David Leonard wrote:
Ed, don't forget that the Powersport's engine is putting out a few more horses - necessarily creating
more heat. I would be very surprised if Keith and the Powersport crew never bothered to properly
tune and map their engine.
Lets face it, Powersport is doing a better job than most of us. They make a first class installation
and its only the first class price that has kept many of us away. Of course, everyone does something
different from the way `I' would do it. In retrospect they see that they would have done some things
differently, but won't we all? I am very sorry to see this happen. The negative publicity is
unfortunate and undeserved.
Paul Lamar responded:
Dave, EGT's are the same regardless of the HP. If what you say were true radial engines would melt
exhaust valves in seconds.
IMHO they need more negative publicity not less :) Most stubborn, closed minded and not invented here
people I can think of right at the moment:)
Good grief, Paul! Who pissed in your Post Toasties(tm) this morning? Bad for your karma to wish bad
things on another.
And BTW, I think David's premise has some merit: for the same displacement, EGT goes as HP goes. This
is because the engine's efficiency at extracting useful work is somewhat fixed (percentage-wise). As
the amount of useful work extracted goes up, the amount of waste heat also goes up. But the exhaust
system's ability to shed that waste heat is somewhat fixed (as delta T goes up it gets better, but not
as fast as the delta T is increasing). Thus, burned exhaust valves, burned exhaust manifolds, burned
mufflers, ...
Your "melting radial exhaust valves" is a red herring because the radial engines have a larger
displacement than the usual 4 or 6 banger. I'd speculate that the radial engine's HP per cubic inch is
in the vicinity of the O-360's HP per cubic inch.
Russell Kent
Power Sport needs a wake up call. I have been talking to them for years
about certain things. I suggested they sell engine parts instead of
complete fire wall forward packages to jump start the market
five years ago. They ignored me. The slow growth of the market for rotary
powered airplanes proves I was right. Only now are we seeing
off the shelf motor mounts and intake manifold parts.
We still have a ways to go on exhaust systems and other needed
parts. Ironically their firewall forward business would be way
head of where it is now.
We had a huge go around in private about
bad mouthing planetary gear boxes. On their web site and on here.
I refused to publish their bad mouthing planetaries on here.
Their overly heavy and too expensive spur gear box was the only
way to go according to them. Tens of thousands of hours behind
rotary engines has proven the light weight Ford planetary
can do the job.
As you pointed out it is bad for your karma and bad for your business
to bad mouth your competitors. I don't give a damn as I am not
in this to make money.
They refuse to move the rad on their RV6 after years of inadequate
cooling. "By God the best place for the rad is in front of the
firewall and we will make it work come hell or high water."
I am paraphrasing of course. The exposure they get on this feature
in Sport Aviation, Kitplanes and the web somehow legitimizes
the location and is a trap for new people starting
out installing the rotary. I offered my hangar space, living
quarters and machine shop free if they wanted to do some cooling
development in a hotter climate than Minneapolis in the winter
time. The offer was greeted with silence.
They never show up with the airplane at Sun & Fun, Arlington
or Copper State. To fly that far and to those locations would
be a real test of the cooling system.
They no longer enter the Sun 100 cross country race as
Everett Hatch and Allan Tolle did religiously. This slowed
the acceptance of the rotary to a crawl. Allan Tolle went
238 MPH and had the fastest time to climb five years ago!
Where would we be today if Everett was still alive?
They continue to put the fuel injection on the hot side
of the engine. We have had four in flight fires and one fatality
mostly due to this feature. All well publicized on this news letter.
Some as long ago as three years.
I have no doubt they ignored the data provided by Tracy and others
on the mapping of the fuel injection computer showing that the
exhaust temps came way down when you leaned the rotary engine
a couple of hundred degrees lean of peak during cruise. The same
as a piston engine but unlike a piston engine the rotary will
run fine at 200 degrees lean of peak.
I will say one thing. They abandoned the oil to water heat
exchanger.
Now as to yours and Dave's education on EGTs. The P&W R2800 was 2800
HP. That is one HP per cubic inch. The Lycoming O-360 is
180 HP or .5 HP per cubic inch. The EGT's are the same.
The same goes for the RR Merlin. Late versions of which were
well over one HP per cubic inch. The EGT's were the same.
The rotary engine is the exception to the rule as a higher percentage
of the total heat is wasted in the exhaust. You and Dave are
confusing the TEMPERATURE of the waste heat with the QUANTITY
of waste heat.
Paul Lamar
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