause more "greenhouse gases" to go out. So choose your poison I suppose.

[0] https://imgur.com/a/7X0sPlk

I don't think cats are to address greenhouse gasses; they're focused more on reducing pollutants that affect local air quality and human health.

The main greenhouse gas from a car is carbon dioxide. The amount you create is directly proportional to the amount of fuel you burn.

I don't know why modern cats are expensive; it might have to do with the price of platinum, palladium, and so on, and the relative amount of those materials. A cheap generic cat might have the bare minimum amount of catalyst, and might not do a very good job.

> I don't think cats are to address greenhouse gasses; they're focused more on reducing pollutants that affect local air quality and human health.

I thought the same thing, but interestingly that's only kinda true. If anything, cats increase CO_2 as a desired end goal, because it's better to have CO_2 than CO or NO_x (or so the EPA has decided, I am no where near qualified to decide that). The issue with running too lean is that the reactions in the cat would rather use plain O_2 than NO_x, and so if you have too much O_2 (lean) you won't get rid of any of the NO_x [0]. Before looking into this I thought lean engines produced more NO_x because of higher cylinder temps or something like that (which might be true as well).

Cats not reducing NO_x when lean is essentially why Volkswagen (and practically every other manufacturer has been caught doing similar things to diesel engines) was cheating the test. Diesels have no throttle so they are (almost) always lean, typically very lean.

This does make me wonder, though, does running lean actually increase fuel efficiency? Obviously rich lowers fuel economy because not all the fuel burns, but assuming it all burns what does it matter if you have 1 gram of fuel to 15 grams of air in the cylinder, or 1 gram of fuel to 18 grams of air in the cylinder? You'll still get the same amount of energy, right?

[0] https://en.wikipedia.org/wiki/Catalytic_converter#Three-way

Diesels with combined SCR-EGR can go below US limits rather easily.

> A cheap generic cat might have the bare minimum amount of catalyst, and might not do a very good job

It depends on the car/engine. My old Mazda RX-8 had a huge cat - longer than the muffler and cost me $2,000 to replace (including labor) back in the late 2000's.

The rotary engine in that vehicle had a terribly difficult time passing California's emission laws even when it was brand new off the lot - which led to strange "hacks" including a blower motor that moved high volumes of air through the exhaust to heat the cat sooner and somehow improve it's numbers, among other things. I assume the extra-long cat was part of the shenanigans Mazda had to go through to get it compliant.

> moved high volumes of air through the exhaust to heat the cat sooner and somehow improve it's numbers

This is because the catalyst works more efficiently at higher temperatures. Emission regs also test vehicles under a cold start. The quicker the cat can be heated up, the quicker it starts working, and that equals fewer total emissions over a given period of operation.

It's funny you mention the RX-8, since I'm in the (slow) process of converting one to electric. That weird cat blower was one of the many parts I removed while thinking "I'm glad I don't have to understand or care about why this car needed something like that in the first place".

Just talking about the RX-8 brings back great memories - what a strange, yet beautiful car!

The cat blower, and the subtle whining sound it made when you started up cold was one of the ways every RX-8 owner was hazed into the fold... after calling the dealer or posting on a forum and finding out it's entirely normal!

Other oddities included how it deliberately burned oil (scaring new owners into thinking they had a serious engine problem), and how you were required to drive it hard to clear out its engine ports (multiple Mazda mechanics confirmed this factoid) - driving it like a normal car would literally clog up the exhaust ports and cause a loss of power (something to do with the lack of moving valves). If memory serves right, it had only 3 (!!!) moving parts in the engine, and was perfectly content to hang out at 9,000 RPM all day - that's incredible.

But, it seems the issues Mazda had maintaining it's emission certifications, and warranty issues with those apex seals (mine had 3 engine replacements over it's lifetime) eventually caused it to be retired. I was sad back then, and still sad we don't have a new improved version - there's really nothing else quite like it out there, not even the RX-7. It really was/is an enthusiast's car.

Good luck on your project - sounds like a fun one!

I'm hoping LiquidPiston's rotary engine design pans out: https://news.ycombinator.com/item?id=25450477

In theory, it should fix some of the maintenance issues (apex seals are attached to a stationary part of the engine where they can be more easily lubricated) and fuel efficiency / emissions issues (combustion chamber is closer to spherical).

I like the idea of the Mazda rotary engine, but I'm not really surprised they stopped making them, due to fuel economy and emissions. And at them moment, the hundred-thousand mile engine rebuild interval basically means you can get an RX-8 with a bad engine for almost nothing, which opens up a nice opportunity for EV conversion. It's hard to imagine a nicer platform to start from.

Wow, that LiquidPiston rotary looks very interesting! I hadn't seen that before - I too hope it pans out.

> I'm not really surprised they stopped making them, due to fuel economy...

Eh, nobody bought that car for the fuel economy!

The car sold itself... just one test drive and you had to have it. I've owned and driven muscle and other sports cars, and still nothing compares to the RX-8 - it's just such a unique experience.

Not sure how you're doing the conversion, but if you're keeping the carbon fiber driveshaft (vs. a motor on each wheel I suppose), there will be nothing keeping it from screaming off the line with an electric motor under the hood (traditionally the wankel wasn't good off the line with low RPM's, power band kicking in around 6500 if I recall - could make for a great "sleeper"). Although I'm unsure if the driveshaft would stand up to the torque a motor would output, since the wankel wasn't particularly torquey.

If you're not already, keep a blog and pictures of the conversion - that would make for an interesting read!

> Eh, nobody bought that car for the fuel economy!

True enough, but I'm sure there are other factors in play, such as public policy. Fuel economy standards have been going up.

