But today a 95% efficient generator connected to a 95% efficient motor for 90% overall transmission efficiency would be worth it on a turbine or Stirling engine running at 40-50% efficiency (maybe 40% overall at the wheels). Compare that with an old gas guzzler from the 70s running at 25% efficiency with maybe an 85% efficient transmission for 20% efficiency at the wheels. Not to mention that cars used to weigh twice as much which halved city fuel economy again, and lacked regenerative breaking which halved it again, and so on and so forth. It’s no wonder that cars used to get 10 mpg when what I would argue are relatively simple engineering changes could have raised that to 30, 50, even 100 mpg. It’s almost like they were deliberately designed to be as inefficient as possible…
Nit: this is actually the other way around, cars have been gaining weight - so much that it has swallowed most of the mileage improvement we'd otherwise have gotten from other tech improvements.
See eg http://newsoffice.mit.edu/2011/cars-on-steroids-0104
When Rocky Mountain Institiute was working on their hyper car concept, I believe the researcher said that weight reduction was more important than electric or gas engine.
I think he said something like for every pound you save, you actually reduce an extra 2-3 pounds of supporting materials elsewhere. Lighter cars need less HP, you can reduce some of the support bracing as it's not as heavy of a vehicle, etc...
Making cars super light would do a lot of good and so every time I see a giant battery for electric cars or a 2nd engine to act as a backup, I wonder how much that is costing in terms of weight and MPG.
The problem with most electric cars right now is range, which is due to the inherent cost of the batteries. But it's largely psychological, as most people's driving in most situations is within the range of a reasonable electric vehicle. It's just exceptional circumstances when it's not enough.
Thus, paradoxically, adding a gasoline range extender to an electric car could really help enable electric driving considerably. And if the car drives 90% on electricity, the efficiency of the gas engine doesn't matter too much. It's just there as a backup.
I almost bought a plug-in hybrid last year. A Volt or similar would let me do a ton of pure electric driving, while still having the option to go farther. A Leaf or similar just wouldn't cut it for me, because a car that covers 90% of my driving isn't good enough. But if it can cover 100%, with 90% on electricity, that's a big gain. Ultimately I didn't get one, because they're still a bit too compromised (the Volt only seats 4, others have tiny cargo space), but range extenders could be an important bridge measure as batteries slowly improve, and the extra weight isn't all that important in many cases.
Are you sure about that?
According to , "To ignite a stoichiometric air-fuel mixture (14:1) approximately 0.2 milliJoules of spark energy are required. Very rich or lean mixtures can require as much as 3 mJ."
So yea, not much...
In this new motor there's nitrogen on the other end of the piston that provides "rebound". It's probably inside the coolant jacket as well to prevent expansion and the loss of efficiency that would bring.
Wonderful cars. I'd buy an RX-9 if they ever built one, but they're never going to. So I have to motorcycle instead, could be worse :-)
Loved how it handled and the 9,000 rpm redline.
One of my cats is gutted and my exhaust is rusted to hell - right now my fuel economy is shit (~10mpg). This should actually improve when I put the Racing Beat exhaust in but then I have to upgrade the injectors and air intake and port the turbo.
My 10th Anniversary is still bone-stock and I'm sad about having to change it.
If you actually maintain your car and don't treat it like a toaster, it's not too bad. They combust oil to lubricate the engine, so you just have to make sure it has oil. If your oil metering pump is electronic ('89 and after), run it with premix when you fill up. And drive your car hard & rev past 6k once a drive or so to clear out the carbon. Yes, I've gotten a speeding ticket for doing this.
I love my car. It's about to hit 100k miles and it's a Turbo and despite what the naysayers say, it hasn't blown up yet and still has good compression.
The electrical issues are far worse than the engine ones. The engine is bulletproof if you do your basic maintenance and listen to your car.
Every sports car is high maintenance. The Alfa, Porsche and Ferrari owners have it as bad or worse - people just treat exotic powerplants like voodoo - I sure paid a hell of a lot less than they did though.
I would rather pull and rebuild my entire engine than change the power steering fluid on a recent Porsche. The latter has a nightmarish set of steps likely to break all sorts of tiny plastic bits that cost more to replace than my engine rebuild kit would...
This. Never forget basic maintenance. I had a 1981 RX-7 and had over 194,000 miles on it when I got rid of it in 1998. (I still have the concrete blocks I'd put in the back when it snowed.)
