I've got an 87 Iroc with the 5.7 350. I found a plenum, runners and a manifold from an 86 vette for sale. The guy is holding them for until I get back to him so I need an answer relatively quickly. Will this setup work with my engine? I know there were differences with the 86 vs 87 Camaros but what about the 86 Vette? Is the MAF and all that the same? Will it bolt right in? I appreciate any help you guys can lend.

Thanks.

 

USA-1,

The assembly will fit, except for the two center bolts on the intake base. The '87-up heads had the center two bolts drilled and tapped at a different angle than the pre-'87 heads. You can elongate the holes in the manifold base to allow them to fit,but to avoid stress on the aluminum casting you should probably mill the base at the correct angle to seat the bolt shoulder squarely on the intake. Another option would be to use tapered washer, but that would be tricky.

The EGR plumbing will have to be revised to use the external exhaust tube from the Corvette setup. Other than that, the assemblies are identical, MAF and all.

 

I'm new to this so that sounds a little complicated. What if I stick with the Camaro manifold? Will the runners and plenum fit on that? I know I'm gonna break something. Will I gain anything from these parts or should I just stick with the 87 Camaro parts I can get and make life easier (even though they are a little more expensive)?

 

USA-1,

Presuming you already have a TPI system on your IROC, and you're switching to the Corvette system, let me calculate the differences:

Runner length times area, runner diameters, :lala: throttle body bores, :lala: MAF diameter... carry the three - divide by pi - time the length - factor for RPM... Yup, just as expected. Your net gain will be about 0.00 HP and 0.00 ft/lb torque.

You won't gain anything from changing the TPI system to another one that is virtually identical (the only difference between the two is the EGR plumbing). You would do much better working with what you have and enhancing teh rest of the engine. You might want to consider changing the cam to something more like what the Corvette had, or even better. If you improve the exhaust, you will have already made up any differences between the 'F' car and the 'Y' car. The fact that the Corvette had aluminum heads is irrelevant, despite what other opinions people might have. Aluminum isn't good for any more horsepower if all other factors are equal.

 

You just killed me with that one! I thought they were the same but wasn't quite sure. The reason I'm asking is not performance but "beautification". I'm having someone port and polish some of the setup but don't want to lose the car now that the weather is nice so I'm picking up some extra pieces. What can I say, I like to spoil myself! Performance wise I will be going with an SLP catback setup very soon. I expect some minor increase by porting the TPI and changing the exhasut system. I'll do some other minor things from there. I just noticed about a 5 horsepower gain from the nice "Camaro" windshield banner I just put on. (Had to get you back).

 

just an fyi, the corvette L98 retained the old style heads right up until they switched to lt1 in '92. my '91 vette l98 has a one piece rear main seal, centerbolt valve covers and old style heads.