So this is just preparing myself for what i hope are not coolant seals that are gone and need to rebuild. ive found this s4 t2 engine but its just the block that seems to be in good conditions, basically what i want to ask is....would i be able to use a s4 t2 block as an n/a??? What mods would i need to do, or would it just to better to make a t2 swap??? And if had to rebuild and needed housing could i mix and match any 13b housing and irons??? Would s5 rotors be difficult to swap for my s4 rotors??? I know its a lot of questions but im trying to see what are my options at this point....thanks in advance any advice would be appreciated.

 

you don't want to mix the rotor housings (S4 vs. S5) in any one engine. they have different timing. obviously, you don't want to mix rotors either (T2 vs. N/A and S4 vs. S5) because the compressions are different. outside of that, everything else is pretty much fair game. I like to keep front and rear side housings from the same series, but as far as I know it's okay to mix them (you may want to double-check timing specs to verify though).

to answer your ultimate question, yes, you can run the T2 block naturally aspirated. it's common practice to use higher compression rotors in them though.

 

Among other issues, the NA intake manifold is not a direct fit to the T2 block. Personally, I would not bother with mixing the parts, but some people like to spend a lot of work on things like this.

 

Thanks guys .....yea, basically keep s4 and s5 engines seperate and n/a and t2 seperate. Cuz if i might do a rebuild i think that i might be able to use the housing and rotors hopefully, but wont know until open that bad boy up, at the moment still running. But i believe i might have to replace the center iron for sure. And one last question is there a way a to tell bare blocks apart?? as in like s4 or s5 blocks or to tell from n/a to t2 blocks???

 

your questions are good, but before I answer, just make sure to keep in mind that people modify these engines all the time in all sorts of ways, so my answers only apply to untouched, stock blocks.

N/A = 6 intakes ports with baffles in the exhaust ports
Turbo = 4 intakes ports without baffling in the exhaust ports

S4 = EGR setup on the intermediate housing, no knock sensor provisions, mechanical MOP
S5 = knock sensor provisions, electrical MOP

 

Thanks guys

 

Kind of on the same note. I just got an 86 GXL and the o-ring grooves are broke out on the rear and center side housings. Are 1986-1988 N/A side housings the only ones I could use without major modifying? Also diabolical1 mentioned that you shouldn't mix rotor housings in any 1 engine but would it be ok to use a pair of S5 rotor housings? Will turbo rotor housings work for N/A with N/A Rotors? Thanks in advance. Very good forum with great users that know what they're talking about!

 

you can use the side housings from any Gen II N/A. aside from EGR passages (which may take some consideration on your part if you're shooting for a fully functional 100% stock setup), the only other difference I am aware of offhand is a thicker dowel area on the S5 parts.

for rotor housings, as long as they are paired by Series, you're good to use them. I would need to go ahead and look up port timing specs between N/A and T2 exhausts before letting you know if there's any other difference than the exhaust sleeves. unfortunately, I don't have timing specs memorized yet. however, what I can say is that you can use T2 rotor housings with N/A rotors, and vice versa, so in that regard you'd be good.

 

I really appreciate the help! When you say thicker dowel area would I need different dowel pins? Are these kind of known to break out the o-ring grooves and what causes that? Overheating? I've been a motorcycle mechanic for years but have only messed with rotary's a little so I'm a little green yet!

 

no. same dowel pin. just a more twist-resistant housing. it's a non-issue unless you plan to go with crazy forced induction at some point.

overheating seems to play a factor in broken coolant grooves, but I would imagine it's not the only factor.

 

Ya I think this poor car has seen some neglect! All of the apex seals were cracked and ate up the rear rotor pretty good. Thanks for all of your help!

 

Im sorry to randomly post but need help asap, and didnt wanna start a new thread, senior member please will are a s4 hood and s5 the same, i found a turbo 2 hood off a 86 i really want it??

 

Sorry to bring back a dead thread but I just had my n/a housings and rear iron stolen from my garage (who knows why someone thought they needed them...) I have two sets of pretty good s4 housings laying around though. From this thread I'm gathering that I can use do a mild exhaust port on the s4 turbo housings and use all the other parts from my s4 n/a engine and still be good to go. Is that correct? I don't have any other n/a housings and want to start my build without rebuying stuff. Much thanks

 

just to be clear ... you're asking if you can build your engine using a full set of S4 N/A side housings with a set of S4 T2 rotor housings?

if so, then yes. no problem. if not, correct my understanding.

 

correct. there won't be a problem if I use an exhaust port though right? Timing should be the same...?

 

If you're not porting the intake as well, leave the stock T2 exhaust timing alone.

 

My intake is a large street port. So I'd like to widen the exhaust port out, a bit down, rounded bottom, and smooth out the sleeve. As long as exhaust timing is the same it shouldn't be anything to worry about right?