Classic Alfa Forums

For a few years I've heard of this engine that had oval pistons and wondered about it, but never had a look at what it was.
This morning I've remembered to have a look!
Now, I assumed that it would be as a normal circular piston but in and oval shape, but for what purpose.
The reality is far more odd!

https://global.honda/heritage/episodes/ ... ngine.html

A V4 500cc engine initially, later to a 750, revving well into the teens. But each piston looked like an oval racing track with straight sides rather than a pure oval, the manufacturing must have been incredibly difficult, how do you make a piston ring for instance? How do you bore the cylinders?
Each combustion chamber had 8 valves, 8! Madness.

Some of the strangest ideas I've read about...

They must have balanced and measured every part so very, very carefully to get those pistons to work at such high rpm.

Quite a success just to get it to run. Would also have been interesting to run a single cylinder one as a proper motorbike.

What Honda wanted to do was build a V8, but race regulations wouldn't allow it, hence the oval pistons. I wonder how much Honda spent on this project ?
John.

Nothing new here.

Our clapped out old Austin A35 had oval pistons!