5 stroke engine

[callmedave]

interesting read, if a little brief:

http://www.ilmor.co.uk/concept_5-stroke_1.php


Callmedave

[nottyash]

Be interesting to see if it catches on.

[StottyZr]

website said:

ur objective with the 5-stroke engine is to develop a gasoline engine with fuel consumption and emission levels comparable to that of current diesel engines

Straight off the bat... What if you made one of these super efficient engines run on diesel?

[callmedave]

If you read it all, it mentions that it can achieve the MPG of a diesel engine without such harmfull toxins etc produced by diesel engines, i.e best of both worlds.


Callmedave

[Chris71]

Ilmor has been developing this for a couple of years at least. It'll be interesting to see what comes of it.

Coincidentally, double (or even triple) expansion was commonplace on steam engines.

[StottyZr]

doogz said:

StottyZr said:

website said:

ur objective with the 5-stroke engine is to develop a gasoline engine with fuel consumption and emission levels comparable to that of current diesel engines

Straight off the bat... What if you made one of these super efficient engines run on diesel?

You couldn't even manage to finish the sentence, no?

Its like my mind filters out what I don't care about

But to finish the sentence, following on my quote

website also said said:

...without the serious problem of particulate and NOx emissions that plague diesels.

[J4CKO]

Is this like they used to do with Steam Engines ?

Wonder if it sounds like Ivor the Engine in operation ?

[ewenm]

doogz said:

It's not really the same thing though. I must be misunderstanding, but the small piston is basically pushing the exhaust gas out, and pushing the large piston down. There's no 'free' energy to be had there.

Like I said, there's obviously something I'm not getting.

The exhaust gases from a 4-stroke have a certain amount of energy. This seems to be attempting to use that currently wasted energy to drive another piston (and presumably then exit the engine cooler than currently).

[callmedave]

ewenm said:

The exhaust gases from a 4-stroke have a certain amount of energy. This seems to be attempting to use that currently wasted energy to drive another piston (and presumably then exit the engine cooler than currently).

Yes looks like the high pressure from cylinders 1&3 are used to drive cylinder 2 (low pressure)

I assume its sort of catching the last bit of energy from the engine, or something like that, its interesting how the cams rotate at different speeds, it would be nice to see a CGI of one in motion. They mention they had a cut away one you could turn by hand, i would like to see that at Autosport or something.

I love this 'out the box' thinking, like the (canadian??) guy who built the engine that had extra cylinders in the head that worked like valves.

Callmedave

[Twincam16]

ewenm said:

doogz said:

It's not really the same thing though. I must be misunderstanding, but the small piston is basically pushing the exhaust gas out, and pushing the large piston down. There's no 'free' energy to be had there.

Like I said, there's obviously something I'm not getting.

The exhaust gases from a 4-stroke have a certain amount of energy. This seems to be attempting to use that currently wasted energy to drive another piston (and presumably then exit the engine cooler than currently).

Sounds almost like a turbocharger to me, only rather than firing the gases back into the combustion chambers, it's just passing them from one chamber to another onto a larger piston on a different stroke.

It'll be interesting to see how they balance the vibrations from this engine though. Would the emissions from the smaller pistons be regulated to ensure the same amount of combustable material enters the larger combustion chamber per stroke? Otherwise it could end up seriously lumpy at certain revs and temperatures.

[Mr2Mike]

doogz said:

It's not really the same thing though. I must be misunderstanding, but the small piston is basically pushing the exhaust gas out, and pushing the large piston down. There's no 'free' energy to be had there.

Like I said, there's obviously something I'm not getting.

It's exactly the same thing as a multi-expansion steam engine. The exhaust gasses from a conventional ICE are still expanding at the point they get pushed out of the cylinder on the exhaust stroke. By adding an extra expansion stage, you can extract some more energy from the exhaust gasses. Since the exhaust gasses now occupy a greater volume at lower pressure, the secondary stage has to be quite a lot larger in displacement.

I am certain the application of secondary expansion in a piston ICE is far from a new concept; I remember "inventing" this while I was at school and discovering that quite a bit of investigation work had already been made. It's really a pretty obvious thing to do, but clearly there will be packaging problems for higher cylinder counts.

[Mr2Mike]

Twincam16 said:

Sounds almost like a turbocharger to me, only rather than firing the gases back into the combustion chambers, it's just passing them from one chamber to another onto a larger piston on a different stroke.

A turbocharger uses exhaust energy to force more fuel and into into an engine to make it produce more power. Secondary expansion is extracting more energy from the exhaust which is directly contributing to crankshaft torque output with no extra air or fuel being consumed.

This effectively gives a larger expansion stroke compared to the compression stroke, which is the way that the Atkinson engine (.e.g Prius) achieves better fuel efficiency, albeit by a different method.

Edited by Mr2Mike on Tuesday 24th July 18:21