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Rusty, good point about treating your exhaust
kindly - that is about the only valid reason for "cooling the EGT". I
think we agree it is not an issue of engine "running badly" or "hurting engine"
- just hurting the [non-Inconel or non-titanium] exhaust pipes.
It always happens - I make a dogmatic statement -
and get to learn something I hadn't thought of before!
I'm thinking if mine were to run that hot, I'd just
back off the throttle (or lean aggressively) to cool the EGT to whatever I
thought the exh system would tolerate ddurig climb (or race) - but wouldn't
change a thing about the engine, timing etc. Hmmm - I wonder about
timing.
Once I built up a VW engine for use in an airplane
- put it back in my VW Bus and cranked it up for first time - exhaust smoked and
eventually the "undercoating" (petroleum based) that I'd sprayed under car to
protecte from salt and snow in Des Moines, Iowa, caught fire!! I hadn't
thought the engine was running quite right - then it dawned on me: The
timing was way RETARDED - firing too late - and lots of stuff burning at flame
temp IN THE MUFFLER (a Kadron extractor). That's why it was so hot.
When I rechecked the timing and got it set correctly, the "high EGTs" went away
- no more smoking and fires back there. Ran it another eighty thousand
miles in the bus (didn't build the Vari-Eze).
So, could "timing being retarded/firing too late"
cause "higher than normal EGT"? Anyone else think there might be a timing
problem if someone reports "higher than other folks' EGT"? Not making a
"dogmatic statement" this time, just asking for a sanity check or other
operational anecdotes.
David
----- Original Message -----
Sent: Wednesday, May 04, 2005 9:47 AM
Subject: [FlyRotary] Re: EGT temps
So, I believe there is no such thing as "EGT too
high". There is only "peak EGT", whatever it is for your
installation.
Hi
David,
Everything
you said sounds right to me, with a note that the (NA) rotary can run way lean
of peak, and not be damaged. This is actually a neat phenomenon. You
can climb to cruise altitude, and leave the throttle wide open, then use the
mixture almost as a throttle.
I would also
have to note that EGT can be too high. Mine will easily exceed 1800
degrees, and I don't think I'd want to do that to my exhaust system very
long.
Cheers,
Rusty
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