AAZ or any downpipe measurements question. ID or OD

[gribur]

When you guys are talking about having a 2.5" downpipe or a 3" downpipe is this referring to the OD or ID?  What is the standard used by companies who make these?
cheers

[Thezorn]

There is only one company Ive ever seen that makes then, and even then they have to custom build them for you I think, Techtonic tuning.
Im sure they could make them any size you need. The other best thing to do is make your own with a couple mandrel bends and a peice of flex pipe.

SmokeyEddie has pics of his in his build thread.

[theman53]

99% sure my 3" is ID of the pipe.

[Thezorn]

Oh yea forgot about that part of the question. Alot of companies are different as to wether they rate there pipe in ID or OD all of the exhaust I have is in OD.

[gribur]

just wondering, i got an email from techtonic and they said that their 2.5 was the OD, i for sure would have assumed that you were buying a 2.5 for the inside diameter, shows how much i know LOL.  I will never learn it all, gotta love it.

[mystery3]

Makes sense as 99% of pipe/tubing applications in the world measure ID, otherwise wall thickness has a greater impact on flow than does diameter.

[truckinwagen]

tubing is measured in OD, pipe is measured in ID

exhaust is made out of tubing, thus, it is OD.

the wall thickness of the tubing used is usually thin enough to make little difference in flow.

-Owen

[theman53]

quote from summit racing
Ex.Manufacturers usually measure ex. tubing by the OD and the slip fit connectors by the ID. That way a 3" muffler will fit over a 3" tubing.

Who uses mufflers anyway