The motor I'm putting in my conversion is a Netgain Hyper9 (high-voltage, double-ended shaft version). It's about 120 horsepower and less than 200 foot pounds of torque, so in theory the clutch/transmission/driveshaft should be fine. (I'm keeping the 6-speed transmission.) It probably won't be particularly fast, but we'll see. More powerful AC motors exist, but they tend to be expensive.

I haven't posted any pictures yet; I've been meaning to, just haven't gotten around to it. There's another guy in the UK I think with a youtube channel that's doing close to the same thing, but with a Leaf motor.

On the other hand the quality and performance of those $80 catalytic converters are questionable at best. They have neither the longevity, nor the performance of the original part. They might last even 10 times less, and they're usually just barely good enough to pass the emissions tests, which is already the lowest bar to pass given how all manufacturers optimize for that. Real life emissions are far worse.

And the purpose of the catalytic converter is to make sure the CO, NOx, and unburned fuel are rapidly oxidized to CO2, N, and water before leaving the exhaust system. The outcome is that you will produce more greenhouse gases but fewer compounds that are more immediately dangerous to people, especially in cities. So it reduces localized pollution at the price of more CO2.

Catalytic converters don't reduce greenhouse gases. Their function is to reduce poisonous gases: NO, NO2, O3, CO, HO2, and sometimes HCN and H2CO. The good news is that all of these compounds are thermodynamically unstable so a catalyst can destroy them.

I don't know where you got the 14.7:1 number but I am certain that NOx are unstable at any concentration (at or near STP) and will always be depleted by a catalyst.

Another commenter is unsure whether the NOx or some GHGs should be reduced preferentially. To clarify: CO2 can't be removed, it is stable; only CH4, N2O and O3 can be removed, and they are not present at relevant levels (except ozone which is poisonous) anyway. The poisonous gases are far more important — NOx pollution alone kills thousands of people every year (statistically, considering excess deaths as correlated to air pollution).

The increased price of catalytic converters is partially related to the supply of palladium, which experienced a glut following the collapse of the USSR. The Soviet palladium ran out in 2012:


>I don't know where you got the 14.7:1 number

The cat has to be hot to catalyze. The engine is run rich so unburnt fuel makes it to the cat and is combusted there, warming it up enough to also kill the undesirable gases. This is wasted heat... unless you mount a turbocharger after the cat, which has its own set of weird tradeoffs. (I've never heard of a factory car with a rear turbo)

Tesla already uses aluminum for power cabling because it’s cheap and lighter weight. Tesla Model S were induction motors (at first at least) with no rare earths, and Tesla is partnering with CATL for lithium iron phosphate batteries in lower cost versions of, if I believe, Model 3 and Y.

I thought CATL makes lithium iron phosphate batteries, and lithium sulfur hasn't been commercialized yet. Unless there's some news on that front I missed?

I think induction motors tend to be less efficient than permanent magnet motors (and thus require more cooling). The Netgain Hyper9 (a popular motor for conversions) is a permanent magnet motor which doesn't use rare earths. It's very efficient but not particularly powerful (though that may be due more to the relatively low voltage it runs at).

That's cool that Tesla is using aluminum for power cables. Makes sense to save cost and weight where you can.

Yes, I meant iron phosphate. (I’ve had sulfur on my mind from Bye Aerospace’s 925km range 8-seat electric aircraft, working with Oxis Energy.)

Note to replace copper wiring with aluminum, you have to go up at least one gauge size.

Or raise the voltage at the same time you change from Cu to Al.

Yeah, aluminum is a worse conductor so you need thicker cable. It's less dense, though, so I think it usually comes out as being lighter. Thicker cables can be more inconvenient. I think aluminum also tends to have more problems with oxidation causing too much resistance at electrical contacts.

I think for motors generally you just end up with a larger motor for the same amount of power.

All points you make are very true. In addition, aluminum tends to crack as it ages and you'll find aluminum wiring is usually a culprit in electrical fires. In the world of mobile electronics, it's usually looked down upon as the cheapest alternative when compared to real copper conductor used in higher quality automotive wiring.

It only requires proper engineering of the connection. Aluminum itself doesn’t crack in properly engineered joints. What fails in old houses is shoddy connections.

If people look down upon it, it’s because they’re either lazy or ambivalent. It’s the superior performance solution in some situations.

"Tesla already uses aluminum for power cabling because it’s cheap and lighter weight."

Ugh, really ? That offends my sensibilities ...

Why? A properly engineered aluminum power cable is superior to a copper one when weight is at a premium.

Aluminum is less ductile and prone to galvanic corrosion. It can definitely be engineered to work properly, but copper is much more forgiving.

cmon man. the total weight of pricey metals in a car is so low, there is no way its going to offset the cost of precision machining. tolerances < 1 thou and callouts for surface finish and perpendicularity are expensive!

Hard to say. Those tolerances would be expensive in general purpose machine work, but in engines those tolerances have been in place since at least the 1930s, and so economies of scale bring those costs down (ie, using specialized machines that are really good at boring precision holes and measuring them. The costs of those machines get amortized over every engine).

I'm sure a motor is cheaper than an engine (less steps to make), but they still require precision manufacturing, and all the other parts aside from the motor (driveshaft, axles, brakes, etc.) are more or less the same.

Plus, the cost of those other materials is going to increase if demand for EVs goes up.

evs could drive lithium but i really doubt they would influence copper that much, since it is used so much already

I think the more constraining commodities are things like rare earths[0] and other important metals like cobalt.

[0]: I know they aren't that rare, but they aren't mined/processed in many places and it takes a long time to bring a new mine online.

Somehow car manufacturers are able to make engines, transmissions, transaxles, and differentials really cheaply, so apparently all that precision manufacturing doesn't really cost all that much when producing at high volume. This should be equally true of EVs and combustion-engine cars.

Raw material costs might still be less than the manufacturing costs, but they're pretty hard to avoid. Also, materials that are cheap now might not be if demand grows faster than supply.

