Anyone know the diffrence between a 90N/A rotor housing and a 87TII....?

 

TII have a different exhaust port sleeve,

 

Jeez that was quick... So can you use the 90n/a's on a T motor...?

 

Not without hindering exhaust flow. A common NA upgrade it to use TII housings with the tradeoff being a louder exhaust note; due to the lack of a diffuser

 

The only real diffrence is the Exhaust ports... Cant you just port the hell out of em to make up for it..?

 

another, more important difference: the t2 housings have a coolant passage at the top corner, which would flow into the lower intake manifold, and into the stock turbo. The only way you could use an NA housing in a turbo engine is to place it in the front position (where no coolant flow is required), as the rear housing on a turbo supplies the coolant, though they made both housings with a coolant passage there...

One more little thing; the s4 (86-88) and s5(89-91) generations had a bit different plug timing...line the 2 up and note that the s5 has a lower leading plug hole, by about, oh, 1/4". This wouldnt mean the end of the world if you mixed them, but all the same, I would not try to mix them.

Bottom line, its ok to use an NA housing in a turbo engine only if 1) both are 86-88 (s4), and 2) the NA housing gets put in the front position of the engine.

BTW< if you have your old t2 housing, you can remove the exhaust sleeve from it, and re-pin it into the new NA housing to avoid having to grind it out on the NA. The hole in the housing is the same, but the steel sleeve is not.

 

Thank You. That most certianly answered my question.