I have changed my mind from a top mount to a sidewider manifold. I plan on building it with 16g Mild steel. With my Design NO weight of the turbo will be on the manifold so this material is fine.

What size should I use? I can get 1.5" or 1.75". What would be better. SHooting for 320-350whp.

 

i'd go with 1.5"

 

i say 1.25

 

what size turbo you runnin? bigger turbo=smaller runners. and visa versa

 

why would you want smaller runners?

 

smaller runners keep exhaust puses closer together where they have more energy to spin the turbine wheel. Kinda like how a t4 has a divided inlet, to keep 2 seperate smaller columns of exhaust gas together all the way to the turbine for more energy. Basically, it spools the turbo up quicker

 

WHAT?

anyway you realize that 1.5" pipe used for makin manis is larger than 1.5" ID right? so if you get 1.5" 16g steel it will be 1.5" outer diameter and even smaller ID. id get 1.75"

 

there should be a calculator for this beacause a small runner will help spool up but can choke up top. i would aim for a 1.5 id just because that seem to be what most manifold are made with. if you cant get that then get the bigger one not smaller

 

does anyone even read what i post?

 

Ya I read it.

I went with 1.5". I know the difference between Pipe and Tubing. If this ends up being too little for my goals I will just re-order my pipe and build a new one. No big deal. Pipe was cheap locally and a $4 difference between the 2 sizes.