Exhaust to fuselage clearance?

I'm setting up my Vetterman exhaust on my RV9A. How much clearance should I try to get between the tail pipes and the bottom edge of the firewall?
Right now I've got a little over 1/2" and I suspect that might be too close.

Gnvflyer said:

I'm setting up my Vetterman exhaust on my RV9A. How much clearance should I try to get between the tail pipes and the bottom edge of the firewall?
Right now I've got a little over 1/2" and I suspect that might be too close.

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I have clearance of less than 1/2” with no issues. However, it may depend on how your exhaust is “hung”. I have suspension clamps very close to the exit opening - the mounting points act as a pivot during the start-up/shutdown shake and minimize the clearance needed. (RV-14A, Lyc 390, Vetterman exhaust)

Thanks!

KeithB said:

I have clearance of less than 1/2” with no issues. However, it may depend on how your exhaust is “hung”. I have suspension clamps very close to the exit opening - the mounting points act as a pivot during the start-up/shutdown shake and minimize the clearance needed. (RV-14A, Lyc 390, Vetterman exhaust)

View attachment 41563

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Thanks Keith!

I have the Vetterman exhaust with the mufflers (which add some width to the pipes). This is on an RV-9A with the old style nose gear leg (no rubber cushions). You should have plenty of room to get out of the lower cowl and clear the fuselage. The mounting system with the steel tubes and rubber hose segments gives a lot of flexibility in positioning, however I've broken two of the steel tubes and when that happened, the mufflers would sag enough to rub on the lower cowl. You can see in the photo how close the muffler is sitting just above the cowl. My engine mounts have definitely done some sagging over 1000 hours and 9 years, so it is even closer now.

New Nose Gear

I have the new nose gear on my 9A and the exhaust is very close to the cowl and the firewall. I even had to make special hangar brackets to mount everything near the nose gear. I did not worry abut how close to the firewall but I tired to spilt the difference between the cowl lip and the firewall. My problem comes up at the front where the pipes have the slight bend to go from the side cheeks to the lower " groove". You can search for my builders log here on VAF to see it all in detail.

YMMV

The real challenge is the heat muffs to the cowling in my opinion. Attachment of the Vetterman exhaust should be as close to the firewall as possible. I believe you said a 1/2 inch, that should be okay. Lower cowling should be attached for final fit...