Clearance of exhaust pipe in lower cowl

[magiccarpet]

I have noticed that I need to make the cutout for the exhaust pipe in the lower cowl a bit larger. I am unsure what minimum clearance shall be achieved around the pipe to prevent damage from heat. I don't have the assembly instruction right here, but I can not recall that Van's specified a dimension there.
I target a clearance of 1/2". Is that enough?
Thank you !

 

[snopercod]

Are you worried about clearance for the heat or for the vibration?

 

[magiccarpet]

Are you worried about clearance for the heat or for the vibration?

I am more concerned about the heat. For vibration I think 1/2" around the pipe is more than enough.

 

[DHeal]

IMHO, 1/2" clearance is sufficient. However, you may find yourself increasing this clearance somewhat to facilitate installation and removal of the lower cowling.

 

[snopercod]

I have no special knowledge but went with 1" of clearance on my plane. Different airplane, I know, but here's what my cowling exit looks like. The "down turns" are for two reasons. 1: Noise. The straight pipes caused a racket in the cockpit, and 2. Now the exhaust doesn't leave residue on the bottom of my plane: