
Turbulent times for Formula 1 engines result in unprecedented efficiency gains - nkurz
http://arstechnica.com/cars/2016/05/turbulent-times-for-formula-1-engines-result-in-unprecedented-efficiency-gains/
======
MrFoof
Another trick Formula 1 has had for a while, that will soon be seeing adoption
into production cars, are camless engines. Valves are operated by
electronically-controlled pneumatic actuators. This allows the valves to open
and close faster, and makes intermediate states (in between fully closed and
fully open) a lot easier. It's also a major reason as to why crank speeds are
as high as they are in F1 cars, as they valves can be actuated fast enough to
avoid the valve float that would otherwise occur in cammed engines with valve
springs. Production cars currently tend to top out around 9450rpm (the 6.3L
V12 in the LaFerrari), whereas Formula 1 cars have pushed close to 20,000rpm
(though usually 16,000 - 18,000) for quite some time.

Supercar manufacturer Koenigsegg is in the process of licensing their consumer
version of the technology under the trade name "Freevalve". They've been
developing it and testing it for an incredibly long time (I believe it's in
its fourth or fifth generation), presumably to keep driving the costs down. I
believe a few Chinese manufacturers are some of the initial companies signing
on. It's around a 3-4% efficiency gain on its own.

There's other fun stuff too, like Mercedes-Benz's split turbochargers.
Basically, the turbine is located near the exhaust still, but a shaft runs
through the engine to the other side to the compressor which is near the
intakes -- less piping to get a cooled charge, less turbo lag (again, shorter
piping), a more compact engine footprint, and needing smaller intake side pods
than using normal turbochargers. Be interesting to see if those trickle down
to consumer autos, whereas currently manufacturers are instead integrating 48V
electrical systems for electric turbochargers (and more advanced lighting,
hybrid functionality, etc.)

~~~
avs733
>Another trick Formula 1 has had for a while, that will soon be seeing
adoption into production cars, are camless engines. Valves are operated by
electronically-controlled pneumatic actuators. This allows the valves to open
and close faster, and makes intermediate states (in between fully closed and
fully open) a lot easier. It's also a major reason as to why crank speeds are
as high as they are in F1 cars, as they valves can be actuated fast enough to
avoid the valve float that would otherwise occur in cammed engines with valve
springs. Production cars currently tend to top out around 9450rpm (the 6.3L
V12 in the LaFerrari), whereas Formula 1 cars have pushed close to 20,000rpm
(though usually 16,000 - 18,000) for quite some time.

Sorry to be a buzzkill but this is not correct

The engines are not camless. However, they are 'spring less' in a traditional
sense. In the early 1990's the typical wound wire springs were replaced with
pneumatically charged cylinder that functions as the spring. The reason was do
to the inability to create wound wire springs that did not encounter harmonic
issues as RPM went up and a more efficient valve closing action. However,
through all of this, the camshaft itself is retained.This allowed engines to
reach over 20k rpm (which sounds unreal) but the current regulations,
introduced in 2014, limit them to 15k and they typically run less due to rules
that limit fuel flow at higher RPMs.

The Koenisegg on the other hand is absolutely camless technology they call
Free valve and it is a marvel. It not only allows control of the profile,
overall, but a on a cylinder by cylinder valve by valve basis.

Similar thing with Mercedes' turbo charger. It is split, and it is impressive,
but the benefits are more complex simply gaining from placing the compressor
and turbine at different ends of the engine (e.g., moving intake charge away
from exhaust heat, providing space for an ultra highspeed motor/generator on
the turbo shaft) etc.

At the risk of sharing clickbait...there is an argument that current F1 cars
are more energy efficient than a tesla
([http://www.espn.co.uk/f1/story/_/id/15152695/f1-cars-more-
ef...](http://www.espn.co.uk/f1/story/_/id/15152695/f1-cars-more-efficient-
latest-tesla))

~~~
ckozlowski
>there is an argument that current F1 cars are more energy efficient than a
tesla

It does sound like click-bait, but I see the point they're making there. No
one is proposing we all drive F1s, but for that performance regime, under
those conditions, F1 is more efficient with it's energy usage in achieving a
target output than a Tesla would be. I'm sure that decreases dramatically
driving at pedestrian speeds.

