What's up guys. I'm getting close to having everything for my turbo setup. I've decided to run a low/rear mount setup for ease of installation. I will run a 2.5/2.5 - 3.0 Y pipe that will be the merge basically.

My question is what size pipe do I need to use to fit it the turbo flange. Flange is a T4 open flange.

Also where's the best place to buy my j-bends and straight pipes? Needs to all be stainless.

 

No help?

 

I am pretty sure columbia river sells a pipe that is pre formed to fit the t4 flange. I purchased there t6 preformed pipe. I know mine was a 3" pipe.

 

Tube Bending & Fabrication - Columbia River Mandrel Bending all you need here.

 

Columbia River has always taken forever to ship/get parts to me. I used Ace Stainless for this last project and I was super happy with shipping time and the quality of everything.
Check out page 3 of my build thread for info on what I ordered and what not: https://www.performancetrucks.net/fo...-build-509803/

If your T4 flange is the oval/rectangle one you can make a 2.75" pipe fit, but a 3" will fit perfectly.

 

Thanks guys. I don't wanna limit the turbo anymore than I already am so ill use a 3" pipe for sure. I thought of marking out where the pipe would fit to the flange and then porting it on one side to fit the pipe. Any thoughts on doin this?

 

You dont need 3" unless you have 600+ cubes.....friend of mine did a test with a 106mm turbo and a 450" engine, did tests with 2" up to 3" pipe and only made about 15 more hp (on a 2500hp setup), but moved the powerband up and increased lag drasticly. Basically, 2.5 is fine.

 

Do you mean for the crossover or the merge?

 

On my build I ordered from Columbia river and Ace stainless both shipped about the same time. great companies

 

Dead on with the size of pipe. On my 427 w/106 it spooled at 3500 with 2.5 crossover to 3" merge. You want the smaller pipe crossover to increase exhaust velocity for spooling the turbo, depending on the size of turbo and motor.