s4 manifold with s5 rotor and housing
 

Alright, so basically, I want to buy a new (used/rebuilt) motor rather than rebuild my current one (212,000+ miles). The motor I am looking to get is an 89 gtus motor with a small port job, and s4 intake manifolds, and etc. So its going to be a s5 motor(rotors & housing) with s4 components. What do you guys think, would it make good, power, and how much would it be worth, if its even worth getting at all.

it doesnt work i had an s4 intake on an s5 and there is an exaust port on the s5 for the exaust gas reentry blah blah and the s4 doesnt cover it sounds like a bad exaust leak under the hood and if u drive it like that u could catch fire, mine did aHHH

^^ lol that must really suck =/ hope everything is ok now...
TwEaK

if you're going with little or no, or "small" porting in your case, the s5 intake manifolds will yield more power with the vdi setup......also, you'll beable to work 5th/6th ports with the airpump......IF i were you, id look around on the forum and buy a set of s5 manifolds for like $100

I have a S4 manifold on my S5 block, the lower intake manifold anyways.

Here is the problem you speak of photographed:
http://pengaru.com/~swivel/cars/rx-7...w_IMG_1817.JPG

And here is the solution:
http://pengaru.com/~swivel/cars/rx-7...w_IMG_2186.JPG

$25 later and there was a block of aluminum added to the bottom, get to know your local machine & welding shops.

I think he only used the lower manifold.