drive-by-wire

[Hans Hintermaier]

> On Sat, 5 Oct 1996, Daniel Ridge wrote:
> > 
> > PS: we were talking a while ago about non-circular pistons.
> > Wouldn't non-circular piston rings be difficult?
> 
> yes, very difficult. Honda tried it one of thier racing motorcycle
> engines. They used oval-shaped pistons.

At last the engine standed nearly one whole race, but oil was empty...
They ran like hell, surrounded by a blue cloud.

VW built some test diesel engines with elliptic (not oval) shape. Not for 
putting eight valves in one head as Honda did, but for making a given 
4cyl engine not longer with more displacement.Because the elliptic 
shaped piston has no parallel sides, it worked fine. The rings had 
pressure constant all around. 
BMW made (no successful) experiments somewhen in the seventies with 
octagonal ceramic pistons. I don't know why they used that shape and 
how they machined the rings. Ceramic was not far enough in those times and the
pistons cracked when temperature changed rapidly.

Hans
hiha@ brain.nefo.med.uni-muenchen.de
Munich / Germany