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For what its worth, Greg, I turbocharged a couple of
Honda Civics back in the mid 1970s.
The exhaust was made out of mild steel and I did wrap one set
of headers with heat shield tape. The tubes did not last three
months before one sprung a small leak, it was on the underside so I did
not catch it. I had fortunately installed an oil pressure gauge because
half way through a 600 mile trip I happened to notice the oil pressure headed
downward.
It turns out the exhaust leak was impinging on a
stainless steel braided line used to return the oil from turbo to oil
plan. The heat had charred the rubber liner of the hose and oil was
rapidly leaking out the stainless steel line - if it had been under pressure and
oil had sprayed on the hot turbo/exhaust pipes, my first indication might have
been a fire under the hood.
There are other methods of shielding things from the radiant
heat (positioning, coatings, SS sheets, Thermofax, etc) that do not incur the
risk of "hiding" your exhaust tubing with tapes/wrap. In a car, where you can
shut off the engine and pull off the road - it might be an acceptable risk to
some, but I just do not think any sort of exhaust wrap belongs in an
aircraft. It might work just fine - but, if it does not........., ..but,
just my opinion.
Ed
----- Original Message -----
Sent: Wednesday, March 05, 2008 2:21
AM
Subject: [FlyRotary] Re: Exhaust? was
[FlyRotary] engine installation pictures
No answers to any of these questions Bill. I will call
Brian tomorrow and see what's up, and get some specifics. He brought it
up because we have been talking about the turbocharging issue, and how/where
to locate all of the parts, including shielding.
Greg
----- Original Message -----
Sent: Tuesday, March 04, 2008 10:57
PM
Subject: [FlyRotary] Re: Exhaust? was
[FlyRotary] engine installation pictures
Yeah, and my friend in SoCal, the Racer again, says
that the 20B racers down there wrap, and it really helps. But then
again, racers......
Greg
Greg,
And they tested this how? With what instrumentation? So you know I have
built racing cars and bikes for others and I have road raced motorcycles
myself. The only coating or wrap I could find that worked was the Jet-Hot
coating. That was on a motorcycle. The in cowl temps were reduced by 15°F.
There wasn't any HP increase that I could determine reliably. I did record
an increase on the wheel dyno but not enough to be certain it wasn't just
different temp and baro pressure conditions. The rotary exhaust temperature
is so much hotter that Jet-Hot has only had a suitable coating for about a
year and a half. I'd try that if you must. Shielding, even thin and close
has proven to be effective, as has zirconia ceramic blanket. The wrap may
not have actually caused the cracking on the exhaust system mentioned
previously but it certainly makes it impossible to detect cracks before they
get dangerous. I'd stay away from wraps for just that reason.
Bill Jepson
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