Chris,
I too had an exhaust/intake system that wouldn’t fit under
the stock cowl. I hacked holes and had “speed bulges” for about
two years (before I changed the intake and exhaust).
I had very little clearance (only ½”) but never had
a problem. I had some reflective tape (insulating tape?) on the cowl, and
two years later, when I pulled the tape off, there wasn’t even any
discoloration of the fiberglass.
That said, the plane wasn’t painted at the time and I don’t
know what might have happened to paint.
Matt
Subject: [LML] Clearance
between exhaust and governor boss and cowling..
I
am fitting the cowling around an IO-360-M1A/B on a 320 airframe. This
engine has a wide sump and inlet pipes that are too close together to allow the
exhaust pipes to pass in between. The result is a larger cross section that
doesn't fit inside the standard cowling/scoop combination. I have cut slots in
the cowling/scoop to accommodate the exhaust, and will need to modify the
cowling clear it.
First
question is how much clearance to leave between the exhaust and the cowling,
and what recommendations do you have for heat shields at the critical locations.
The advice I have received so far is quite variable, so I don't expect a
consensus, but any views would be appreciated.