Hello

should tuned pipe be up against header or should there be some space between, if so how much?

Anyone know if Macs in closed, not answering the phone the last two day's.

thanks for the help
Frank

There is usually about 1/8 inclearance between the pipe and header to prevent metal to metal contact. A larger gap usually causes the connector to blow out.

The distance between the header and the pipe - handled with silicone tubing - can be very useful for fine tuning the tuned pipe length. I've never had a problem with a 2" 'gap' that exists after fine tuning with each end secured with nylon cable ties. After all, the header is secured to the engine and the pipe is secured to the airframe, right? With this sort of arrangement I don't see how a 'blow out' can occur, unless you have a very short overlap of the silicone tubing on either end.

I suspect that in the past not all silicone couplers were equal, i.e., some had rather low melting temperatures and would fail if sufficiently heated without a piece of aluminum in between the coupler and the hot exhaust gasses. I've seen them burn through. Whether the size of the gap made much of a difference is debatable, but it makes sense that aluminum blocking a large section of coupler from contact with the exhaust gasses may give the heat a chance to travel down the aluminum and radiate into space.

Ed Cregger

When tuning the pipe, you usually shorten the header 1/4" at a time until the engine speed stays the same or drops slightly, then pull the pipe out of the coupler a little to recover the RPM. I've run pipes with up to 1/2" "gap" with no problems. Use nice large wire ties pulled really tightly to secure the coupler and you'll have no problems. Use a pipe mount at the middle or rear of the pipe to secure it to the fuselage.

Dr.1

Thanks for all the help guy's

Frank