The pipe I made was 88 MM or just a hair under 3.5 inches. I believe that is ok for a Titan, but the Merlin is moving a lot of hot air so to speak. A single wall pipe wrapped in aluminum wrapped in ceramic blanket was getting so hot at the inlet of the pipe that the pipe heated the resin out of my fiberglass by pass where the pipe meets the bypass.

A couple of lessons I learned

1) I had the engine moved as far forward as possible in the engine compartment to get CG requirements in check. This meant my pipe inlet had to follow the engine to get proper clearance between tailcone and pipe. When I did that, I brought the pipe about two inches inside the bypass. This cause another suspected problem in that there may not have been enough cooling air from the inlets through the by pass and into the pipe to mix with the hot air coming out the engine. While my EGT never hit 600, my pipe inlet went well above that.

So I chopped off some of the pipe and was working towards moving the bypass more forward to make up, but long term I just decided I was chasing problems rather than just buying a correct solution. A couple more hundred bucks for the right stuff will go a long way.

2) That aluminum hvac tape.......... The aluminum is good to some pretty high temperatures. The adhesive is not

3) The only guys I know that can make a single wall pipe work are a NASA rocket scientist and a polar opposite trash talking cajun weatherman. I need to stick with commercial solutions for now as I burned up all four pipes I made (burned up in the sense they turned blue and I don't trust blue pipes as a rule).

The P-200 Isobar that flew last weekend didn't even turn their dual wall pipe bronze. That's a solution I can live with.

Anyway, once I get that stuff, I'll post here as it comes together.