Scuderi Split-Cycle Engine To Go On Sale

By Jonny Lieberman
April 18, 2008 -

Last month we told about Ricardo's 2-Stroke/4-Stroke breakthrough, a very promising technology for sure, but one that is still just a series of gleams in a bunch of engineers' eyes. Much closer to prime time is the Scuderi Group's Split-Cycle engine. How close? Motor Authority is citing Automotive News who's claiming Scuderi's tech will be for sale within 12 months. This is big news, as the Split-Cycle internal combustion engine will be 40% efficient, compared to regular 4-cycle mills which are only 33% efficient. Scuderi is also promising lower emissions of NOx. So, how's it work? Just like it sounds, actually. The four-strokes of the Otto-cycle are split across two cylinders. One cylinder is used to compress the fuel and then "gas passages" move the compressed mixture into the detonation or power cylinder. The fun comes when you start playing with the bore and stroke of the various cylinders. For instance, you can make the power stroke longer than the compression stroke to take advantage of the Miller Effect (less energy is used by the compression cycle than the power cycle). Or you can increase the size of the compression piston to in effect supercharge the fuel mixture. We say not a moment too soon, as clean alternatives continue to (not) sputter along.

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20 Responses to “ Scuderi Split-Cycle Engine To Go On Sale ”

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Joshvar :
April 18th, 2008 at 12:32 pm

More news along these lines, please :D
CarShark :
April 18th, 2008 at 12:48 pm

I’m kind of surprised that as old as the ICE is, there is still room for serious innovation.
jaje :
April 18th, 2008 at 1:07 pm

Why not use what Mazda did with it’s miller cycle engines - use a supercharger to gain that effect.
bunkie :
April 18th, 2008 at 1:44 pm

I’ve been thinking about this all morning. First, wouldn’t frictional losses from the compressor piston offset a fair amount of the efficientcy gain? Second, if you need to double the piston count, you’re adding both size and weight and I really can’t see that being acceptable these days.

Finally, if you’re going to compress the air, why not just use some sort of totally external compressor? I could imagine having a turbine compressor to supply a constant volume of pressurized air to an accumulator tank. I’m sure there are a lot of reasons why this would be impractical (cost would be one of them), but it would be great to have a source of bleed air to run accessories.
Blastman :
April 18th, 2008 at 1:58 pm

Here’s a link to the animation that shows how it works …

http://www.scuderigroup.com/technology/animations/split_sideview.html
Jonny Lieberman :
April 18th, 2008 at 2:16 pm

bunkie:

Great questions and I wish I knew more about it.

I’ll assume the answer to the added size and weight and friction is that the engine is so much more powerful/efficient that those losses are covered and there are still gains.

Now, combine this split-cycle with elctro-magnetic valves and… ICE hey day!
bfg9k :
April 18th, 2008 at 3:38 pm

# bunkie :
April 18th, 2008 at 1:44 pm

I’ve been thinking about this all morning. First, wouldn’t frictional losses from the compressor piston offset a fair amount of the efficientcy gain?

Finally, if you’re going to compress the air, why not just use some sort of totally external compressor?

I don’t know too much about this, but from what I understand computer models have still shown a net gain in efficiency even with the 2nd set of pistons. The reason not to use an external compressor is because piston technology is very mature and the Scuderi engine could be manufactured on existing equipment.

An external compressor is exactly what’s used by a Miller cycle engine, with a supercharger.
alex_rashev :
April 18th, 2008 at 3:56 pm

As far as weight, note that this is techically a two-stroke motor with double set of pistons, so in effect your extra piston weight is offset by the fact that each one of them does twice the work of a 4-stroke.

I’m pretty sure that this requires FAST direct injection in order to work efficiently, in order to prevent fuel from leaving through the exhaust. Also, it would be a nightmare to do closed loop emissions control on.

Speaking of fast direct injection, a plain old Wankel would be a better recepient here.
Derek :
April 18th, 2008 at 3:59 pm

I second Joshvar. Send more news long these lines.
bunkie :
April 18th, 2008 at 4:02 pm

bfg9k-

Thanks. I’m thinking that a typical piston compresses air much more than any turbo or supercharger, which is why I was wildly fantasizing about a turbine compressor.

The crazy picture that came to mind was the opposite of the 1930s Italian attempt to create a jet engine by using a piston engine to drive a compressor whose compressed air was fed into typical jet combustor. Can’t remember the name at the moment, but it did actually work in that they built a flying prototype, but weight, perfomance and fuel consumption were all too poor for the idea to really take off.

In any case, it’s fun to speculate!