I have a 87 n/a. I need to know if u can put an s/5 manifold on the s/4 block. But need two know how much more h/p does this give. Is it worth it. And i dont think it just bolts up so how do i do it. By the way searched this forum cant find what i need but a good link would be great.

 

I'm not sure about the fitting but i can tell you that the horsepower difference wouldnt be substantial enough to justify putting one on. The increased horsepower in the S5's was mostly due to the lighter rotors and higher compression.

 

Thx. Thats what i thought wouldnt be worth it.

 

alot of the HP gain is from the higher comp ratio, but one thing about the s5 is the VDI intake makes a tad more hp, but its at higher rpms!! ( notice s5 peak is at 7K instead of 6.5K) which is from the better intake design and not the comp ratio..

you want to use the s4 lower intake manifold, port matched to the VDI upper intake, and s4 Throttle body. this would probably give you 5 more hp and a higher peak HP rpm,so longer power band , and less drop off past peak....

you would need some type of solinoide to activate the VDI at about 5800 rpm, if you want to get max hp, having it activated before that would hurt your mid rpm range hp.

 

Cool sounds good. Will give it a try. Btw if i do this i understand i can shift about 500 rpm's higher.

 

well im not sure how much exactly but its better for higher end power..... that with a fulle xhaust will net you a higher rpm hp peak for sure.

figuring out how to actuate the VDI will be the hardest part.. you will probably need some kind of soliniode to move the thing back and forth..... or an electronic valve hooked to an airpump or somthing...

 

k. is there and post/ or site with this one how to do it step by step. Ya i have n1 exhaust with bonez test pipe and street ported so it will be very good for high end h/p. But a good link would be awsome from anyone.