I hope it is not considered uncool or taboo to do this, but I would like to redirect you all to another thread. I am hoping that some of the History/Originality buffs here may be in a position to weigh in on the technical questions about swapping an earlier version TPI plenum with on a later version car.
here is a link to my Formula 350 page. https://www.thirdgen.org/forums/memb...ula-350-a.html

if anyone has experience and can weigh in on the questions asked in post #50, it would be much appreciated.

the question has to do with bolting up an '86 plenum to an '89 car with AS&M runners (for 89-up) and Edelbrock Vortec base (89-up.)

 

in 1989 a few things changed with the intake.

They removed the 9th injector
When they removed the 9th injector they also changed the plenum, and the left runners because the IAC would feed air by the 9th and that is how your idle was controlled.
Because they eliminated the extra port for the 9th injector the throttle body also changed, instead of having the IAC go through the plenum a portion of it was machined out by the dual port intake.

Really the only thing that relatively stayed the same for 88 & 89 was the injectors, and the Right runner probably wasn't changed, (heck I might even be wrong about that).

The Fuel rails were different (the 85-88 had a tube that comes off the Left rear of the fuel rail to feed the 9th injector)

I am running (get ready)
An 1987 intake Base
Runners that do not have the tubes for the IAC or the EGR, there is no hole for the 9th injector (I think) I remember that the 9th injector is laying there, unplugged...
an 87 throttle body where I machined out the space for the IAC to work...
1987 fuel rails.

For the most part I believe the pieces and parts all bolt up, obviously there are provisions for different designs. And some ECM programming would be required to get it all to work together.



John

 

Thanks for the input. The AS&M runners have the 9th injector port (mini-runner) plugged for 89 applications like mine. Do you know the function of the identical port on the passenger side which remains intact on 89-92 applications?

I am going to plug that triangular IAC port in ftont of the plenum behind the throttle body with permatex or something.

I might also try radiusing (rounding off) the openings of the AS&M runners since plenum ports are gasket matched leaving them now larger than the runner ports.

 

The small tube on the Right side I think is part of the EGR system. Mine does not have the tube, I had to deactivate it in the program, otherwise I would have gotten a code.

John