On Fri, 19 Oct 2007 11:05:32 +0000 (UTC), Bertie the Bunyip
wrote:

Matt Whiting wrote in
:

J.Kahn wrote:

It's not a problem when heating because the head expands faster than
the steel parts so the stress effects are reversed. This is why the
manufacturers have no problem with going from idle to full power as
soon as the engine will take it without stumbling. There is no such
thing as shock heating...

What about the aluminum piston in the steel cylinder?


That can happen too! But the clearances are cgrater ther than it would be
in a valve stem or head to cylinder seat.

If we had that kind of piston to cylinder clearance in an automotive
engine we'd think it was worn out. :-)) At least in the "old days".

Roger (K8RI)


Bertie