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http://www.cleanmpg.com/photos/data/2/European_Union_Flag.jpg the five-stroke engine might be a great stopgap between current technology and the Next Big Thing (http://www.wired.com/autopia/2009/08/five-stroke-engine/)

http://www.cleanmpg.com/photos/data/501/5-stroke_engine.jpgKeith Barry - WIRED (http://www.wired.com) - 08/21/09

this design is a 'thinking outside the box' idea --Ed.

The four-stroke engine has dominated internal combustion for more than a century, but a British engineering firm is ready to topple that technology with what it calls a 150-horsepower “five-stroke” engine said to offer the fuel economy of a diesel without the particulate emissions.

Ilmor Engineering, a firm that is co-owned by Roger Penske and supplies Honda engines to the Indy Racing League, spent almost 20 years developing the three-cylinder engine. Two cylinders operate on the conventional four-stroke cycle and empty their exhaust into a third low-pressure expansion cylinder, which allows the expansion and compression processes to operate independently. The prototype engine was first displayed at the 2009 Stuttgart Engine Expo, and its being readied for real-world, under-the-hood testing.

The Otto cycle four-stroke engine has pretty much been the standard for 132 years, but the five-stroke engine might be a great stopgap between current technology and the Next Big Thing.

According to Ilmor, the 0.7-liter engine is capable of 150 brake horsepower and weighs 20 percent less than engines with a similar output. Brake specific fuel consumption of the prototype is 226 g/kWh, which is a 10 percent improvement over current four-stroke technology. Even better, Ilmor says the technology is “100% conventional” and doesn’t require any new manufacturing techniques.

Ilmor says that the prototype five-stroke engine, based on a design by Gerhard Schmitz, has an overall expansion ratio “approaching that of a diesel engine – in the region of 14.5:1.” Along with its light weight and relatively high output, the extra work done in the low pressure (LP) cylinder provides for better fuel economy.... http://www.wired.com/autopia/2009/08/five-stroke-engine/

0.7 Liters and 150 HP? Wow! Although not unexpected from a firm that delivers race car engines to teams.

Very impressive!...0.5L for extra economy anyone? :D. I used to think my 2.5L was small...Now I feel completely obliterated by the fact that and engine less than 1/3 the size of mine produces just 13 less hp.

Food for thought:


2000 5-speed Honda Insight 995cc gas engine: 67hp (excluding 13hp electric motor)
5-speed Honda Insight with transplanted 1.2 liter TDI engine: 94hp
700cc 5-stroke engine: 150hpImagine the results!

600 cc 4 cylinder motorcycle motors-dead stock, not racing motors-make about 108 HP at the rear wheel which is maybe 130 hp at the crank.
The power output of this motor isn't exceptional-same as a conventional motorcycle engine.

Of course those 600 cc motors spin to close to 15000 RPMS and probably make peak power at 12000rpms or so(just guessing since I don't follow then closely anymore).These motors get terrible FE of course-under 40 mpg in normal use with total weight of maybe 650 lbs with a 210 lb human rider.

I assume that the grams per KWHr produced -roughly 300 mls per KWHr is good. I think that is roughly 12.5 KWHR per gallon?? 1000mls x 1/300 x3.78=12.5 KWHrs per gallon??

Didn't steam engines reuse lower pressure steam?
Charlie

Motorcycles do make that power at much higher rpms. The power to size ratio of motorcycles didn't really leave the impression this engine presumably would, as it wont spin nearly as fast.

If 226 g/kWh is the best BSFC that engine has to offer, then it's still not quite in the diesel efficiency range. The old 1.9 TDI had a best of about 195 g/kWh.

Anyone have a figure for an average sort of very good engine-maybe a Honda 4 cylinder, or the original Insight 3 cylinder??

Now these numbers 226 grams producing 1 KWHR- it is the best the motor does,right?
This must mean at full throttle, lowest pumping losses? Is it at the torque peak, or maybe at some lower RPM?

I'm guessing it is at some lower RPM than the torque peak, but maybe not. In the USA our engines are so big we rarely hit even the torque peak RPMS which is maybe 3500 for a V-8 and 4500 for a 6 cyl, and close to 5000 for many 4 cylinders.

In normal driving-level hy- with some city interstate onramps I'll hit maybe 2400 with the V-8 and roughly that-2800 maybe with the Prius.

Charlie

My 2.3L Honda Accord has 155hp... I can pull 41mpg (best tank). Imagine with that engine...

