5 stroke engine could increase FE by 5%-20%

[Piwoslaw]

Ilmor Engineering shows off 5 stroke engine concept
I wonder if this idea has any chances, or will it end up in the bottom of a drawer by this time next year?

[micondie]

Ilmor is a major player in the racing field where the goal is to maximize output from a specific displacement motor. (Efficiency!!!) They know motors and I don't think they would risk their reputation without some real science to back them up.

[darcane]

This kind of reminds me of Bruce Crower's (of Crower Cams) six stroke engine:
Inside Bruce Crower’s Six-Stroke Engine: AutoWeekMagazine

Getting an additional power stroke from the fuel that's already burned seems like a logical extension of the standard ICE.

Mike

[darcane]

Originally Posted by micondie

Ilmor is a major player in the racing field where the goal is to maximize output from a specific displacement motor. (Efficiency!!!) They know motors and I don't think they would risk their reputation without some real science to back them up.

I'm curious how they calculate their displacement. Is the third cylinder for the low pressure expansion considered swept volume or not? I imagine that there is significantly less power harnessed from that stroke compared to the two normal cylinders.

Mike

[gone-ot]

...150 hp per liter?!? How much for a gallon (wink,wink)?

[RobertSmalls]

This is a nifty exhaust waste-heat recovery scheme. The third cylinder is a heat engine that happens to share a crankshaft with the other two. You could do something similar with a divorced cylinder whose intake valve is attached to your exhaust. The fact that it isn't already done by long haul trucks tells me that the amount of energy recovered is too small to justify the cost and complexity of the system. I hope it works out and we see this technology in everyday cars, but "claims that efficiency gains of between 5% and 20% can be had" is a far cry from "have demonstrated efficiency gains of 5-20%".

[aerohead]

Is the 5-stroke the same as the 5-stroke Miller-Cycle engine already in production with Infinity cars?

[RobertSmalls]

No, the Miller/Atkinson cycle is just a delayed intake valve closing, allowing the compression ratio to be less than the expansion ratio. The novelty here is all after the exhaust valves. The two are not mutually exclusive.

[Bicycle Bob]

This is so much like a double-expansion steam engine I'm surprised to see it arrive so late. It could certainly work. The old Napier aero engines wound up with fabulous efficiency by making the exhaust turbo work hard.

[bgd73]

insanity.