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Would stress really go up? Sure you have a large lever arm when the piston rolls over the nose of the cam and starts pushing it down, but it seems that there is a large bearing area available. In a standard IC engine all that force is transmitted through a half inch wrist pin and a two inch rod journal.

I just spoke with another engineer here and apparently Revetec has been hawking this engine for a couple of years without any real bites. Cool tech, high power density, but expensive.

On another note, I'll bet things could get interesting in a hurry if one of these engines develops a misfire.

You not only have the stress from one piston, you also have to add the stress from the opposite one as well. In effect, those lobes take both the stress from combustion as well as the stress from compression plus rotating mass forces. Depending on the angle of the lobe, there is shear force as well on the bearing assembly. A roller bearing may keep the cam from wearing too fast, but the load is always on one side of that bearing. It would be debatable over which bearing is better, I think a bushing would be better as far as tolerances go, as long as it has some decent oil pressure going through it.

Id say you'd need some very hard surfacing to keep it going for any length of time, and that's the slower moving parts. What about the valve train? On a 3 lobed engine, that cam has to turn 3 times for each one revolution. At 2000 rpm, that cam is doing the work of a regular engine running at 6, which floats the valves on a conventional engine.

I haven't looked at what cam system they use, either 1, 2 or 4, but that's a lot of cam to turn. Even if say, that engine maxed out at 3,000 rpm shaft speed, that valve train would run at a punishing 9,000 rpm. If you've ever built a weekend race engine, it takes some doing to keep the valve train together at those speeds, plus expense, and it doesn't last long. The lobe problem may be overcome with some good metallurgy, but I doubt that the valve train issues can be. Not for a commuter car application at least. With 4 overhead cams, it would run pretty good for a while no doubt. It would be a train wreck if something let go through.

I don't know what the limits are for fuel injectors either, but I can't see them being of any practical use at the potential high rates needed. At say 12,000 firings per min, You may as well use a blower and carb and try to burn as much fuel as you can as it flows through the cylinder, LoL

I think they are counting on this engines torque and lower crank speeds than what I'm thinking of. Maybe in the 1000-1500 speed range max.