But generally you want to avoid buying an '04-'06 RX-8 used.
After the '06 model year they went to 3 per rotor and angled third nozzle to compensate.
That's how I understand it from the reading I've done and conversations with mechanics & owners I know. I've yet to work on one of these with my own two hands. I'm strictly interested in 7s and earlier. I inspected a few 8s for potential purchase but they all had problems that I wasn't interested in dealing with.
What problems does the 8 have?
What I talked about earlier is the main problem for RX-8s. Beyond that they're about as reliable as other cars of the same era and classification. They do come with about as much performance as you can get out of them from the factory though. They're not that interesting as anything other than a street cruiser.
Just like spun rod bearings and thrown rods are for Subaru owners, amirite?
At least when a seal goes, I can replace the rotor, walls and side housing; if it even needs that.
A gas spring is a pretty simple mechanism and can't misbehave (too bad you can't put it to work, though -- probably a lot of heat being wasted compressing it).
Of course many people have thought of this before (don't you hate it when that happens! ;0)) - http://www.youtube.com/watch?v=2SlwoBLspTQ shows 2 such engines.
http://www.youtube.com/watch?feature=player_detailpage&v=yV0... shows another idea, 2 pistons either side of a single combustion chamber.
It's not, in a closed system momentum is conserved  so without friction, a free engine would rotate forever.
Also there is not conceptual difference between an engine and a ball sniping in a donut. In both case, the piston or the ball have to change direction (the piston has to change direction more abruptly though)
Just think of any spot on a wheel representing an arbitrary amount of mass. Spin the wheel, and the only thing slowing it down is friction -- not that spot constantly changing direction.
source : https://www.iter-india.org/images/fusion_experiments2.jpg
Energy output to generate electricity is quite indirect: hot neutrons escape the magnetic containment and are caught in a lithium blanket. This produces tritium from the nuclear reaction between the neutrons and lithium nuclei, and heat. The blanket is cooled with water which is used to drive a conventional steam turbine generator set.
See the last paragraph of the reactor overview at http://en.m.wikipedia.org/wiki/ITER and note that they do not plan to generate electricity from ITER: it is purely experimental.
The crankshaft works as a (cheap) synchronizer for piston movement and can reduce vibrations when phases are aligned in special way.
Motor vibrations are big deal - they take energy and also reduce quality of car.
Even better, a two-cylinder FPEG is inherently balanced
I guess electronic timing is also up to the task of keeping things running smoothly without mechanical synchronization.
Given the current popularity of hybrid hyper-cars from Porsche, McLaren and Ferrari it would be interesting to see if something like the Jaguar is tried again.
This was quite literally a lower power jet aeroplane turbine used to power the car.
I would imagine that this would have been great on fuel economy on the highway, but terrible in cities.
Still pretty cool though!
Small turbines generally have terrible fuel economy. The Wikipedia page you quote says "...fuel consumption was excessive"
If I remember correctly about 3 to 1, compared to 10 in 1 for petrol engines and nearly 20 to 1 for diesel engines.
Thermodynamically this makes it very difficult to achieve high efficiency.
That seemed strange to me given multistage compressors. Maybe 3:1 is true for a micro turbines, but for larger jets wikipedia says the pressure ratio is 30:1 to 40:1 citing the Trent 900 at 39:1 and the GE90 at 42:1.
Which according to the same article says that a 40:1 PR is equivalent to a 15:1 compression ratio.
You mean, like a turbine?
I think he means like a Wankel engine:
There are rotary internal combustion engines, such as the Wankel engine. It has a triangular "rotor-piston" spinning in a circular cylinder and goes through four "strokes" per revolution.
Mazda is a manufacturer that utilizes rotary engines in production cars today, particularly in their high performance models.
(at least, for production consumer vehicles)
Is 15 HP really enough to move a car at highway speeds? I had a CBR250 motorcycle that produced 22-24 HP and weighed around 350 pounds, and it was not particularly great on the highway. It's hard for me to imagine a car that's 3+ times heavier with less horsepower being safe on a highway.
It's only when you get up to large scales that they start making sense.
Second, and this is admittedly more long term, it doesn't really matter what type of engine you put into the Volt. This thought was presented to me by one of their dealers, but it makes a lot of sense. The current engine is a "tried and true" gasoline job. But if Chevy found that diesel or bio fuel, or natural gas worked better, they could swap it out without redesigning the rest of the drivetrain.
