Filed under: Green, I.C.E., Tech
Scuderi split-cycle engine almost ready for sale to automakers
Scuderi has been hard at work refining its split-cycle engine technology for the last few years, and the company believes that it's close to another milestone. Though still far from production, testing has recently validated an important aspect of the design involving the valvetrain, so vice president Stephen Scuderi believes that he is close to licensing the technology to other manufacturers.
The split-cycle engine is intended to be an improvement on the traditional Otto cycle and acts a bit like the Miller cycle. Instead of using a mechanical supercharger, though, the Scuderi design uses paired cylinders to compress air, which is then used to prevent reversion of the exhaust gases into the intake tract. It is also possible to store some of this compressed air to power the vehicle as part of a hybrid drivetrain. If this seems to make little sense (don't worry, you're not alone), click past the break for a computer rendering of the engine running.
[Source: Automotive News - Sub. Req.]
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Reader Comments (Page 1 of 2)
Will 3:18PM (4/19/2008)
"The air-hybrid engine is the first hybrid that makes sense."
As we say on the internets, PWNED!
It's a really interesting idea, but i'm wondering what kind of air pressures will be required.
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Cameron 3:18PM (4/19/2008)
But how does it sound!?
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Dan 3:21PM (4/19/2008)
Very cool. I think it would be a pain in the ass to get the timing right though.
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why not the LS2LS7? 3:35PM (4/19/2008)
A bunch of nonsense.
Sure, it fires at (er, after) TDC every time, like a 2-stroke. But it needs twice as many cylinders to do it. That means the same power as a 4-stroke with more complexity.
And look at either the energy storage (regenerative braking) or utilization modes. Each leaves one cylinder fully operating but doing nothing useful. That's a waste of space and friction.
Also, the energy storage mode is useless, because with a compression ratio of 10:1, you're only going to be able to produce air compressed to 147 psi. Any air-hybrid would thus need a truly enormous tank. If you want to store even a decent amount of energy with air, you need to get up into the hundreds or thousands of psi.
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Andrew Tanasescu 3:50PM (4/19/2008)
Your right on the money. I was honestly thinking the exact same things when I was watching the video.
I honestly cant see how the increase in moving parts can equate to increase in efficiency.
White Goodman 4:25PM (4/19/2008)
You're ignoring the massive amount of work required to compress a gas, which is the main focus of this engine and is magnitudes higher than frictional losses of an added cylinder. In general the additional complexity of a split-cycle engine would be tough to justify as a way to simply achieve better combustion efficiency, but with the added benefit of being able to transfer kinetic energy into compressive work, and to store that energy for future conversion to kinetic energy... that is where this split cycle technology is truly impressive.
So every time you slow down with this Scuderi engine, you are increasing the efficiency with which you develop kinetic energy in the future. Think about it this way: when you use your disc brakes now, you are turning your kinetic energy into heat energy which is wasted into the atmosphere. The split cycle technology would "recycle" that kinetic energy into compressing an intake charge so that the engine doesn't have to do that part of the 4-stroke cycle when it is called upon to combust again. Whether by simple air-hybrid locomotion or by using the already compressed gas for combustion, you eliminate the need to compress the intake charge each stroke which is a big gain in efficiency.
Additionally, since it seems that the intake charge is compressed prior to fuel being injected, the compression cylinder ratio could likely be much higher than what we normally see in today's ICE engines since one wouldn't have to worry about pre-detonation.
Sure the entire system is complex, but not more so than any other electric-hybrid currently in use-- probably less complex, actually.
AMcA 8:57PM (4/19/2008)
I think you're wrong about losses from the cylinder continuing to work when its valves are turned off. Yes, there's some moving parts friction, but no compression friction and no pumping friction. The air trapped in the cylinder just acts like a spring. Same thing we do today with displacement on demand engines.
why not the LS2LS7? 9:28PM (4/19/2008)
The energy recovery mode is a sham.
Lets assume that you have filled the pressure accumulator to the max pressure that the compression cylinder produces. In the case of a 10:1 compression cylinder, you're talking about 147 psi.
On the first energy recovery stroke (where you don't compress but instead get air from the accumulator), you get air at 147psi. But that begins to empty the accumulator. With every stroke from the 2nd, actually get lower pressure air than you would have received if you got the air (charge) directly from the first cylinder. So with each stroke during the energy recovery cycle, the engine produces less and less power.
This is just not useful.
zmf001 3:42PM (4/19/2008)
I'm all for new engine technology, but that looks expensive. Twice the number of precision balanced and machined components. It had better be a lot more efficient than a regular 4 stroke Otto cycle if they plan on selling it to the mass market.
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AMcA 9:18PM (4/19/2008)
Doesn't look at that expensive to me. More cylinders? No, I don't think you have to do that. A 4 cylinder would have two power cylinders. And I think it would run smoothly enough, as the compression cylinders would help balance the engine just the way more cylinders do in conventional engines.
Viktor 3:47PM (4/19/2008)
If I've understood things right then a 4 cyl scuderi-engine would be comparable to a 2cyl conventional engine when it comes to smoothness, sound and the overall feel of the engine since only half of the scudery-cylinders delivers power.
If that's the case and manufacturers would need to double the cylinder count then engine weight, size and especially the manufacturing costs would be a lot bigger.
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chrisdavis 10:45PM (4/19/2008)
What you are missing is that the power cylinder fires with the frequency of a 2-stroke, but uses two cylinders to do it, so you have the same number of power strokes/cylinder as you would with a conventional 4-stroke.
It doesn't seem less efficient, but I'm not seeing how it is more efficient unless the valvetrain is somehow simplified.
Ethan 6:14PM (4/19/2008)
No. Just... no. A four-stroke engine fires all cylinders every four strokes. The Scuderi engine fires half the cylinders every two strokes. So half the cylinders are firing, but twice as often as in a four-stroke engine, so that's ½×2. So it fires 1x as much as a four-stroke.
Yar 4:15PM (4/19/2008)
Just start putting 2 strokes back into cars. In Marine applications, Direct Injected 2 strokes have been delivering better fuel economy and lower emissions than their 4 stroke competitors. No reason not to try one in a concept car. This junk is nonsense.
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BigRedSpecial 5:07PM (4/19/2008)
Snowmobiles too... Skidoo's SDI and Etec engines have the best fuel efficiency and lowest emissions of all high performance engines, plus the highest power to weight. Even their new 800R engine is more efficient than the 4 strokes, despite having carbs. 151hp out of .8 liters is always nice too;)
Brad Kempeny 12:48AM (4/20/2008)
That, or develop a small displacement 2-stroke diesel similar to the engines used in locomotives. They have the inherent high power/displacement that a 2-stroke has, yet unlike a 2-stroke, it has gobs of torque. Utilizing DI, urea/catalyst particulate filters, you have one fine, clean engine.
why not the LS2LS7? 10:46PM (4/20/2008)
You're both insane. Even Orbital can't make a 2-stroke have the same emissions as a 4-stroke.
JayP 4:55PM (4/19/2008)
This looks like something Audi would build and make it impossible to have serviced.
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SilverAero 4:57PM (4/19/2008)
From what i see the energy needed to run the compression cylinder will out weight the benefits of having a supercharged combustion chamber. I'm not sure if this is an improvement over traditional super or turbochargers, plus the added weight. This would serve better as a gasoline powered air pump.
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bakka 5:07PM (4/19/2008)
Remember the gas turbine?
Then we had the Bourke engine,then the Wankel,Orbital,Stirling and a host of others that were supposed to do fantastic things of all sorts.
This one seems a bit complex,but only real world tests will confirm.
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