> One thing I gained an appreciation for was how CHEAP cars and engines are. There's probably nothing else with as precise machining that is as inexpensive.

Not to denigrate the amount of engineering that went into car engines, but literally, what about chips? Devices that contain billions of transistors, arranged precisely on the order of nanometers. Yet they cost only hundreds of dollars.

They're apples and oranges. Chips are not machined, they're etched in batches. Their "tolerances", so to speak, are limited by the wavelengths of visible or UV light they use for creating the masks and exposing the photoresist that protects the wafer from hydrofluoric acid and other etchants. There's no mechanical force involved, except to spin wafers to apply coatings and move them between each stage of the process.

Engine blocks, on the other hand, are CNC machined one at a time and the force of machining steel causes vibrations that move the cutting tools thousands of nanometers back and forth. Placing both in the same building, for example, would likely cripple the semiconductor fab. Having a machine shop in China make a one off would likely cost as much as a luxury car.

Yes you are referring to another insanely complex thing that is very cheap relative to making one of cost due to mass production. But it isn't machined metal :) I didn't say I don't appreciate electronics too.

> "I use inches here because in machine work thousandths of inches is the language du jour."

Yeah not in Australia unless your machinist is >50 years old. Metric is more accurate/easier/less prone to mistakes. Metric is what we use.

Still widely used and taught in the machine shops of highly reputable universities over here in the U.S.

If you're under 40 and can't use metric and imperial jargon without a second thought in the shop here that's a different problem. I personally enjoy doing machine shop-esque metal fabrication in metric and woodshop type things in imperial, but all machine shop instructors I've met through several good stem uni's that look even slightly middle aged love to talk in thou of inch, some to the point of getting quite physically frustrated when asked where the metric drill index/reamer set are in otherwise highly stocked shops...

Also, I've noticed and heard the same from others in surrounding states - Fluid Dynamics professors love to include absolutely unecessary boatloads of strange units and conversions in coursework/exams to apparently "prepare us for the shitshow that is industry"

I'm not denying the metric system. Just in the USA it is thou period. and if the measurement is a consistent unit of whatever it works. Also GM (and Holden in oz) are inch based. So using metric will subject you to mistakes possibly. I agree though in science SI is the way to go

Yeah I cut my teeth on Subaru engines (helped having a gf who was a subi then telsa mechanic walking me through it). Subi are all metric tho. My workshop is a mix of metric for new gear and imperial from my old mans days running a farm.

We even have some stuff thats neither metric or US imperial, but is british witworth imperial...so different again and just enough to make a difference. Makes for some confusing repairs when your working with stuff that's had a mix of all 3 systems due to a long life of repairs.

I'm in Europe, and I've had/worked on German, Japanese and Swedish cars and boat engines. Metric all the way.

Only time I've needed an imperial set of tools was when overhauling a B&S lawnmower engine.

I was trained in Australia, in the past decade, and was taught thoroughly in both metric and imperial. The engineers and machinists I have worked with that insist metric is the only way habe been more prone to mistakes when imperial components pop up, as they do. Accuracy is down to the spec, the person and the machine, ease of use is identical when decimal inches are used, mistakes are a result of poor communication.

I just built an engine for my car. One thing I gained an appreciation for was how CHEAP cars and engines are. There's probably nothing else with as precise machining that is as inexpensive.

When cars started getting electronic engine controls, there was much internal grumbling about the cost. One Ford production guy, on hearing that the engine controller cost about $100, said "I can make the whole engine for 100 bucks."

Anyone who has the inclination to build an engine, should.

It is super rewarding not to mention you get to buy a bunch of really cool tools.

I build a 350 Windsor from the block. The research and design decisions were one of the best parts of the project. Then to put it all together and realize the power was amazing.

Ford (Aus) 4.0 was a great first build for me. I'm now taking my time on a Toyota 4K 1300cc, learning a lot more, and taking the time to design new components for it. Can't recommend it highly enough, though not for everyone to be sure.

Not only the tight measurements, but I've always been amazed at the precise timing of all the little moving parts, the valves all opening and closing at precise to-the-millisecond times so that each stroke happens, at 6000 RPM! So impressive. Especially with an interference engine, where getting that timing wrong means bent valves.

Mmm.. not really. It's just a cam and a spring. Pretty easy to get that bit working by yourself. Variable valve timing and lift is much more impressive.

I think automatic transmissions are more impressive looking than engines when they're open. They resemble EV motors too!

Automatic transmissions also have hydraulic logic gates in the valve body (implemented with check-balls and piston servos), even if they're also electronically controlled. Drag-racers will reprogram the valve body to change the shift order, have launch control, etc.

VW group has a dual-clutch automatic transmission that includes an EV motor for their plug-in hybrids, the DQ400E. It looks pretty cool indeed!

> I use inches here because in machine work thousandths of inches is the language du jour.

Only in the USA ;)

The rest of the world figured that using prefixes with a predefined universal multiplier is more practical.

Therefore you can use the milifoot equal to a thousandth of a foot, or the kiloinch equal to one thousand inches, or the microyard equal to one millionth of a yard, maybe even the centifurlong equal to one hundredth of a furlong.

We are quiet proud of our prefixes. Now if only we would decide on a single reference unit to which to apply the prefixes. Conversion from megainch to hectofurlong is rather inconvenient.

Nice! What engine did you build?

>The distance between a crank bearing or rod bearing is less than 2 thousandths on modern engines. A small amount of oil in that tiny space is all that keeps your engine from having metal on metal seizure.

The BMW S65 and S85 engines are prime examples of what happens when the wrong tolerances are chosen. I can't think of another engine family where rod bearings are considered a maintenance item.

