In addition to RPM and Boost factors, compression ratio also comes into
play.  Higher compression ratios = higher power (and efficiency) but also
lead to detonation if you can't keep the cylinder/head/piston cool enough.
Liquid cooling can provide added cooling capability at the cost of
weight/complexity and typically radiator drag.

The Trace/Orenda web pic's don't show any radiators.  I'd be very interested
in seeing those.

p.s. I've often wondered why someone hasn't designed/built an air cooled
cylinder head with added oil jackets/galleys in the heads to provide added
liquid cooling capability via oil (with an enlarged oil cooler as
necessary).  The oil cooling may not be ideal, but would seem to be a
compromise between air and water/ethyleneglycol with minimal added
complexity - especially if it were just used to augment air cooling at the
hottest locations (e.g. around the exhaust values, etc).


-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Rob
Logan

hmm, I'm confused, this is 495 cubic inches..
the TSIO-550 is bigger so it can pump more air,
so with a stoichiometric mixture one would
be burning more fuel... and isn't that faster?