Can anyone tell me if there are any cast iron factory or aftermarket manifolds that work well with TPI units? What size exhaust opening would a stock 86 305 exhaust manifold have? Are any of these worth having worked over to keep up stock appearances? Thanks. Jess

------------------
Blue '86 IROC, 305 TPI
Ported Plenum, gutted air boxes, FastChip, KN filters, TB Airfoil... more to come. Not raced yet. 70,000 original miles. Owned since 1992.

 

No. The best flowing manifold that will fit on the thirdgens is the one that comes stock on the TPI motors.

------------------
The IROC Homepage
View the Restoration of an 85 IROC
Weekend projects aren't.

 

Actually Jim, there was a revision in the later years where the stock manifolds flowed better than the ones of the earlier years. But they all flow like crap so there is no gain in swapping to anything OTHER THAN headers. If you are looking for performance from factory GM parts, you're barking up the wrong tree... on the wrong continent. Go aftermarket and say screw looking stock.

 

Yeah, all the TPI motors got the 2 1/4" outlet manifolds. That's as good as it gets on an old Gen1 small block Chevy. For stealth you might have them extrude honed for about $150-200, but it still won't be close to what a set of cheap tubular headers will get you.

 

Thanks for the notes guys. If I recall, the old rams horns Vette manifolds were 3" openings, and there are repops available for about $200 a set. I was just wondering if there was a performance way to go without the general problems related to headers. Thanks again. Jess

------------------
Blue '86 IROC, 305 TPI
Ported Plenum, gutted air boxes, FastChip, KN filters, TB Airfoil... more to come. Not raced yet. 70,000 original miles. Owned since 1992.