I built an LSX (Aftermarket GM) iron block engine (V8 LS) for a CTS V. I had to get some very precise tools (Have to measure to 10,000ths) or they were useless for bearing clearances and verifying cylinder diameters. My cylinders were 4.155 bore, and the bearing clearances were around 1.8 thousandths. Forged pistons, rods and crank.

I had cracked a cylinder/piston on the original LSA. I did not trust anyone to do the work so I did a lot of research and did it all myself. I appreciate someone asking because my friends and software dev co workers aren't interested :)

Yes you are right as far as LS engine builders there's loads. I could have ordered a crate engine from Texas Speed and been done with it. And yes for hours of my time spent vs hours of money saved I lost a ton of money. But all it takes is one very small mistake to make an engine short lived with these exacting tolerances. I'd rather blame myself than deal with someone kicking the blame back. It was also a personal satisfaction thing.

My wife's engine had an issue and it was the middle of winter so I said whatever let's just have a shop fix it. In the process they "flushed the transmission" and it failed 4 days after we got the car back. Of course they stonewalled us and I can't prove they broke it. So I ordered a late model wreck transmission and replaced it and 3 years later still running strong.

But I then decided that I would never be in that position again where someone could tell me it wasn't their problem and get me aggravated. With this engine I built it from raw parts. I had the block machined, and I had the tools to verify.

It was certainly not worth my time, but as you said I love working on cars too.

I have a buddy that is adamant about not flushing transmissions if you dont have a issue because he think its guaranteed to have an issue after, from his experience. lol

There is some truth to that, but not never. A flush will dislodge any metal shavings and crud from the moving parts. The filter should catch these, but the filters themselves can get clogged, and then bye-bye transmission.

Flushing can really be bad if you've never done a routine flush on a schedule. You don't want to go 150,000 miles before your first one. You would need a garage with a forced flush system to move it all out, and then probably flush again soon after to make sure all the gunk is out.

Transmission oil breaks down with heat and wear like any other, and will eventually contain sludge and dirt.

I'd concur with that. Note this was one of the notorious to fail JATCO nissan/mitsubishi transmissions. Blowing fluid through with pressure makes no sense. Sediment sitting in pans does not affect operation until it is agitated into suspension

The Nissan automatics and especially manuals(cd009) are fairly strong. It's their CVT that's the issues. I don't know why Nissan insist on using them with their V6's.

>I had cracked a cylinder/piston on the original LSA. I did not trust anyone to do the work so I did a lot of research and did it all myself

I love working on cars so I totally get wanting to do that, but why didn't you trust someone else to do the work? There are probably more reputable LS builders across the US than any other engine family.

It sounds like he wanted some very precise work done. Quality in the blue collar trades has gone to nil in the last decade. And if you do find someone that is very detailed and "by the book" level of quality, you are going to pay 3X the normal labor rate. For instance, this is a performance transmission shop [0] that regularly takes apart "precision" rebuilt transmissions only to find they were not done right at all.

[0] https://youtu.be/aI5iO2YSHMs

LS engines are among the most common engines in custom built cars, and there are countless shops out there who specialize in them. No offense to him or you, but it's quite ridiculous to believe you can do a better job building an engine on your first try than shops like Texas Speed who have been doing it for decades with full blown R&D labs and regularly build 2000+ horsepower motors, all with highly skilled machinists and engineers using professional equipment that the average person would never be able to afford.

Edit - For reference here's a video of the shop I'm referring to. They're far from a podunk operation. https://www.youtube.com/watch?v=8HgwF5dISmU

I could do a better job than them in all due respect. I care about my job more than anyone on earth. I know they do good work but if we could both measure to the same specs and know we did it right, how could I do it worse than them. we have the same measuring tools. Not that I think they do bad work. But if you ever built an engine you know its all about attention to detail. there is nothing they have to verify the integrity of the build that I don't to a similar level of precision.

Edit: I dont have the machines they do, but when my bare block comes back from the machine shop, my tools are just as good as theirs to verify the dimensions are correct. That isn't possible to verify with a built short or long block. They could possibly have 100 employees that care as much about my job as me who knows. This is a job about verification of specs and assembling correctly not of insane tech. They don't have anything I dont when assembling an engine. Machine work yes

Texas Speed or TKM are two places I’d use if I were doing an LS build.

It helps that they are abundant (in the hundreds of millions units produced), have been in use for decades (since the mid-50s), and are simple to work on (as evidence by the OP randomly learning to machine one).

As cool as 2-atom thick plasma transfer wire arc cylinder liners are, that's not something which will ever be available to a layman.

I really doubt the OP did the machine work himself, those tools are not affordable for just using once or twice. Buying bore gages and mics however is totally doable.

And no, the LS motors have been in use since '97. Including the gen1/2 small blocks doesn't count, there are no shared parts between them.

17-18 thou here on my LS6 on the rods. 23-24 on the mains. I'd like to see tighter on the mains, but not sure if its worth ordering another set of bearings and using 1/2 of them to tighten up 1/2 a thou like i did on the rods.

what amazes me is the cam lifts we're running these days. I'm running .646"/.649". In the 90s .500" was big for a street motor, and only full blown race motors were running whats normal now.

Damn, dropping a new engine in a CTS V? What year? NA? How much power are you shooting for? The CTS V is definitely one of my favorite cars, I'd love to own one one day, but the ones with the manual trans hold their value pretty well :)

It was and still will be supercharged. It was 650 crank Hp, and will be over 800 conservatively . and its manual ;)

Yep. Jealous. Best of luck on the build!

Very cool. Although I own an LS, I've never touched an LS. The Sloppy Mechanics guy is impressive though.

Since a short block is mostly just a short block, I'll be interested in seeing if LS heads/intake manifold/headers takes off in the SBC community.

Huh? What do you mean "takes off". Do you mean do we build LS motors now instead of gen1/2 SBCs then yes.

