wrote

"Morgans" wrote:
wrote

Ooops, you attributed the following to me, and it was the OP.

just a good way to hedge your bets. say your're in the mountains,
it's stormy, and you have turbulence. no matter what Gs or static you
are subjected to, the engine would get a steady supply of oil, fuel
and electricity.

End OP quoted paragraph.

Morg: When have you heard of people being concerned at running a marine
auto engine at too high constant RPMs? Never. They run at RPMs that
would
worry me much more, and faster than most people run airplane conversions.
You can choose what drive ratio you want to run. A conversion running at
3,000 RPM is too fast for a prop, but not too fast to make me
uncomfortable.
I would not worry at running a conversion at 3,800 RPM for extended
periods
of time. I sure run my boat engine at higher RPMs than that.

Marine engines have a couple of advantages that aircraft
conversions do not: A ready supply of cold coolant, and a drive system
that doesn't apply and thrust or gyroscopic loads on the crank.

Yes, but a well designed and performing cooling system cools all the extra
heat an engine can produce. Don't you thinik the P-51 did ok with their
cooling system? There are homebuilt auto engines flying all over the place,
for over 2,000 hours that do not have a problem dealing with waste heat.
The ONLY time they have a problem is if they have to run sitting on the
ground, or too long of a taxi. Flying, they cool just fine, after they have
all of the bugs out of the cooling system. I will not say that some people
have problems, but there are hundreds of people flying car engines that have
absolutely NO problems with cooling in the air.

As far as the crank loads, that is taken care of with a PSRU. Another non
issue.

Running an auto engine at or near max power settings, like we do in
boats or airplanes, generates huge amounts of waste heat that autos
don't when they're cruising unless they're pulling heavy trailers, in
which case a trailer-towing package becomes necessary. This includes
much larger cooling capacity. Autos typically cruise at around 25-30%
power, boats and airplanes at 65-80%. I have experience with both
marine and aircraft liquid-cooled conversions, and believe me, the
boat is easy to keep cool.

And so are water cooled airplane engines, with good cooling systems, and it
is not that hard of an issue to deal with.
--
Jim in NC