I need to know if the s4 throttlebody bolts up to an s5 intake and everything lines up internally (such as the air passages.) What are the other differences? This is completely non-stock application (standalone computer, no emissions, etc.) so most of the differences won't matter, but I'd like to know what they are.

 

I think the main difference would be the OMP lever on that S4 TB. As far as air lines, I would have to look at the manifold and the TB. Is there a reason you want to put an S5 TB on an S4 car?

 

he's probably running S5 manifolds on a S4 car. bigger intakes ports I guess, but needs the S4 throttle body to use the single TPS and mechanical OMP.

yes you can do it but jrat is right. the OMP and TPS is where you'll have to worry about.

 

It's the other way around, actually. I want to put the S4 TB on an S5 intake. The motor will still be S4 (and it's going in a VW.) I'll have the S4 OMP as well. I want the S5 because it supposedly makes more power. I just don't know if the early TB physically bolts to the S5 manifold and whether it will require any porting.

 

The added power comes from increased compression, and redesigned intake paths and opened up ports. Just putting an S5 TB on an S4 motor will not yield any HP that I can think of.

 

Thanks, that's what I needed to know.

Actually, one more question. Does the S4 fuel rail fit the S5 manifold?

 

I have a set of S5 rotors to use, I'll be porting, and I'll be using the S5 intake. NOT the S5 throttle.

 

Okay, I was getting confused. I assume you will be Premixing? If so I would guess the S4 TB will bolt onto the S5 Mani.

 

No premixing. I'm going to use the S4 front cover and OMP. With the S4 TB, the oiling will work like stock as I understand it.

 

Wow, this is mind bending. I havent actually done this (I did an S5 swap with S4 uppers), but the only issue I could see is the placement of the TB relative to the OMP, which might require fabrication of a custom OMP rod (people have used Coat Hanger wire for this purpose). Other then that, I am not the expert on putting an S4 TB onto S5 uppers.

 

I've always wanted to use a coat hanger on my car, so that will work out great. Thanks for all your help!