Since this is a Penske motor, will it go in the new Saturns?

Anyone who studies much thermodynamics understands that as compression ratios increase so does efficiency. However traditionally it hasn't been worth manufacturers to increase the compression ratio much because to do so requires increasing the size of the cylinders. This greatly increases the weight of the engine without increasing it's power output. So there's a fine balance for FE. There are other problems to face too such as gasoline's tendency to ignite unwanted under high pressures (knock).

My guess is that they use the third cylinder to do an initial pressurization of the air or fuel-air mixture, before it's put into the next cylinders and goes through what normally occurs in a gasoline engine. Perhaps they also do something similar with the exhaust and give it an additional expansion cycle to eek out a bit more efficiency.

I just wonder about how well it would run in an older car as:

"This is because at the onset of knock a greater percentage of work can be extracted in the LP cylinder"

So they're running it at higher pressures closer to causing knock, so it would seem that it would be much easier for the "balance" of the engine to come out of whack.

the numbers are impressive

So does this extra 'expansion chamber' just crank up the pressure? How is this different than a super-charger? Will this increase low rpm torque as well as hp?

There wasn't enough in the article for me to get a full understanding.

Hmmm. I honestly don't know what to make of this one. On the one hand I suppose that exhausting the high-pressure exhaust into an extra cylinder to extract more energy makes sense. (If I'm understanding this right, that low-pressure cylinder is driven on every crank revolution since it's shared by the two main cylinders. That's a slick setup.)

But...

I don't know how you do that without robbing all kinds of energy from the main piston for the sake of driving the low-pressure piston. It must rely on carefully chosen geometry and displacements. But if you want to increase the expansion ratio then why not just use a longer stroke, atkinsonize the valves and be done with it? Seems like a simpler path to the same destination.

600 cc 4 cylinder motorcycle motors-dead stock, not racing motors-make about 108 HP at the rear wheel which is maybe 130 hp at the crank.


That dead stock motor in a 600 cc sport bike is a racing motor. Sports bikes are race bikes and are marketed as such.

For comparison, the 1140 cc motor in my BMW motorcycle is 95 hp and is no slouch. But mine is a sport-touring bike, not a "sport bike," which is actually a race bike.

I wouldn't use a motor from a sport bike as a typical motorcycle motor, because it is not.

Harry

Earthling,

Tomato TOE MAH TOE

Earthling,

Tomato TOE MAH TOE

Maybe so but just how good of mpg does a sport bike get when taching above 12k? That's what would be required to get something as heavy as a car moving compared to that featherlight racing bike. In my mind the torque is way more important than hp when it comes to fuel economy. Motorcycle engines are all hp and very little torque. This will never work in something as heavy as a car.

Like I said, sport bikes get terrible FE in normal city riding(40 mpg at best in gentle city riding). I would say they are almost race bikes( a full on race motor would make even more power-like a Formula I non turbo engine).

I doubt that these bikes get better than 20 mpg when raced.

I figured it was a fair comparison because this motor was developed by a Formula I supplier, and it will certainly have to rev pretty high to get the peak power it gets.My point was it gets spectacular FE, but the HP isn't spectacular.

Getting that power with that FE is pretty good. I wonder what sort of economy a sport bike engine would get with simple tuning changes-less cam, smaller Throttle body or injector body.


There is a lot to be said for lower revs.Part of the reason TD do so well is the turbo charging allows then to make big engine power without the long strokes, higher piston speeds, increased piston and ring diameter, higher crank speeds which steal away power with extra friction.

Charlie
PS My only point-originally-was the HP wasn't exceptional. The FE apparently is.

Don't forget that Ilmore is partly owned by Roger Penske, a very savy guy indeed. He is also the U.S. importer for the Smart, and the owner of the Saturn spinoff. He may have greater plans in store than we give them for credit. Anyway it is a very interesting motor.

As I intrepreted the writeup, the expansion chamber is a low pressure cylinder which "captures" the "excess" pressure in the residual exhaust cycle. If this is correct, this would be truly new and innovative. But I agree, the article is somewhat skimpy on detail.

jimepting,

I'm pretty sure that old steam engines did something like this. They had a series of pistons capturing and reusing the lower pressure lower temperature steam. Of course my memory could be tricking me.

It will be hard to beat a TD even with the TD's wasting fuel to re-burn the particles trapped in their filters.I'm sure the diesel builders are diligently working on a better way.

Charlie