I may sound like a walking billboard for the Volt, but I am honestly not. I don't own one, and do not work for Chevy/GM. I do happen to think that the Volt is the best compromise between price, range on batteries, and ability to drive long distances. While Tesla's are very cool, I think the Volt is a much more gradual transition from gas to electric.
The article's point is not to about "diesel-electric" systems (where the ICE acts solely as a prime mover for a generator and the wheels are always driven electrically). That's old news in both transportation in general (it's been in use in trains and ships since the early 20th century) and in hybrids ("diesel-electric" is sometimes called "series hybrid" or "range-extended electric vehicle" in cars).
It's about a new engine design where electric generation is merged into the piston itself: a "normal" diesel-electric engine has a regular diesel engine (or more generally ICE) with pistons driving a crankshaft which drives the driveshaft, which is connected to a generator.
Here the design does away with the crank and driveshaft: the piston itself is a rotor, and the casing becomes the stator, doing away with mecanical transmission altogether: the piston and its cylinder become a linear generator.
 not quite that new, the first patent on free-piston engines for linear generators dates back to 1959. The new part is getting a design to actually work in a vehicle.
 a free-piston engine is an engine without a crankshaft transforming the piston's linear movement into rotational movement
 the crankshaft does not just transform motion and lose energy, it also synchronises pistons and limits the piston's course. But if the piston+cylinder is a self-contained generator, I guess you can treat each piston as a single-piston linear engine? Which would limit the usual issues of multiple free-piston engines.
edit: formatting, footnotes
Also, I'm not sure about the current model, but there was a bunch of kerfuffle over the Volt not really being a strict electric hybrid:
Some of the time, at least in the edition discussed there, energy from the engine goes to the wheels without ever becoming electricity. Maybe they changed it in later models (but I sort of doubt it, the capability is there because it can be the most efficient way to use the engine).
In either case, I am not a purist going after a 100% electric car. I want to get more miles per dollar, and I want to produce less CO2 per mile. The Volt seems to do that, while still letting me drive from NYC to LA and back without having to spend more than three minutes at any given gas station. More importantly, any gas station will do, since it can run on just gas. For a daily commute, it will likely run 100% electric since the battery won't be depleted. To me, this is a great combination.
There are some interesting consequences of a pure serial hybrid design like the Volt (although the Volt isn't quite a pure serial design), but friendlier RPM and the ability to shut the engine down aren't it.
Now, what to do with that liquid in that 15 gallon tank is a question, but the basic fact remains. Did I mention that that fact is simple? A car needs energy, and that 15 gallon tank is tough to beat. For the rest, we have a lot of possibilities, but that 15 gallon tank is tough to beat.
So, let's look at an example, say, Tesla. I just went to their Web site and looked at charging time and saw
> During the work week I charge only at work during an 8hr shift from a 110 outlet. I only live 6 miles from work. I usually get ~30 miles of charge in 8 hours
So, right, 8 hours of charging for 30 miles of driving. Lots of cars can go 30 miles on one gallon of gasoline that takes about, what, 20 seconds, to pump. Diesel, maybe 45 miles.
The car, sure, it can still drive the wheels with electric motors, but, to make any sense, we store little or no electric energy in the car. Instead, the energy for the car is stored in a 15 gallon tank of gasoline or Diesel.
We had electric cars going way back to the beginning of cars. Why? Because lead acid batteries and electric motors were already old things. And, a battery much better than lead acid is still tough to get; indeed, we still use lead acid batteries in cars for, say, the starting motor.
The main problem with electric cars remains the batteries. As a Ford executive said long ago, build me a good battery and I will build you a good electric car. We are still waiting for a good battery, say, comparable with a 15 gallon tank of gasoline, in range, capital expense, operating expense, durability, and 'recharging' time.
So far, a Tesla is a toy for rich people. Sorry 'bout that.
I could like an electric car; it would have a lot of advantages. The problem is the battery. And that's been the problem for about 100 years.
I imagine the people clicking the down facing triangle were responding to your unnecessary and out of place tone, not out of Tesla exuberance.
> Nothing in the grandparent comment invites your first rant.
Wrong. From the OP I was responding to:
> Electrically driven cars are the future. But until we have cheap, 1000-mile batteries, we still need range-extending fossil-fuel engines.