If you mean "do the LSx heads drop onto a gen1/2 SBC", then no, not at all. only thing common between them is the cylinder spacing. The LS uses 4 bolts per cylinder like a ford, instead of 5 like the SBC, the firing order is different, the valve layout is different (ports are symmetric vs mirrored), etc.

Firing order is something of an arbitrary thing, it's been done on SBC for some time.

There are small block Chevrolet blocks that accept LS heads (Bill Mitchell maybe?)

(note: I wasn't referring to box-stock LS heads on a box-stock SBC)

Mostly what i've seen is making the SBC take a symmetrical head. Saw some INSANE CFE pro stock heads at the machinist last year, he was building them in a large bore, short stroke deal setup for bonneville to run like 11krpm.

Why did you go iron block for your build? Is it that your were afraid you cracked the block again? How did you do that in the first place. Are you running any boost on this engine?

I'm running 14 lbs boost yes. And yes it was piece of mind that it's much harder to crack and unlike the aluminum block I can bore it more than 5-10 thou if it needed it again. Downside is 100lbs more but this is in a 4200lb car so whatever

Any race or high power engine, especially those that rev quite high will need rebuild - not just in bottom end but often with piston rings and valves as well.

You don't really hear about those other engines much because their buyers understand that a race engine needs more maintenance than any other road car.

Also, not beating on the engine until oil has warmed up to temp will elongate the bearing lifespan quite a bit. I have a friend with E60 6mt S85 that has factory bearings at 110k mi and has perfect oil analysis results.

The S65 and S85 are road car engines, not racecar engines. They're also hardly BMW's highest performing motors. Even Dinan built engines don't suffer from that problem.

They're meant to be dual duty. There aren't any road car engines I'm aware of that use individual throttle bodies or 12+ compression without direct injection.

The S54 engine which came before the S65/85, was also high revving, had 11.5:1 compression ratio and didn't have any of the rod bearing issues. The 20v Toyota 4AGE also had them too with a high compression ratio.

The S54 absolutely had rod bearing issues. There was a recall on the 2001-2003.5 M3s to replace them and BMW switched to 60w oil as part of the remediation. They’re still having issues to this day.

The S54 is also notorious for VANOS issues and cam drive failures. I had to replace the solenoid pack on mine but elected to not upgrade the drive while I was in there.

S54 most definitely had rod bearing issues.

4AGE is 4cyl 11:1 compression producing 155hp with 7200rpm redline.

S85 is 10cyl 12:1 compression producing 500hp with 8250rpm redline.

> Also, not beating on the engine until oil has warmed up to temp will elongate the bearing lifespan quite a bit.

I am curious if there is proof to this. I've always felt the same way. I know in the "old days" with iron pistons, if you you simply started up a cold motor and and drove it hard without a warm up period, the pistons would expand quicker than the block and would start to scour the walls and/or lock up.

But other than that, the only other "proof" I have is from people in high school that like clock work at 3:30 everyday, would smoke tires leaving the parking lot everyday. They seemed to go through motors every 6 months. I'm talking knocking bearings and lifters cracked in half. I've never gotten rough with anything I own until after a 20 minute "warm up" and all has been well (so far).

It wasn't so much locking up or anything but cast vs. forged.

Subaru EJ motors munch through rod bearings quite happily.

What are the indicators that replacing them is neigh?

In my experience with these, when I've heard the first indicator to do it, the damage is done. Standard regular maintenance hasn't identified the issue in advance. I'd be curious to see whether long term monitoring of particulates in oil can make an help though.

I thought once you replaced the crappy OEM bearings you were all set on these engines. I guess it is not the case?

> I use inches here because in machine work thousandths of inches is the language du jour.

I'll make a wild guess: In the USA.

EDIT: Heh, sorry... See https://news.ycombinator.com/item?id=26991690 . This time I really thought I'd checked, but there was lots of catalyst talk in between.

If people were willing to pay the higher cost for the same feature set, why would they well them for cheaper? Why not pocket the extra profit?

I don't like this line of thinking but I'm sure it's going to or already is happening.


Because the whole nature of market competition? People will still choose the cheaper option if its available.

I’m starting to think it may just be minimizing cost. Theoretically that just means “maximize profit”, but I suspect in practice it means a whole slew of bad behavior and design choices. I.e. Pay for the part that’s .0001 cent cheaper than another option, despite the cheaper part possibly being a fire hazard.

competition, a bedrock element of fair markets, capitalism, and efficient economic allocation, something we seem to have collectively lost sight of.

How about your phone.

I've always felt cars were like computers; most people (me included) pay a premium for something mediocre because they don't want to bother understanding it.

My personal solution is to live near the metro and bike as much as possible.

Mediocre in what way? Buy almost any new car from a well known brand today and it will run for 200,000+ miles. You almost need to deliberately buy a mediocre car. Biking and taking the metro is better for the environment, your health, and your budget though. If you are fortunate enough to have that option.

>So one would think that when EVs reach the same scale they will be significantly cheaper than ICE vehicles.

I expect that batteries are the only hangup, there's probably not that much magic left in an electric motor. Additional cost for regen brakes of course.

I agree on the amazing cheapness of it all if you stick with the common stuff. That, along with the low cost of flat panel TVs is a miracle of the modern age.

> Additional cost for regen brakes of course.

Regen braking has no physical cost associated - it's pure software/firmware. The exact same hardware that is used to power the car forwards can be used for regen braking. It can be as simple as a single negative sign in the code to cause the phase to be 180 degrees out, current to flow backwards, torque to go the other way, and the battery to be charged instead of discharged.

One day regen braking will take over hydraulic brakes, and another big cost/complexity of a car will be eliminated. The only reason that doesn't happen today is there are lots of laws and regulations requiring hydraulic brakes, and braking systems typically require more redundancy than power systems.

> Regen braking has no physical cost associated - it's pure software/firmware.

I think this is a slight exaggeration.