It reminds me a bit of when I first read about the SR-71's J58 engine. I'm
trying to remember where I saw it (I think it was in the book "Skunk Works")
in that the SR-71 was actually most efficient running at Mach 3.2 than it was
running at lower speeds. Seems counter-intuitive, but like F1, that was the
situation for which it was designed.

~~~
nopzor
Yes, the SR-71 was happiest at mach 3+. At these speeds, metal expansion due
to heat would seal the airplane frame up too. Designed for its mission.
Insanely, it would literally leak fuel on the ground.

------
Animats
It's not yet clear if the added complexity will be worth it for ordinary cars,
but it's interesting. 47% efficiency from an IC engine is impressive.

Formula 1 is deliberately power-limited. But the Formula 1 technical rules [1]
for the powerplant are all inputs, not outputs:

    
    
        Engine cubic capacity must be 1600cc.
        Crankshaft rotational speed must not exceed 15000rpm.
        Fuel mass flow must not exceed 100kg/h.
    

So that's where the drive for higher efficiency comes from.

[1]
[http://www.fia.com/file/40961/download/14591?token=5zH5vGzI](http://www.fia.com/file/40961/download/14591?token=5zH5vGzI)

~~~
rurban
Exactly. F1 engines can easily turn up to 24.000 rpm, but are limited to
19.000rpm to help the smaller engine teams.

------
venning
The plasma jet injection thing sounds pretty novel, but I imagine a lot of the
efficiency gain is tied up in the lean burn. The brake thermal efficiency
gains of lean burn are well known, as are the reasons we don't use them in
modern road cars.

Burning so little fuel in so much air produces high levels of nitrogen oxides
[1], bad for smog and acid rain and ozone. That's not a concern for an F1 car,
but a serious issue for road cars that need to pass emissions tests since they
can cause modern catalytic converters to stop functioning properly. See this
note [2] on how unhelpful current NOx mitigation strategies have been.

I believe the addition of three-way catalytic converters was partly
responsible for the stagnant fleet fuel efficiency somewhere in the 1980s,
since they had to make engines run richer than before to not foul the cats;
though, we've since developed better converters. (Also, safety equipment and
luxury things increasing weight affected fleet numbers.)

[1] [https://en.m.wikipedia.org/wiki/NOx](https://en.m.wikipedia.org/wiki/NOx)

[2]
[https://en.m.wikipedia.org/wiki/NOx_adsorber#Market_use](https://en.m.wikipedia.org/wiki/NOx_adsorber#Market_use)

~~~
venning
Following up, it looks like Mahle has actually been tying to address the NOx
production. The OP links to this article [1] from 2010, which is mostly taken
from three SAE papers that indicate they have been able to constrain the NOx
in jet injection engines to "single digit ppm engine out NOx emissions" [2].
The EPA seems to indicate [3] that less than 1 ppm NOx post-catalytic
converter is targeted. I don't know if their advancements allow for three-way
catalytic converters on a lean burn engine, but that would be pretty
impressive.

[1]
[http://www.greencarcongress.com/2010/10/tji-20101027.html](http://www.greencarcongress.com/2010/10/tji-20101027.html)

[2] [http://papers.sae.org/2010-01-2196/](http://papers.sae.org/2010-01-2196/)

[3, PDF]
[https://www3.epa.gov/ttncatc1/dir1/fnoxdoc.pdf](https://www3.epa.gov/ttncatc1/dir1/fnoxdoc.pdf)

------
aidenn0
Any mention of the Prius using the Atkinson cycle brings out the inner pedant
in me. I suppose to a certain degree, Toyota makes the engine, so they can
call it what they want, but late intake valve closing is clearly quite
distinct from the engine Atkinson invented (and indeed that design might not
have achieved one goal of Atkinson's engine which was to circumvent the Otto
cycle patent).

Indeed, if there were any existing cycle for which it would make sense to name
the Prius' engine after, it would be the Miller cycle, though that has always
meant some sort of external compression of intake air (the original patent
used a turbo, but all Miller cycle engine's I've ever seen have
superchargers).

One other interesting note is that the Miller cycle works best with a
supercharger due to increased relative boost at low RPMs, where the drop in
torque due to the late intake valve closing hurts the most. The Prius nicely
sidesteps this by using an electric motor at low speeds.