This quote is the "rant" -- the writer hates "fossil-fuel engines" and is dreaming of "1000 mile batteries" presumably to be charged from the electric grid. Wacko nonsense. Smoking funny stuff nonsense.
Uh, just where would the energy to charge a "1000 mile battery" come from? Sure, now, heavily from the electric grid from fossil fuels. Wind, solar? Nope, not for the grid because those sources will need to store electric energy, and that's too darned expensive.
Some people just HATE a 15 gallon tank of gasoline or Diesel and just dream of "1000 mile batteries" and threaten to increase my costs of car travel and seriously weaken the US, and I don't like attacks on either me or the US.
This wacko, 'green worship' with humans and carbon as 'evil', etc. is going too darned far. I don't care about people worshiping the moon, but this wacko stuff is trying to hurt my car transportation, and I don't like it.
They also don't actually say the words you have put in quotation marks, or anything especially dreamy about electric cars. Maybe they said it somewhere else?
(I suppose 'less carbon' could be characterized as dreamy, but electric miles are often cheaper to operate, so I guess I don't like that characterization)
Anyway, I don't mind if you agree with me about whether the comment invites your response or not, I just wanted you to consider that maybe the people who inspired your second rant did understand your comment and downvoted for other reasons.
The original post is the article
Jason Cammisa, "No crankshaft, no problem: Toyota's free piston engine is brilliant: Gas piston engine fundamentals haven't changed in 134 years—until now.", 'Road and Track',
June 30, 2014.
and the third paragraph starts with just what I quoted,
exactly, again, yet again, one more time, exactly,
precisely, every character right in place:
> Electrically driven cars are the future. But until we have cheap, 1000-mile batteries, we still need range-extending fossil-fuel engines.
Again, the work by Toyota looks good, and the article is somewhat interesting, but apparently the author wanted to insert a line to please the greenies so put in his "1000-mile batteries" and his swipe "fossil-fuel". Apparently with a little more encouragement he could have put in some words about evil humans and filthy CO2 and the dangers of 'global warming', rising sea levels, massive deaths of wildlife, the melting of Greenland, and 'climate change', that is, each tornado, hurricane, flood, drought, snow storm, especially hot/cold day, week, season, etc. I'm SICK of nearly constantly being beaten over the head for no good reason by this non-stop propaganda of total incompetent, made-up, hysterical, guilt-ridden, dysfunctional, destructive, dangerous nonsense.
This propaganda is trying to build a political consensus to get on my back and into my wallet and seriously hurt the US, and I don't like it.
I don't know who or what is paying for or pushing this propaganda, but I'm pushing back at it.
They also don't actually say the words you have put in quotation marks,
My bad substituting "carbon" for "CO2".
For the guy with his Chevy Volt, fine.
I also think it would be more useful to post a thoughtful, persuasive comment (as opposed to saying 15 gallons multiple times), but that's a different issue.
Anyway, this whole sub thread is sort of unfortunate (in that we both wasted time and any unfortunate bystanders wasted their time too). Oh well.
The 15 gallons thing is because I'm pissed at this greenie stuff and need to pound and pound on the rock solid, dirt simple, overwhelmingly important fact that the whole greenie thing is trying to beat a 15 gallon tank and has essentially no chance of doing so and, thus, is really dumb and much of why I'm pissed. I continue to be attacked here because of 15 gallons, and that shows again, yet again, once again, over again that even something as simple as a 15 gallon tank is unacceptable to the greenies so devoted they are to their irrational religion. The greenies can go worship the moon and I won't care, but they are a threat to my car and to the strength of the US, and I'm pissed, as nearly everyone in the US should be. This greenie stuff is wacko.
You aren't getting attacked because you said 15 gallons though, people are down voting your posts because they don't add much to the conversation. You're imagining some motivated contingent of people voting against your posts because they speak the truth about the article, but really, your first post was down voted because it was somewhat obnoxious.
I mean, are you commenting here because it is a convenient place to propagandize, or are you commenting here because some decent and interesting conversations take place? If it's the latter, then you have a reason to make a better effort than making sure that your views get equal time propaganda. I realize that sounds preachy, but I'm too lazy to figure out how to better put it.
Why'd you use a car then? That's a very nice bike ride. (I'm from The Netherlands so excuse my ignorance if there isn't even a physical way to bike around your area).