"UltraJohn" wrote

Jim
What airplane POH tells you to run your reciprocating engine at max/wot
throttle?

Very few say that you can *not* run at WOT for extended periods of time.
You can choose to run WOT, if you want to, and stay at near sea level
altitudes, or if your engine is turbo-ed, or turbo normalized, and be
putting out max HP. With most certified engines and planes, there are no
immediate concerns.

Most small airplanes run max hp for about 10 to 30 minutes for takeoff and
climb then throttle back to 75% for cruise.

True, in most instances.

Most either throttle back to 75%, or climb to altitudes that result in the
engine putting out 75%.

So expecting a VW/corvair to go
max for hours on end and not break is unrealistic.

It is only not realistic, if the operator does not know what he can, and can
not, do. Saying , or implying that the Corvair and VW are equal, or close
to equal, I do not think is accurate. IMHO, the Corvair will do much better
at dealing with the higher output levels.

I personally think
either engine is viable in the proper application and treated properly.
One
of the first things in your testing phase is to make sure your not
overheating the thing.

It is a trick to see if you are overheating, with the typical VW or Corvair
instalation, since most have no way of monitoring CHT, or more specifically,
the valves, seats and guides.

It's quite well known a VW is not capable of
continuous operation at much more than 40 or 45 hp

Not well known (or admitted) by many people/companies.

(let's see 75% of 65 (65
being about the highest you'll want to run a VW) is 49 hp) so your
probably
only going to cruise at about 65% power which is not bad because you still
have that extra reserve for takeoff and go arounds!

Knowing and admitting that the VW will burn up their valves and
surroundings, if operated at much over 45 HP for very long, is a very "good
thing" on your part. g Still, I think most people think that they can run
a certified engine at maximum HP for extended periods of time, if they keep
the mixture full rich. The same can not be said about VW engines. I think
Corvair engines behave much like their certified brethern, with their regard
to being able to tolerate extended max HP runs, with a rich mixture.

I don't know what the max continuous of a corvair is but the same applies,
run it at the right level and you'll probably have a sweet little smooth
engine!

True of any engine. If you want to run at max HP often, for long time
periods, they will not run for as many hours before an overhaul. It simply
concerns me that some people believe that they can run VW's at 65 HP (and
some rate it at significantly more than that, without mentioning any names)
and only slightly shorten the engine life.

I just hope people know what they are getting, when they choose an engine.
You obviously do.

This is homebuilt/experimental right? ;-)

This isn't "on" anything. I was just talking generalities, about a VW
running at high RPM's achieving a long life before overhaul, and the fact
that high RPM's and high HP are far from the same thing.

I can't (and won't) argue against using VW and Corvair engines on airplanes.
It has been shown to work very well on many people's planes, when flown
within their limits. The only question is "what are their limits?" Most
people running them for any period of time (and still running them) know the
answer to this question, including some people on these groups. It is the
other people contemplating putting one on an airplane (with unrealistic
expectations) that I am worried about. g
--
Jim in NC

I hope I didn't step on any toes. That was not my intention. I am just
expressing an opinion, and you know how "opinions are like buttholes."
vbg