~~~
mrfusion
I'm not understanding the Atkinson cycle. It seems like less compression would
be worse. What am I missing?

~~~
Gravityloss
There are limits to compression. The fuel-air mix will combust spontaneously
if you compress it too much.

So that's why max compression ratio is something like ten. So a normal engine
has compression of ten and expansion of ten.

A more efficient engine with a different cycle might still have compression of
ten but expansion goes up to say eleven. This means it's possible to extract
more power at the end of the power stroke.

There are some tricks to achieve that. Toyota does it by creating an engine
with a geometry that would otherwise have very high compression and expansion
ratio, but they can avoid the high compression ratio: they don't close the
intake valves when the cylinder has been sucked in full of fresh air, like in
a normal engine. They keep them open so at the start of the compression cycle,
fresh air flows backwards out of the cylinder for a while, before they close
the valves.

~~~
ThenAsNow
Actually, the advantage of the Atkinson or Miller cycles is not due to
avoiding autoignition limits. Rather it is because of, as you pointed out, the
greater than unity ratio of (expansion ratio)/(compression ratio). So you are
improving the ratio of work that can be extracted from the power cycle as
compared to the work that you are doing on the mixture.

For the same engine displacement as a standard Otto cycle engine, the maximum
power you can develop with the Atkinson-type cycle is decreased, hence you
trade efficiency for power density. The Miller cycle approach is a way to
shift that balance back toward the Otto range by doing some precompression on
the air.

------
quahada
Reminds me of this article from 2004 of one person making similar innovations
as entire engineering teams with huge R&D budgets 12 years later.

[http://www.popsci.com/cars/article/2004-09/obsession-mr-
sing...](http://www.popsci.com/cars/article/2004-09/obsession-mr-singhs-
search-holy-grail)

~~~
pmontra
Interesting. He has a website now [http://www.somender-
singh.com/](http://www.somender-singh.com/)

------
maxxxxx
It would be nice if Formula 1 would be a test bed for advanced technologies
again like they did in the 90s with sequential automatic gearboxes.

------
thenewwazoo
I wish this article had more detail. Their description of the technology
sounds a lot like stratified charge engines, which have been around for a
long, long time... as in the Honda CVCC (the '70s forerunner to the Civic).

Perhaps the difference is DI?

~~~
ThenAsNow
It is very similar in the basics. A mixture that may be too lean to ignite via
spark ignition can nonetheless sustain combustion if it is "hit" with enough
ions, high-energy molecules, or radicals. Hence the "pre chamber" which
initially ignites a richer mixture with a low ignition induction time.

The difference between what is discussed here vs. the CVCC seems to be
principally about the kind of precise control that we can achieve using
today's technologies, including electronic control and micro-machining. From
there, it looks like the shaping and direction of the combusted jet from the
pre-chamber has been well-optimized in comparison to systems like CVCC.

------
ksec
Great! May be I am the only one in the nerd cicrle who dont want ICE cars to
die and Electric cars to take over. I want, better and hugly more efficient
engine along with cleaner fuel.

In the comment section someone pointed out about vaporized fuel achieving much
higher efficiency, why is that not being used?

------
revelation
This is the sort of massively twisted world we end up with when externalities
are not accounted for properly. Capitalism just spent in excess of 100 years
and many trillions of hours to come up with hilariously convoluted designs
still lagging massively behind the electric motor.

~~~
largote
Good luck trying to make an electric car last 200+ miles at F1 race speeds.
The technology for an electric F1 car just isn't there. Formula E is making
advances in that regard but it's just nowhere near the level of F1 ATM.

~~~
akira2501
> Formula E is making advances in that regard but it's just nowhere near the
> level of F1 ATM.

A Formula E car can't even make it through a single race.

