im rebuilding an 88' non-turbo and found out an apex seal blew in the rear housing and i cant seem to fing the rear housing or rear rotor they seem to be NLA from all websites ive seen any help would be greatly appreciated

 

the rotor housing shows as available, but they don't have any, and none on order. things are so bad, if you ordered it now, it would be February before it got here, at best
rotors are the same, so you just need 2

 

You can try the classifieds section if you want to save some money. Can look for a S4 na rotor with the rotor weight within 1 letter difference.

can also find used rotor housings. S4 na works, but I think a s4 t2 would also work. If using the t2 housing, you can change out the exhaust port diffuser. Visual inspection is a little difficult but check the fsm to see what’s within specs.

 

whats the classified section?

can you mix turbo rotors and housing with na rotors and housings?

 

Rotors, absolutely not. The two rotors must match and have the appropriate counterweight. S4 NA set, or S4 TII set, plus an S4 counterweight. Or S5 na set, S5 TII set, plus S5 counterweight.

You can put both S4 TII rotors into an S4 NA engine as long as they match. However, you will lose power compared to the NA rotors from the lower compression ratio. They're also typically more expensive.

You can put two NA rotors in a TII engine, but you will be closer to detonation at any given point due to the higher c/r so you need an ECU to tune it.

Housings, the short answer is no. The long answer is that if you block off the coolant port on the intake side in a turbo housing, you can use it in an NA engine. However, you also need to swap the exhaust sleeves to match. NA sleeves have a diffuser, turbo sleeves don't. For maximum power you want no diffuser, for quieter exhaust you want the diffuser. Again, both housings must match (two with diffuser, or two without diffuser), don't mix them. There is no problem with an NA engine without diffusers, it will just be louder.

For a TII engine you can use the NA housings if you swap the sleeves out for TII sleeves and you source your turbo coolant from a location other than the stock one on the manifold. You could hypothetically keep the NA sleeves in both housings in a TII setup but this will hurt spool so it's a bad idea. The turbine wheel already quiets the exhaust down.

So it can be done, but it's a bit of work.

EDIT: I now see you're building an NA, so you can disregard the sections about building a TII engine.

 

I see...
Do you know where to get na s4 housings and rotors?

And also can you get the housings and rotors serviced to re-use?

 

Classifieds section is found on the main page. You can hope to find someone selling usable rotors and housings. Check the fsm to see what constitutes being reusable. You may be able to just reuse rotor and housing, or may have to install a new bearing into the rotor.

 

I think TII housings would be preferable due to the lack of the exhaust diffusers. I don't think the noise increase would be enough to worry about.