Ilmor announces 700cc five-stroke petrol turbo engine making 130bhp

From what I've read, and if I'm interpreting the info properly, two of the engines' cylinders operate in the usual 4-stroke fashion. The exhaust from these 2 cylinders are used to pressurize the 3rd cylinder, the "5th" stroke. I'm pretty certain that no actual combustion takes place within the 3rd cylinder. Also: Since the 3rd cylinder is being "powered" twice as often as the other 2, its camshaft needs to spin twice as fast, hence the smaller pulley. http://www.ilmor.co.uk/news_7.php Let us pray that they stick this thing in a true modern day Mini, not the overweight bloated version that BMW provides for us.

Thanks for the explanation and link. I wonder if the 3rd cylinder counts towards the engine capacity? If it does then those two cylinders are tiny! Just spotted the turbo is running at 3 bar!!

it's 4 strokes from 2 cylinders +1 stroke from the 3rd cylinder, powered by the exhaust of the other 2.

......and technology hasn't progressed between the "old muscle cars" and today...

Diesel fuel contains more energy than gasoline, so engines running on Diesel must be very sturdily built, i.e. heavy. To add weight would be contrary to what the engineers appear to be striving for with this particular engine...compactness, light weight (I'm guessing), and efficiency.

of course, the increase in weight should be proportionally on par with current diesels as compared to current gasoline engines... and by the same token should give the same proportionate advantage in fuel consumption (~25%) as heavier diesel engines do in comparison to lighter petrol burners. likewise, power/torque:volume should proportionally match, which doesn't seem to be an issue for diesel engines in cars like Smart with tiny size engine volumes. lighter engine weight for it's own sake hardly seems to be a prime objective (25% better efficiency also means the fuel tank can be sized that much smaller) ...anyhow, it'll be great to see the different forms it turns up in.