i have a guy that is willing to build a turbo manifold for my t66. should i use 1 1/2 or 2 inch tubing for the runners? also what size should i use on the wastegate piping. would the 1 1/2 inch be sufficient enough to prevent creep? i want fast spooling to minimize the lag i will have with running a large turbo on the street. anyone have any direction on where i should go?

another question is should i use the .96 undivided that came with the turbo or should i use the 1.00 divided that i have on my present turbo and have the builder fab the manifold with the open or divided outlet? i am looking for 500rwhp at 19-20psi. whether or not i find it is up in the air b/c of the dilemmas i am facing.

to answer questions that i'm sure will be asked, currently i have a 60-1 with the infamous OBX "ebay special" manifold (that leaks like a stuck pig), an HKS 50mm racing wastegate w/a 1bar spring, and all the strong supporting hardware for a single on a large streetport.

please help and give good reason to back up statements. the machinist says that the 1.5 would be better for velocity, but i figured that is too small when running that amount of boost. what do you guys think?

 

i think you should cut out the guesswork and buy a reputable manifold....

Tube bends and placement are much more than guesswork

 

Use 2" all around and make the runners seperate, so you can take advantage of a divided housing. Start with a 1.00 housing and if you don't make the top end power you want then change to a 1.15 housing. Be sure to have the taps for the wastegate stay seperate for as long as possible.

Be sure to have it made out of SS 321 or a more exotic alloy.

 

Use 2 inch piping for sure

With the wastegate piping, put the exits into the wastegate on a bend of the pipe so the gas flows as directly as possible into the wastegate. Just dont make it a 90 degree bend into the wastegate otherwise you will have overboost problems!

 

Opps double post. Server got upset ...

 

2" ID is preferable and "flow" the WG pipes, closer to the turbine entry the better.

 

all right 2" it will be.

now, .96 open or 1.0 divided turbine housing?

 

I vote 1.0 divided. If anything, make the manifold divided and if you want you can try the undivided turbine housing but it's alot harder to go divided if your manifold builder makes it collected.

 

It's good to see Rice Racing again. Did you ever get a 3rd gen?