The way I understand regenerative braking is that you (effectively) run your AC generator in reverse of what you would in order to accelerate in the direction of motion and then take the current generated by that, rectify it to DC, and use that current to charge a battery. The energy in the system is provided by the back EMF induced in the stator by the magnetic field generated by the motor rotor. I agree that the AC generator is going to stay the same, but I think there's specialized hardware needed for the rectification and charging cycles. At the minimum, you need a more specialized battery and battery management system to make sure that you're balancing the charge across the cells in your battery.

I think you are overestimating unique requirements of typical car engines. They are usually DC powered AC engines, where the DC->AC converter (generating 3-phase AC of controlled power and frequency) can probably run backwards (AC->DC) with at most a few minimal hardware changes, if any.

If you're not overdoing regen, you probably don't need additional balancing. Even if you wanted to charge the EV by towing, you could probably use the normal charge balancing circuitry, again minimal if any HW changes. Non-wimpy batteries and cells should be fine - if they can fast-charge, they can take regen. Might have some limitations on acceptable power vs. temperature, charge state etc.

> One day regen braking will take over hydraulic brakes, and another big cost/complexity of a car will be eliminated.

I have read somewhere that the regenerative braking is much less effective when the car is going really slow, so you still need the hydraulic brakes to come to a complete stop.

True, but you can also use a tiny bit of battery power to do "reverse acceleration" to do the final stopping.

It is true that electric braking would continuously use a small amount of power to stay stopped on a slope. That wouldn't be an issue for a few hours, but you couldn't park on a hill for months without ending up with a flat battery, and then eventually the car rolling away.

Small locking pins are the answer to this, rather like the "park" on automatic gearboxes. They are very cheap, since they don't need to do any actual stopping, but merely keeping something stopped.

Is that right? I didn't know that. I'd like to see a BOM on a regen braking as compared to a simple disk brake system.

One implication to software-only brakes is that it requires that that corner is a drive wheel. If that's the case, I suppose that anti-lock is simply firmware and a sensor.

note: I do see that Teslas have master cylinders, so they apparently are hydraulic braking systems.

A bill of materials? As OP said, there is literally nothing required aside from what is required to make the car go forward. An electric motor is a generator.

Teslas have traditional braking systems in addition to the regen braking. The hydraulic brakes have nothing to do with the regen system.

I appreciate that now. Thank you to everyone for the education.

>The hydraulic brakes have nothing to do with the regen system.

I strongly suspect that they interact for antilock.

I wonder how Teslas deal with parking brakes, historically kind of an issue with disks.

It does seem to me that an entirely regenerative braking system would imply additional expense in terms of the strength of the half shafts, u-joints, transmission if any.

Parking brakes for disc brakes are usually in the center of the disc rotor (like a mini drum) with shoes. Some others like Chryslers have implemented hybrid brake cylinders

> the low cost of flat panel TVs is a miracle

That's really astounding, I just looked at a 55 inch brand name 4k TV going for 400 bucks retail.

Guess it's the same logic as cramming more CPU, etc. into the usual couple hundred sq. mm chip. But you get more CPU for the same money and chip size, which is not as spectacular as more screen size for less money ...

> there's probably not that much magic left in an electric motor.

I believe this sentence has been said about many technologies in the past that definitely invalidated it. I'm more playing devil's advocate than trying to falsify you, likely for being burned sometimes reading or, worse, stating it, haha.

There isn't much more efficiency to be gained in the electric motor world. Motors typically get 90% of theoretical efficiency, so any improvements there will be modest.

Substantial improvements in other metrics might be had, but they probably won't massively impact EV's (weight and costs of the motor are both a small part of the total for a car)

> I expect that batteries are the only hangup,

Batteries are a huge hangup. For example, we don't know how to recycle them and they aren't good for dumps. And, used car batteries are expensive to replace and you get a lot fewer miles per charge out of older cars. Manufacturing of cars isn't great for the environment so we should want older cars to last. This model helps push people to more new cars faster.

No problemo. Just go to a big honkin' flywheel somewhere under the back seat.

there have been flywheel (only) powered vehicles made. https://en.wikipedia.org/wiki/Gyrobus

In a few decades the internal combustion engine will be to transportation what the typewriter is to typing today. It’s kind of mind boggling, but there is really no alternative if we want to stop increasing the CO2 concentration in our atmosphere.

Hmm... Hard to beat that energy density when the workload is large.

Trucks, tractors, planes, ships. Sure consumer cars will be EV but ICEs are not going anywhere

This sparked my curiosity...

Currently gasoline has about 50x more energy per unit weight than a tesla battery pack.

Battery energy densities have tripled in the past 10 years. Keeping on that pace, it would take over 30 years for batteries to be competitive with gas.

When you account for the astoundingly bad efficiency of ICE, though, the gap in usable energy decreases. This is why a tesla can go 300+ miles with a battery that can only store the same energy as 2.4 gallons of gas.

You're likely to hit a hard limit to what battery energy density can reach. The next step will be fuel cells which don't have the efficiency limits of traditional internal combustion.

The Tesla can go 300 miles by making it light, aerodynamic, brakes that recharge the battery, not turning on the heater, etc. Yes, it's a significant engineering accomplishment, but in the heavy long haul world when analyzing break-even points what matters is range improvements due to an increasing energy/weight ratio, not range improvements due to reducing air resistance and inertia. This is because the form factors of the boxcar are basically set by shipping container needs and the weight is going to be determined by the load you are carrying. Munro is advocating for hydrogen powered trucks and planes as hydrogen has similar power/weight characteristics to gas -- electrification of these is going to be a challenge.

> by making it light

If there's one thing that EVs are not, is "light". Model S ranges from 4,561 to 4,941 lbs. A model 3, 3,648 to 4,250 lbs. A Nissan Leaf - 3,538 to 3,946 lbs.

