I'm not sure what I'm asking, but if I was to buy the housing and rotors out of a FD 13b could I use them in a FC 13b and would it be any better.
Keep in mind this is just a N/A because I don't want a ghetto TII. (No offense)
I searched this and didn't really find anything, but I'm sort of blind/stupid.

 

the FD housings are superior to the FC due to chrome surface improvements, just use a set of two and you'll be fine. The rotors are pointless to install, the compression is lower than even an s4 n/a and you'd have balance issues.

 

Thanks, would you know if they would be any significant horsepower/torque increases ?
I'm planning on doing a mild streetport whenever I rebuild soon; if that makes a difference.

 

With the housings? None. You will have better lubrication, and more wear resistance.

 

the timing of the plugs is different than an S4 rotor housing's. you'd have to experiment with timing the CAS to avoid pre-ignition. (the plug timing split is also wider)

but yes, the housings are superior.

 

The timing difference is mentioned with the S4, is it different with an S5? Do you have to run two FD housings, or can you run a FD and an S5 housing together?

 

what? turbo rotors were purposefully designed to be lower compression than na rotors..

you do have to run two fd housings or two s5 housings. i think the differences are minimal but as stated before, fd housings are still better than s5.. timing is different betweein fd and s4 though. also remember if this is a turbo car, the fd housings will not have a water port for your turbo.

 

he said this is a non turbo build. there's no point in lowering the compression then.

 

ah i missed that part. thanks

 

sorry dont mean to thread jack but can you run fd turbo rotors in a s5 tubro housings?? if so any difference?? i also see people talking about how they got lighter rotors where exactly do they get these from??

 

From everything I have read they are interchangeable.

 

So how different would the ignition timing be versus a s4 na housing? Is the timing retarded or advanced compared to the s4 na?

 

actually S5 and FD rotor housings are pretty much identical as well as their spark plug timing, just the FD doesn't have the coolant passages ported. you just can't mix an S4 with an S5/S6 housing, you will break a side seal if you try to run any reasonable amount of power through it(the rotors won't be in constant power phase with each other and will be fighting one another). i just haven't checked the port dimensions of both so i would check them with a template if you plan on using an S5 and S6 housing together.

the timing of the housings between S4 and S5/S6 have more split, they have about 5 degrees more split in their location in the housings. j-spec series 4 engines also have the same spark plug timing as S5 and S6 do.

s5 turbo rotors and S6 rotors are identical.

 

ok does that mean s4 and s5 rotors are identical too? because i thought they were interchangable too

 

The S4 and S5(turbo) rotors have different compression ratio's.

S4 NA rotors are 9.4:1 S5 NA are 9.7:1 & Rx8 rotors are 10.0:1
S4 Turbo rotors are 8.5:1 S5 Turbo rotors are 9.0:1 & FD rotors are 9.0:1

 

oh ok so where can i get lightened rotors?

 

Racing Beat sells them, but they're far from cheap, and far from necessary for 99.9999% of builds. Only full on race cars in very fast classes would get the full benefit from them. They're not required for street use by far.

 

You're talking about using 1 s4 housing and 1 s5/s6, yeah I agree that would have problems. But I'm swapping both housings, so as long as both are of the same series I'm ok right?

How would the change in split timing effect running if I swapped them in place of s4 housings?

 

Yes, in theory... everything sounds better in theory.

 

yes

and i haven't measured the differences in timing, the ECUs are mapped differently timing wise which compensate for the differences. i just try to avoid experimenting with stuff as much as possible, on the safe side retarding the timing a few degrees and you probably would never notice there is a difference.

 

Ok thanks. Thats what I needed to know.