jetson8859

All,

I'm in the process of starting to build my GT engine. I have the cams and heads and had a question regarding the 4R manifold. In doing some research it seems that the heads and manifold were port matched to some degree.

I have the original 4R manifold as well as another 4R off a GTS. The GTS manifold is already cleaned and powder coated the correct silver whereas the GT manifold was powder coated a dark blue. My question is simply would I see any appreciable difference between the 2 4R manifolds?

There are no differences in part numbers or markings on the 2 manifolds that I can find so wasn't sure how much performance difference there would be between the two.

The GTS manifold allows me to start putting things together this weekend whereas the blue GT one will need to be stripped, powder coated and cleaned which will cause about a 3 week delay.

​​​​​​​Appreciate the input.

Jerry Feather

I think blue is a much more powerful color than Silver.

Rob Edwards

If you could measure a performance difference between two 4R manifolds I will buy a Rogerbox.

jetson8859

Thanks that what a thought, asked the question based on following statement regarding differences between the S4 and GT engines. Sounds like I can get started this weekend.

Intake Manifold

The GT engine uses a 4R intake manifold which was used on all late model 928s. What is unique for the GT engine is that its intake manifold included port matching with the cylinder heads. The cylinder heads were hand picked to match up, and this increased the CFM (cubic feet per minute) rate for the intake.