[Brian Thomas]

McCulloch built a square piston motor, just to see if it could be done.

[Alan-Lidke]

I remember (I think) Honda had a bike engine with an oval shaped piston. Had 2 rods/piston if I remember correctly. That was quite a few years back tho.

[mike clements]

Alan, I read about that Honda engine also. It was an experiment to see if they could flow the same amount of air with a V Twin as they do with a V-4.   So, they used 2 BIG oval shaped pistons with 2 rods per piston and 8 valves over each piston.  I could see where the thing would Fly if they ever got the rings to seal.

The Scotch Yoke type crank I used is the main draw back to making HP with this little motor.

[Jim Russell, Jr]

Honda has built experimental engines with square and rectangle pistons. The Oval piston engine was a production engine in a motorcycle. Anyone could purchase one with enough $$$ as it was a race homologation special. It was a V-4 engine designed within the rules that did not allow 8 cylinder engines.

[mike clements]

James, I couldn’t remember if it was 4 or 8. But I did remember it was intended to make 1 cylinder move as much air as 2 cylinders. I did not know it ever made it to production for public consumption. I would love to see whatever they used for piston rings though.
thanks,
MC

[Jim Russell, Jr]

Soichiro Honda first created a piston ring company. Then developed into motorcycles, cars, and all sorts of combustion engines.

He focused on R&D so lots of radical ideas were implemented and tested in real world settings.

Did a little research. First Honda using oval pistons was 1979 NR500 GP motorcycle. Production for public sale was 1992 with 90 degree V-4 750cc for a paltry $50k. <!–nextpage–>

[Walt Gifford]

Looks like a good torpedo motor.

[Colm O’Higgins]

Weird history, but valid.

[mike clements]

The weak link in my square engine is no doubt that scotch yoke crank unit. I just don’t see how I can ever make any rpm with it.

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