Check out the Revetec engine!

[cygnusx1]

Similar to a radial layout but looks like it would be extremely strong and efficient. This looks like it's production ready. The X-4 from down under. Rotary meets pistons.

 

http://www.revetec.com/

 

http://gas2.org/2008/06/26/low-cost-gas-engine-innovation-doubles-fuel-economy/comment-page-6/

 

 

I want to be the first to suggest a turbo with 30psi boost! It looks plenty tough enough to take it.

 

 

This was back in 2006....http://forums.hybridz.org/showthread.php?t=111578 seems like a lot of work has been done since then.

[blue72]

I hadn't seen this one before, interesting premise.

I was thinking it might have something more exotic than two pushrod actuated valves per cylinder. They are probably less expensive to produce, but maybe they'll come up with a 4 valve design in the future. I also would have thought it would be noisier at idle with all of those straight cut gears, but it didn't seem too bad. Certainly sounds like an old rotary piston engine from an airplane in those dyno videos.

[cygnusx1]

I think they did render a Twin overhead cam version but it adds a ton more parts. I think their primary focus is on getting high efficiency with low parasitic losses to get gov't backing or funding. I can see this engine becoming very efficient but also being able to be produced with a focus on high torque and power to weight ratios. Great for small planes....and hotrods.

 

Notice they did show a version with counter-rotating lobes which load both sides of the "control arm cam followers" front to back, evenly, to eliminate the bending moment in the arms. This, in my eyes, makes this a VERY stout motor. The pistons also won't rock in the bore very much if at all, increasing the longevity of the pistons and bores. The weak point is that due to the offset of the front to back lobes, there is a twist force induced on the "connecting rods" These connecting rods will need to be very stiff in the twist axis. I can even see this motor easily becoming a diesel.