im considering buying a ported stock turbo mani for use on my 12a [fb rx7 ] to do a s5 turbo setup.. how can i tell if the manifold im gonna be looking at is for a s4 or s5 and do the turbos mount up diffenrent or the same and which manifold is better of are they the same

(Tried searching didnt come up with anything useful)

 

S4 turbo manifolds have a weird shaped outlet, and a distinct flapper. It's also angled. The S5 manifold outlet is parallel with the inlet, and the outlet has 2 even oval shaped ports.

This is an S4 Turbo ehxaust manifold:



S5 Turbo exhaust manifold:

 

so if it comes straight out its a s5, any flow difference between the two manifold> i know the s5 turbo is better then the s4 so i guess s5 turbo and manifold for my 12a

 

Sorry. Not going to fit. The 12a will be too narrow for it to bolt on.

 

how are you going to mod the manifold?

you do know that its not a direct fit

 

sorry yea i know its not a direct bolt on, there are many threads on how to modify and grind away metal from stock 13b mani for it to fit on a 12a, i just need it to where it clears my rb holley manifold..

also so the s4 has a weird bolt pattern but the s5 looks normal any other turbos that will bolt to that?

 

Don't think so. You could go with an aftermarket manifold if it's turbo availability and flexibility you're looking for.

 

most aftermarkets wont work with my intake and im sure the s5 turbo will work perfect for my setup just was wonderin

 

Take a look at this. If the turbo won't clear, you can make a spacer like Aaron did:

http://www.aaroncake.net/RX-7/naturbo.htm

 

any difference in exhaust flow one over the other looks like s4 has bigger hole but i know the s5 turbo wont work with it

 

I'll tell you this much: I had an S4 turbo, then swapped to an S5 and I'll never go back. The S4 has the "Twin Scroll" flapper that's supposed to direct exhaust gasses at a certain angle to get the turbo to spool faster. Mine didn't work, and I could barely get the damn thing to work properly. The S5 turbo spools up just fine without it. Other than the hot side, the turbos are the exact same. The wastegate is improved on the S5 as well, so boost creep is less of an issue.

The S5 turbo will not fit on an S4 manifold. I'd say that regardless of whether the manifold flows better, the S5 turbo just is better all around.

 

The S5 is divided, and the S4 isn't. That's all. A divided manifold will help the turbo spool up quicker.

And to answer your previous question, there are no other turbos that will bolt onto Mazda's exhaust manifolds. They are proprietary shapes.

 

HT18S-2S anyone have the a/r specs and sizes for this turbo

 

You're not going to find a compressor map the stock turbo, but this will give you an idea: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/stock-turbo-wheel-size-818137/.

The compressor housing is 0.5 A/R, and the turbine is 1.0 A/R for both S4 and S5.

 

thanks!! well guess ill be on the hunt for a s5 turbo now!

 

i found this mani. http://rotorzilla.com/parts/cat-6/Turbo-Manifolds.html Maybe it will work for you.

 

Is there any difference between US spec vs JDM exhaust manifold on S5?