Hi all.
Just about to fab a Y pipe from my shortie headers (unknown origin). I want to make 2 pipes to meet at the cat (long gone by the way), then join it to my 3" I pipe. Is a diameter of 2" enough from each header? What do you guys think? I'm scraping everything at the moment, so this needs tucking in well.

Thanks for any reply.
Andy.

 

well a 2" pipe will have 3.14 sq. inches of flow. Times by 2, you get 6.28. A single 3" pipe will have 7.07 sq. inches of flow. I think using 2" pipes will be a bit of a bottleneck. Maybe use 2-1/4" pipes?

 

Hi Andy,
two tubes 2.125" dia. have about the same area as one 3" tube.

 

2-1/4" would be much better.

 

You're right, but Andy said things were tight.

 

My hedman y-pipe uses 2.25" pipes off the headers and meets a 2.75" pipe where the cat is. It is tight, but even with the exhaust clamp inplace, it doesn't hit the oil pan. You should be alright. I wouldn' go smaller than 2.25", that seems to be pretty standard,

Will

 

Thanks for the reply guys.
Space is tight because of the SFC's and the constant scraping going over any bump.
I have just bought a pipe bender that goes to 2 and a 1/4" at a push. So I am going to try large first and see how it goes. I will post some pics as it is going along.
By the way, what coatings do you all use on the Y pipes. I don't want to ceramic coat at this stage, so what is successful? I don't want it to look like a rusty hulk in 12 months time

Thanks again.
Andy.

 

I have the same Y-pipe. Mine will be welded under the oil pan though, no clamp. I've seen this Y-pipe on other cars before, and it fits great. 2-1/4" pipe shouldn't have any clearance problems under the car/engine.

 

I was thnking about having mine welded in as well, once everything settles in and what not. I had a hell of a time installing it as space was tight in the garage and I had pushed the piece off the pass side header too far into the y-pipe and I have to pull it back out and hold it while I attempted to thread in some bolts. But it does puff just a little right there so I may have it welded yet.

Will