In comparison, a Honda Civic weights 2,771 to 3,012 lbs.

Regenerative breaking is nice but it's very dependent on the particular drive and terrain. Heaters are power hungry as there is very little waste heat that can be used (again, due to the high efficiency), unless they are heat pumps.

The main reason they can go so far with so little energy is the efficiency of electric motors.

> as hydrogen has similar power/weight characteristics to gas

No it doesn't! It has horrible energy density per volume, compared to any gas or liquid fuels. You can improve this by using high pressures (energy loss) or cryogenics (even more energy loss). But it's pretty bad to begin with. Turns out that the best way to store hydrogen is by adding some carbon atoms to it.

> If there's one thing that EVs are not, is "light". sigh

Obviously we are not comparing about the weight of an EV compared to an apple or vehicle that doesn't require a battery. We are talking about extreme measures taken to make the car lighter so it can improve range. Replacing cheaper steel with more expensive aluminum, reducing even surface area of plastics, reducing wires. Truly amazing steps were taken to reduce weight.

> No it doesn't! It has horrible energy density per volume,

volume? Seriously? "The energy in 2.2 pounds (1 kilogram) of hydrogen gas is about the same as the energy in 1 gallon (6.2 pounds, 2.8 kilograms) of gasoline." https://afdc.energy.gov/fuels/hydrogen_basics.html

You're comparing mass to volume in that last paragraph there. Based on a quick google search, that 1 kilogram of hydrogen is going to take up 3.4 gallons as a cryogenic liquid—so even more as a compressed gas.

Source: http://www.uigi.com/h2_conv.html

> Obviously we are not comparing about the weight of an EV compared to an apple or vehicle that doesn't require a battery.

Well, yeah that was my original intention. Teslas get comparable range to ICE vehicles while using less than 3 gallons of gas. That comparison to ICE vehicles demonstrates the efficiency of electric vehicles.

People have hard time grasping how much energy chemical bonds can hold. 15 gallons of gasoline store 500kWh of energy. That is 5 tesla model s worth of energy.

Efficiency plays role for our day to day car tasks, but when you have to deal with external forces or higher requirements of momentum, then you need more energy period. Towing, beating high-speed drag / waves, climbing high, cannot be addressed with smarter design. You need to be able to store somehow enough energy to deal with these external forces / additional required momentum

> 15 gallons of gasoline store 500kWh of energy. That is 5 tesla model s worth of energy.

Yes. However, the Carnot efficiency means that most of it is lost as heat. Suddenly the advantage is not that large anymore.

Not even close. An electric motor is 4 times more efficient than ice. An ice car can easily store 10 times more energy than an electric.

F150 can tow 13,000 pounds and has a 27 gallon tank (almost 10 Tesla’s).

Don’t forget to talk about rockets! Although there weight is more important than volume.

Volume matters too, especially for lower stages. There's a reason for the lack of success of hydrolox 1st stages.

ICEVs will outlast BEVs. Just like it did 100 years ago.

Hydrogen works fine in ICEs with modest modifications.

Hydrogen can be created with nearly any energy source: renewable, natural gas, etc.

There is a large infrastructure for moving fuels.

>Hydrogen works fine in ICEs with modest modifications.

Just that they get lower efficiency than a fuel cell version, and apparently are sensitive to load, so mostly suited to constant-load applications, which a car typically isn't. Otherwise it'd have been interesting as fuel cells also have some serious drawbacks and seem to develop very slowly.

> Hydrogen can be created with nearly any energy source: renewable, natural gas, etc.

Yes. Although efficiency is kind of bad, so it doesn't make sense to use fossil fuels to make H2 for cars - we'd just be increasing emissions as opposed to generating electricity for use in BEVs. H2 has its place as intermediate term (before batteries get cheap enough) energy storage of surplus wind and solar power. It makes more sense to use the H2 for other things than cars though - ships, trains, long-haul trucks, possibly planes.

>There is a large infrastructure for moving fuels.

Which I bet has to be seriously adapted to handle hydrogen. You wouldn't be able to move syrup with the existing infrastructure, because it's very different to gasoline. H2 is probably a lot more different - it needs much tighter seals, it embrittles materials such as steel, which is used everywhere for e.g. gasoline storage. It is cryogenic and under high pressure. Finally, it'd be stupid to lock ourselves into an energy storage tech that relies on a physical fuel that has to be transported around, when electricity is right there, partly built out already and requiring no physical trucks, trains, boats etc to get to the consumer. It's just stone age and the only reasons people think it sounds like a good idea is that they're so used to it working that way.

I wouldn't be so sure, I think there's a decent chance that e-fuel can be made economically viable.

Pure EVs will reach a fundamental peak percentage similar to any other car class... Hybrid powertrains are really where the next 20-30 years are headed for the bulk of vehicles. Automotive racing and supercars have demonstrated hybrids are the most effective setup for the past decade, and barring some major breakthrough in battery tech that will all trickle down into consumer cars over the next 0-20 years.

> Hybrid powertrains are really where the next 20-30 years are headed for the bulk of vehicles

It depends what you mean by 'bulk'. I see a major future here for big trucks-- right now, 99%+ of our long-haul tractor trailer semis are pure ICE. There is no way to fully electrify that fleet quickly, so I believe hybrid tech is being seriously underestimated in this space (especially for retrofitting).

I've been expecting to see this emerge for over 5 years, I'm not sure what's taking so long. Likely it's a catch-22 of the industry being resistant to change, while large chunks of (reluctant) investor funded R&D are necessary to make it viable. In any case, I think some larger scale tests are finally being run this year, so I'm looking forward to the results of that.

As far as consumer vehicles go, well... we should electrify almost all of it. Simply the best choice for the majority of use cases. But that's going to take a while, and will affect battery availability, which is all the more reason why big trucks will need a longer transition phase that hybrids are perfect for.

