Hey guys,
So im wondering what the difference in intake ports between the two actually is (a picture would help me a ton). Same thing goes for the exhaust ports, are they the same?

Is it possible to mate a S4 LIM to a FD UIM using a adapter plate??

Thanks a ton!
Dan_s_young

 

s4 ports and s5 ports are basically the same or...are the same.

Why would you bother putting an fd uim on a 13bt??!

 

not 100% sure on the port similairity, but its close enough that the manifolds can be swapped without issue.

FD UIM on S4 LIM? It'll work fine with an adaptor plate.

https://www.rx7club.com/forum/showth...4&highlight=FD


Why put it on you ask? Looks. Better functioning TPS, better flowing (very negliegible) due to lack of bends....however as I said its negligible.

 

Easy one first...
Exhaust ports the same.
Spark plug locations are DIFFERENT.


Intake ports?
In the side irons?
Secondary intake ports on the side irons are the same.
Primary intake ports in the center irons are DIFFERENT; the S5 ones are SMALLER - they open up 10-degrees later.


-Ted

 

Exhaust ports on all 86+ rotaries are the same size, except the funky cosmo motors.

Intake ports on the s5 turbo are 1/8" larger in width (where the LIM bolts on) than the s4 ports, but the port timing/shape inside the iron adjacent to the rotor is identical. The Intake runners are also just a hair larger, and their locations shifted slightly, which is why you cant mix series of intake manifolds.

I have never heard of anyone mating an s4 and s6 intake set, because the difference in port location will be even more than it is with s5/s6 crossbreeds (which also require an adaptor). The s6 port runners are probably spaced a good 1/4" wider than the s4's. I have both gaskets if you'd like to see.

 

^^^ If its possible for you to take a picture of a S4 LIM gasket (where it mates to the UIM) and the same with a S6 LIM gasket I would appreciate it so much!

I already have a adapter plate for a s5 to S6. But I don't know if it would be possible to modify it by the way you are describing the ports (1/4") further appart.

And as to why I would want to do that? This is the reason (BTW my adapter plate is in the picture):


Thanks!

 

In order from top, s4, s5, s5 turbo gaskets...



s4 vs s5, note the bolt pattern difference...



s5 vs s6, again the bolt pattern difference...



s6 vs s4...