Are all TPI plenums the same... regardless of year. I found a guy who has a nicley polished plenum from an 87 Bird. Will it match my 92 maro 5.7??

 

from left to right
85-88
89
90-92

bottem pic
85-88
89-92

a 89 plenum will work on a 90-92 speed density sysyem but you need to drill and tap a hole for a vacume port.the map sensor needs to have a dedicated source.

 

Nope, they're not the same... The 85-88 plenums will have a cold start injector passage on the side along with the idle air control passage on the front of the plenum...

EDIT: Damn, beat me to it... thats the pic that illustrates it though...

 

What is the triangular cut out for on the throttle body side?? Any tips on how to add the set up for vaccum?

 

Thats the idle air control passage for the early style '85-'88 plenums...

 

thanks Thirdgen88.. after reading your first reposne (again), I noticed you mentioned that.
Will the AIR Idle have any performance impact on my 92? I know I'll have to add the vaccum, which I suspect should not be too difficult.. but I don't want to create much more work or problems with going to an ealier plenum. I am considering the swap. basically, just for looks.
Thanks again

 

the 85-88 plenum wont work on a 90-92

 

From what I've read....the earlier style plenum will work on the newer style, but the newer won't work on the earlier. Atleast I hope so, 'cause I have an 85-88 ported plenum that I plan on installing on my '89 GTA in the spring.

 

Please delete this post..... it wouldn't let me get rid of it.....

 

I am also in the process of using a MAF (earlier style) setup for the MAP setup. The MAF plenum should work fine for you. 91bandit2, If you search through all of the tech articles you will find that it is do-able and people have no troubles when finished. You can T off of another line for the MAP sensor because all you need is a good vaccum source. Then just mount the MAP sensor on the cowl. You can plug up the Idle air tunnel on the passenger side.

 

that's what i did for my 305 tbi to 350 tpi swap.......but it didn't work!
i went from a 89 plenum t'ing off another vac line,i could'nt keep the car running above idle.i check voltage every where,replaced the TPS and the IAC,dicked with the timming,etc,ect,ect

i was lucky enough to be given a 91 corvette base,runners and plenum.i installed that plenum and gave the MAP a dedicated vac sourse.fired it up and ran like a dream.

there's my last .02 take as you see fit

 

what about the intake baseplate,are they different(aside from the 9th injector port).i bought a 92 camaro with a MAF setup but it has a 92 ecm(the guy dropped a motor from an 87 into it along with the tpi)he has the map sensor mounted a little to the left of the distributor.i went out and got a map plenum.i plugged the 9th injector air tube on the runner.the idle was way down(im assuming its from the maf TB on a map plenum)other than that it seems to be working its just the idle is a bit too high.so the point of my question is.if i go out and get a map runner will it bolt up at the base plate correctly or do i need to get an intake manifold as well? (along with the map TB)

 

Had you thought of using an AFPR in place of the stock FPR and then using the now free Vaccum line from there? Because that works and you don't have to T off of anything at all. Did you check the vaccum from the line you T-ed off of? Did you try T-ing off from other lines? Was there a vaccum leak at the gasket that you unknowingly corrected the second time? Did you use all the same sensors? Not trying to be a smart ***, just trying to figure out why it did not work for you. If you wanted to try something else you could drill, tap and die a new hole and then buy a fitting for the plenum.
Why would you use the Corvette fuel rails since they have a slightly different fitting location? You had to buy/convert your existing rails. I have also read how the corvette TPI intake is different because The '87-91 Corvette intake used a heat-riser tube off of the passenger-side header and has a water crossover at the back to relieve hot spots on the back of the aluminum heads. Did you already have Corvette aluminum heads?

 

nexus6 all of the bases are the sams except the corvette base

Tibo i did check for vac leaks check my vac source.i did not try t-ing off another vac line.
i didn't use the Vette base or fuel rails cause i don't have any

 

Interesting. THats what I did on my '89 when I switched to map. Though, I have the whole thing apart right now i'm gonna tap another vac port just for the map for safe measures.

My adjustable FPR (I made) still utilizes the vac line. You want to have the basepoint (idle) adjustable, but still have a slight increase with vac decrease (wot).

-- Joe

 

thank you for the info

 

Hmmmm, don't know if I should've started a new post for this one or not, but this post got me thinking about a couple of questions with my tpi setup. I've got an 88 tpi unit that I'm going to run with an 89 wiring harness and ecm. I plugged the the outlet in the end of the fuel rail for the ninth injector and made a block off plate for where it fits into the the base. Is there anything else I need to consider or will it work okay set up like this with the 89 ecm and no ninth injector? I figure they're both MAF systems and the only obvious difference is the lack of the cold start injector setup on the 89 system. I also made sure to get the 88 throttle cable for the 88 tb. Any tips or things I might be overlooking would be very appreciated!

 

All baselates have an opening for a ninth injector.
The only difference in baseplates are the angles of the bolt holes for centerbolt style engines and standard style engines. Then the corvette intake is slightly different. The cold start should be blocked off at the end of the fuel rail and on the runner.

However, depending on how you've plugged the hole on the baseplate, it still may work fine.

 

All I did to plug the hole in the baseplate was to make a plate out of steel that fits over the injector hole in the runner base. It has a hole in it so I can clamp it down using the bolt that holds the ninth injector in. I'm going to use a little bit of silicone on the plate before I bolt it down during final assembly. It's basically the same method people use when making their own egr block off plate. I've also seen similar plates for sale by accel I think or edelbrock for blocking off the ninth injector. I figured I could make my own easily enough though rather than spend the cash on one of theirs. The bolt hole angles aren't an issue since the base I have is from an 88 f-body and the tpi unit is going on 88 L98 cast iron heads.

 

i just stuck the injector in ,but i didn't plug it in.so no fuel go in it but its sealed.eventually i'll get some slp runners.