I have the opportunity to pick up a used tpi setup pretty cheap for the purpose of polishing it in my spare time, so as not to have any down time on my iroc. The question is, since the 87 was still equiped with that 9th injector, can I still use it with my 89 setup. It seems like the runners on my 89 would cover that extra hole. Is this true? Thanks guys

Will

 

Yeah, as far as I know the plenums are identical. The 9th injector goes through the bottom flange of the driver's side runner, and straight into the intake manifold anyways. So hopefully no problems for you

Matt

 

Wrong, there is more differences than the injector hole.
Plenums and runners are different. The 1987 Iac passage goes thru the plenum and down the runner. the 1989 and up there is a slot in the TB that feeds the air into the engine. You can tell the earlier plenum has a triangle hole in between the throttle bores. the 89-92 has no hole.

 

Yes.
I had no problems running an 87 plenum on my 89 car. Then I also installed some LTR from the same 87 car on my 89 car. All I did to thr runners was quick steel the hole for the 9th injector.

You would have problems running an 89 plenum on an 87 car I believe. Not the other way, though. At least no problems on my car.

 

Well this is interesting. I think I may have a problem on my 87 Camaro then. Tell me what you think. Here is my setup. 92 LB9 block, 86 ECM with 89 PROM, 86 plenum, 86 throttle body, 89 intake manifold, 89 or 90 driver side runner (not sure of year but it's the later style without the cold start hole), and 86 passenger side runner. So if my plenum is directing the IAC air down the runner I'm going to assume it's hitting a wall due to the 89 manifold. The car does run a bit rough when cold, and I always assumed it's because I don't have the IAC adjusted just right, or possible something else is off. It's not the PROM, as I'm running an 89 PROM to compensate for the lack of a cold start injector. So watcha think, does my IAC valve have nowhere to send the air?

 

The IAC differences can cause problems when running a newer plenum with an older throttle body, but an older plenum will work fine with a newer throttle body.

If you do have a new plenum and old TB, just drill a 1/2" or 5/8" hole in the proper spot and you're good to go.

 

Thanks Jim. both my TB and plenum are from an 86, so I guess I'm ok.

 

That just means the throttlebody matches up with the plenum hole. you still need to have the correct runner and manifold to complete the passage

 

Any difference in the lower manifold? I will be keeping my tb, which is off the 89. the only thing I see different is the hole on the plenm/lower intake, which is covered anyway by my runners. Do all TPI lower intakes have the provisions for the 9th injector passage? Or was it not present on the 89+ models

Will

 

the 9th injector hole has nothing to do with the IAC passage.




http://www.turbotime.us/gallery/bigtime01

 

Well it's not worth it for me to change my manifold at this point. For one I have no cold start valve, and I'm running an 89 chip, so I'd prefer to keep my 89 manifold. Can I simply go with the later style throttle body?

 

I would keep the throttle body, get a late plenum, drill the hole.

 

I think for now I'm going to leave well enough alone. My plenum is ported and I don't want to deal with porting another one. I suppose this is what I get for cobbling a system together. I suppose I shouldn't really bitch considering this is the only real compatability problem that has come up. After all this car used to be a 2.8 V6, and we did the V8 swap out of whatever I could get my hands on. It's a real Frankenstein, but it's been running fine for 2 years like this. The other issue is that right now the car is not in the same state as me. I left it with a friend when I moved a few months ago, and I'm not likely to see it for at least 3 more months. Thanks for the info though. You have been a big help.