I've been doing some research on T4 manifolds. I've seen a divided T4 manifold with dual wastegate setup. Classicauto was able to answer me that, reasons for dual gates, the largest being that you get to maintain *FULLY* divided runners. Even a true divided manifold will have exhaust pulses mixing in the wastegate runners where they collect - the true dual avoids that.

But I wanna know how beneficial is that in terms of response, power and reliability ?

 

check the single turbo forum for this stuff

 

A fully divided manifold generally means you spool much faster (200-1000 RPM quicker depending on turbo) and have far better boost control.

 

this is 2a+Ron 's setup, from this thread: https://www.rx7club.com/single-turbo-rx-7s-23/opinions-dual-wastegate-vs-single-807268/

he is using a 4 inch downpipe with dual Tial 44mm wastegates... you are looking 700+ dollars just in wastegates right there, and if you paid someone to make a manifold like that it would probably be like $2000 because of the labor

they're great but the cost is prohibitive obviously.

 

Alright and what If I were to use a 3 inch downpippe and 2 38mm wastegates ?

 

Seems reasonable.

The picture posted above does not have any flex sections for the wastegates. I suspect cracking will be a problem as stainless steel moves a LOT when it's heated.

 

would stainless steel move or expand even if it were ceramic coated ?

 

Yep.

 

So flex dump pipes would be the better alternative ?

 

Here's a shot of my dual 38 mm setup.

 

Well, if they're dumping to atmosphere, you can just use a solid piece of pipe off the wastegate. If its re-routed into the downpipe, the issue is with the two pipes merging and heating/cooling/expanding/contracting of the two different pipes. It can work, as seen in the case above, but its recommended you put a flex section in to account for the different expansion/contraction rates of the different size tubing + the fact that there's just so much movement between the mani. runners, the wastegate runners, wastegate, dump, and downpipe.

I believe in 2a+ron's case he's very limited on space so flex sections probably were just too damn hard to integrate.

RCCAZ - I love that setup. Saw your thread on R C C and its looking like a real monster!

 

A flex section midway in the downpipe may even be enough if there's no room to mount flex couplings on the wastegate piping.Idealy both would be a good idea with Stainless steel.

 

Thank you to both arghx and RCCAZ 1 for reference pics and props to both of you, very nice lookin setups, sexyness at it`s best.

RCCAZ 1 what size downpipe do you have on your setup ?