As soon as governments get serious about CO2 emissions, Hybrid powertrains will end up as a "worst of both worlds" position.

Already across most of Europe all subsidies and discounts that applied for "eco friendly cars" no longer apply to Hybrids.

That leaves few people wanting to buy a hybrid - it won't be cheapest or most eco friendly.

Not sure I agree with that. I don't think you realize how many cars have switched over to hybrid powertrains, but are not advertised as a main selling point like the Prius or Volt. Volvo's entire lineup is now hybrid or electric along with their new performance brand Polestar. Mercedes is switching over to hybrid powertrains even on their AMG models. Audi's using hybrid powertrains even on their highest performance models like the RS6 and their ultra luxury vehicles like the A8. Hybrid technology is great for sports cars and offers many advantages over fully electric, most importantly being the weight savings.

It definitely feels like you get some free low end torque in a hybrid as well.

I think the thinking on hybrids will shift from "smaller gas engine with an electric boost to help with merging on the highway" to "range extension option for the electric car." They'll be configured to not even fire up the gas engine until the battery pack is run down enough.

Hybrids are facing real challengers from a combination of PHEV, synfuel, hydrogen combustion and hydrogen fuel cell. While it is the ideal car of today I wouldn't be so sure about the next 20-30 years.

Those who are curious about the oval piston skirts may find this interesting: https://news.ycombinator.com/item?id=15397926

How were these animations made? They’re excellent!

He posted a bit of information on his Twitter:


I find this to be a very impressive implementation.

I wonder if it's completely written by hand from scratch or done with something like emscripten.

He said on Twitter that he hand-wrote the animation code.

Isn’t it risky for the timing to rely on a rubber belt? Does it never slip? Even a mm of slippage seems like it would make the valve timing stop matching the pistons?

In addition to what frosted-flakes said, many engines are “non interference” design so that if the belt snaps or jumps a tooth the engine won’t be destroyed, and the belt will just need to be replaced. However, non interference engines are not as compact as interference engines.

Many engines also use a timing chain instead of a timing belt, but this carries extra weight and requires lubrication.

It’s all about tradeoffs!

The engine in one of the vehicles I own has timing gears rather than a chain or belt. Another option, different trade-offs.

Much more common with pushrod engines, where the camshaft is situated close to the crankshaft; less so with overhead camshafts. Though I think some very high-revving sports and competition engines have gears driving overhead cams; IIRC the McLaren TAG F1 turbo V6 (by Porsche) back in the 1980s was one example.

The engine used in the Ferrari Enzo and Maserati MC12 is a notable example:


Yup, beautiful. The TAG/Porsche looked quite similar IIRC.

And, given your nick, the OHC Volvo B18/B20 can't go unmentioned: Dunno if this was standard back in the day or if it was unique to this engine, but it had an interesting combination of materials. The smaller gear on the crankshaft was steel, but the larger one on the camshaft was made out of some weird bakelite-like stuff; as I recall, with some sort of fibrous reinforcement in it.

(OK, if you're not a Swedish motor enthusiast, you may be wondering "WTF does my nick have to do with that?" A: The B18 was used in the Volvo Amazon.)

My first car would diesel after turning it off. Basically the engine would keep running on fuel in the carburetor and residual heat in the engine. Sometimes it would do this backwards. This was very problematic because the timing belt tensioner only worked in one direction. When it ran backwards the timing belt would jump a tooth then the car would not start. I got in the habit of just killing the motor with my foot on the brake and the car in gear then letting the clutch out.

I also had the machine shop at my high school weld up a custom tool to help me reset the timing belt in a parking lot with a couple of hand tools. It could be done in a few minutes.

This is a long way of saying yes, if they slip it is bad.

Yeah it’s one of those things that you just have to replace every X miles just to be safe. I got one replaced a couple of days ago because the service history was missing and I couldn’t tell whether it had ever been done. If your timing belt goes you’re in all sorts of trouble.

When I started driving German cars (may be coincidental) I noticed my mechanics would write the date and miles of the service directly on the parts.

My Toyota actually had a small decal on the timing belt cover itself specifically for the purpose of tracking that service.

It is risky and they do slip or even break from time to time. They are generally a 100k maintenance item. The alternative is a chain, which can also fail (or other related components), but is generally not considered a maintenance item.

The belts are finely machined to very small tolerances, and things are tightened to specific foot-pound tolerances to make sure they sit exactly where they need to. So no, nothing slips.

I just went through a belt change with my brother not long ago. The tolerances you're dealing with are measured in thousandths of inches. Something that wasn't installed quite straight can cause almost imperceptible wobble that can destroy things under load.

Still, every day shop tools will help you get the precision you need.

Rubber with embedded steel wire is less stretchy than the rubber bands we're used to. Tires even more so than belts; it adds integrity like rebar in concrete.

You're correct that once it jumps even 0.5cm (~1 tooth) it could touch piston to valve; it depends on the engine, but I'd wager most nowadays are interference.

Timing belts are toothed, and if installed correctly they will never slip. Modern kevlar timing belts are near-indestructible under normal use. The real problem is the pulleys—once those bearings wear out, they can seize, causing the belt to slip or even break.

Timing belts have teeth.

Occasionally chains are used instead; more expensive and heavier, but more durable. You do need to maintain the timing either way it it will destroy the valves.

If the engine is a non-interference design, losing the belt won’t be catastrophic for the valves

>Timing belts have teeth.

To expand: It is the teeth that make belts timing belts, they keep the 'timing' (relative rotational orientation) of 2 or more toothed pulleys. In an ICE the camshafts are locked to a 2:1 ratio to the crank shaft, in a 3d printer it keeps an axis fixed relative to the stepper motor shaft.

I think another reason belts are common is that chains tend to be a bit noisier.

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