I’m building a custom manifold for my F20c, the flange holes are 50x43mm. I’m thinking of using 2inch sch10, does that sound about right? I’ll be getting 5 short radius, 5 large radius 90s and 2mtrs of straight pipe. Plan is to make a front facing manifold.


I know most of you will say - just buy one.... I’d like to attempt it myself, I’ve done my custom exhaust and I would really like to give it a go. And yes I will be back purging everything.

 

2" sch pipe is 2.375" in outer diameter. Typically most manifolds are 1.5" sch40 (1.90 O.D. - probably what you were referring to ). With a front facing manifold you will probably be fine with all standard radius 90s since there really isn't any tight turns necessary if the manifold is planned out decently.

There are head flanges that transfer the oval opening of the head to a circular opening of pipe. You won't have to form your sch pipe to match the head flange if you use one of these.

 

Appreciate the reply, I've already bought the flange, I could see if I can get it ported so they're round though

 

From my experience sch10 pipe always ends up cracking very fast. The manifold that end up lasting are always made sch40 pipe.

 

To be honest this will be my first manifold so I don't want to spend a lot, there's a few manifolds out there using sch10, I'm also looking at using slip joints on the runners but I'm struggling to find any in the UK.

Is there much difference between equal and unequal lenghts? Planning on running a gt30 and not aiming for huge power.

 

As far as I know, they do not make slip joints with thick wall pipe. I've only seen it with tubing, typically .063 / 16ga.

If you go tubing manifold, you need to support the weight of the turbo separately.

 

aahh that would explain why nothing comes up, well I’ll get it done in sch10 and see what happens.

 

I didn't know this until recently: pipe and tubing diameters are measured differently. Pipe uses the inside diameter (ID), tubing the outside (OD). What most of us call exhaust pipe is tubing.

-- Chuck