Ilmor Engineering, the firm made famous for its work with Indy Cars and Formula One, as well as Triumph Motorcycles and Harley Davidson plus GM, Honda and Mercedes have built an engine that will make you think for a bit, it’s a 700cc, 3 cylinder, 130 horsepower turbocharged 5 stroke. Did they say 5 stroke?
The 2 outboard cylinders are the high pressure (HP) fired cylinders while the center low pressure (LP) cylinder makes extra use of the exhaust gases. The point of this design is to enable the expansion and compression strokes to be decoupled. The effective expansion ratio is 14.5:1, almost diesel territory, converting the maximum thermal energy into work. The compression ratio can be reduced, delaying knock, without a decrease in performance. The extra expansion stroke of the LP cylinder is, effectively, the 5th stroke.
Fuel consumption and emissions levels are similar to that of current diesel engines, without the serious problem of particulate and NOx emissions which plague diesels.
Fuel consumption is decreased by 10% over conventional 4 stroke operation. The entire engine is built using conventional technology, no new manufacturing technology or processes are needed.
This is more than a computer model, the running prototype is being dyno tested with a second development engine planned for in-vehicle testing.
Just when you think the internal combustion engine has pretty well emptied the bag of tricks, a little creative thinking comes along and gets higher fuel efficiency and lower weight than equivalent engines by adding another stroke to the process. So now we have 2, 4, 5 and even 6 strokes. Very impressive engineering, I like it.
Link: Ilmor Engineering
More images below:
Dan Martin says
My 1969 BSA Rocket III 750 could not even dream of such technology. But I CAN tell y’all this: the old Beezer RIII had the best sounding exhaust of ANY of the bikes I’ve owned. See them here: http://www.dansher.com/mywheels.htm
Being there are only two fired cylinders on the new 5-stroke, I bet it sounds like some kind of asthmatic Harley steamer… BANG – whoosha – whoosha – BANG (repeat)
or would it be more like BANG – whoosha – BANG – whoosha …
Either way: UGH
Walt says
While the dreamers hallucinate about hydrogen-powered vehicles (which would require a vast industrial complex to make possible) these guys do it with their brains. Fabulous.
As to sound, Dan . . . most engines are muffled well enough that their characteristic sound doesn’t matter. And for cars and trucks, here’s my idea: use the power of the vehicle’s sound system to create the audible image you want. Use noise-canceling technology to make it silent, or synch with road speed and program the system to imitate a Rocket III, a Ferrari v12, a Ford Flathead or a P51 Mustang. You choose.
Just don’t make it sound like one of those hopped up diesel pickups. That diesel blatt to my ears is not easy listening.
nortley says
There’s the ghost of an old marine engineer at Ilmor. This is nothing less than an internal combustion version of a compound steam engine. In steam form it gave sufficiently increased efficiency over the simple steam engine to allow sails to be left off of ships for the first time ever. That’s quite an act to follow, but any real increase in engine efficiency is still a gain.
David says
I’ll take one and build a motorcycle around it
HowardsCustoms says
A few people are revisiting this concept. It is not new and has existed, at least in theory, for quite some time. There was a *large* stumbling block related to this type of engine, but I can’t recall it off the top of my head. Anyway, the article I saw recently from another company doing the same thing said they addressed the issue in large. I think it may be heat related. Sounds promising!
kim says
What’s this thing about ‘just when you think the internal combustion engine has pretty well emptied the bag of tricks’? That kind of thinking disappeared about the time the Wankel engine turned out to be a niche product instead of the savior. The ICE has loads of development potential – all ceramic materials so it doesn’t need liquid cooling, to mention but one thing.
As intriguing as 700 cc and 130 bhp sounds, it doesn’t help the underlying problem, which is our collective power addiction. At one time in history the 23 bhp of an Indian Scout or the 50 bhp of a large British twin was considered plenty, but like junkies we crave more and more for our next fix. Then of course not many reading this blog will classify that as a ‘problem’.
Jon says
Kim, the power addicition of few shouldn’t really be considered a problem.
Most people who want high efficiency and cleanliness want that for themselves and don’t mind if some others have gas-sucking race bikes.
Given that at 700cc, this engine gets around 185hp per liter, consider how much power a 200cc version would get(!). I’m no expert, but I suspect 200cc will still yield good fuel mileage and relatively excellent performance.
Sadly, this type of technology has to succeed in the big, high-margin bikes in order to work its way down to the small, efficient commuter bikes.
todd says
“lighter” compared to a diesel. This is cool but I think there is more potential in the 2-stroke model.
-todd
David says
Dan Martin –
I just wanted to thank you for the pleasurable 2 hours I just spent on your websites, motoring and musical. The rush of my own memories that your pictures awakened has been both pleasant and melancholy.
WillyP says
The displacement is irrelevant, what really counts is power to weight, power to overall volume, and usable power, ie, ‘power under the curve’.
Laurent says
Very nice work,
I totally agree that the ICE still has plenty of potential and a lot of work is being done to revive some concepts that required advanced materials or manufacturing process difficult to achieve in the past, not to mention novel and original ideas (many showed here)
Personally, I think it is more than time to go back to the original diversity, we’ll have many many fuel sources and it’s more than time we use them.
As far as power junkies, it’s just a matter or efficiency (displacement/output) the more, the better 😉
Best
Paulinator says
I love this stuff…but why is this better than a Miller-cycled engine? I see more piston ring friction and plumbing losses here. Also, there are overlapping dwell issues between the HP piston BDC and the LP piston TDC that will stop the exhaust flow in its tracks – and that’s got to kill efficiency.
I’m with Todd on this one.
LADucSP says
Excellent engineering and beautiful construction are hallmarks of Ilmor, and this is no exception.
Buuuut, a 10% reduction in fuel consumption? That’s insignificant and far exceeded by hybrids, and easily equaled or exceeded by simply reducing weight and complexity of the vehicle.
Heck, VW’s got a 170mpg car coming to market within 3 years (fingers crossed). Regardless, it demonstrates the potential of innovative deployment of existing technology. VW’s solution is a diesel hybrid, coupled with extreme light weight through composites and aerodynamic efficiency.
So, although technically interesting and beautifully crafted, IMO the Ilmor 5 stoke will ultimately be a mere novelty on the way to the powerplants of the future.
Paulinator says
I just noticed that the bores aren’t in-line. That trickery probably resolves that piston timing issue – and raises a few others in the process. 10 percent? Hmm?
Zak says
I start to wonder… What would happen if you injected a *TINY* amount of water into the LP cylinder while the hot exhaust was still expanding? More power + faster spooling turbo?
Stellan says
How much does it weight? I want one!!
woolyhead says
Not bad……not bad at all. IMHO there is no “best” engine/motor….or never will be if mankind requires fur\ture mobility. I’ve always said the most fun is on a small bike….how about a 15 hp streamliner (3 wheels) ?
Jac says
It would be interesting to contrast the performance and efficiency of the Ilmor 5 stroke against the Fiat Multi-Air. The Fiat can do much of the same thing actively changing the cam profile on the fly. Both claim similar fuel economy improvements.
Nice to see fresh thinking.
Bob Nedoma says
@Dan M. The sound you will hear is the exhaust pop of the third cylinder, “the fifth stroke” once every revolution. No asthma.
While the idea sounds quite brilliant, one question begs to be answered:
The crank angle and valve timing of the third cylinder. 180* crank, offset by a few degrees in the block can’t possibly be the best solution.
Ivan says
Interesting, but not new. The 1906 Compound built in Connecticut USA used a similar system. Was said to run very quietly with a very cool exhaust. 16 horsepower.