Alright, I gave myself a headache thinking about this, but does anyone know a good reason to get the aluminum FD rotor housings (not the plates) as opposed to the aluminum GSL-SE housings? I'm planning on staying NA, and the only differences between the two that i can find from pictures and outside information is the fact that the FD housings have a hole for the knock sensor, have that third hole for the turbo exhaust manifold, and are $300 more expensive.

Since i am staying NA, is there any reason to get the turbo housings and pay $600 (2 housings) for an extra exhaust hole? Or am i getting something more? I've already ruled out the S4/S5 NA housings since i plan on street porting them and don't want to have to deal with those exhaust diffusers.

If this question has already been answered, can someone post a link to that thread? I couldn't find one, but i may have just been using the wrong combination of words... Thanks!

 

no difference that i know of. except the gslse housings can be used with the 12a irons. turbo housings will have no plate thing in the exhaust port. other than those 2 things i dont know if the 13b housings are anymore different from each other.

if im wrong feel free to correct.

 

FC and FD engines have water seal grooves in plate not housing

GSL-SE ( resi ) engine ( 85 ) is similar to the older rx4 housing arrangement
with water seal grooves into the alum housing
( yet provision for an oil injector, albeit closer to inlet than later FC and FD )

you must use the correct housing groove style
( or be prepared to groove your new housings or old irons )

the trochoid is also slightly revised ( tighter ) in housings intended for the 2mm seals

 

So then if i were to (for instance) use a FC center plate with GSL-SE housings, what would happen? (since there are grooves for the water seals on both parts) Because of the water seals grooves, are the S3 housings even compatible with the later series center plates?

 

85 and before- swap away
86 and later - swap away ( rx8 exception )
any housing/ plate combos that jump between the 85 /86 change require water groove mods
( not impossible, but cost prohibitive )
a set of grooves in plate, with a set in housing sounds like disaster to me
( or some custom water seals )

if you want a decent centre plate for a RESI engine housings
you have 3B and N grey or Y grey early 12a or 13b options
( but you lose the fuel injection points, and centre engine mount )

personally, jump straight over to an entire post 86 block as basis
using s4 or s5 6 port engine, your resi stuff will bolt up
( but i much prefer the 4 injector s4/5 setups )


the s4/5 six port engine brings better porting already
also allows use of s4/5 turbo centre plate for even better porting potential
better oil pump, lighter rotors than RESI engine
and s5 has 9.7:1
( and both bring better inlet and potential for sequential injection )


the silly exhaust baffles come out easily if you dig out the roll pin heads and discard the entire port insert
( i just port match my extractors or turbo manifolds to suit the lack of insert )

 

Thanks bumpstart, that last post was everything i was looking for.

Not too worried about injector holes since i'm planning on going ITB anyway.

Thanks again!