Hey all, I have a stock 1990 IROC-Z with the 350 tpi. Im currently getting an custom made mandrel bent 1.5" exhaust installed (custom because LHD->RHD conversion...), anyway, im sizing up my next round of mods for the car, what I am thinking is:

Vortec Heads
High flow manifold
big runners
58mm throttlebody
roller cam

I need some advice on which parts/brands you guys think I should look at, im not really worried about the price, im hoping for my engine to make it past 350hp. thats my goal.

I'd prefer parts that I dont need to have ported, but I plan on porting out the plenum.

I have heard the AS&M runners are decent ootb, and i shouldnt have to port a 58mm tb right?

thanks for any input/comment/critisism/abuse

 

As far as I know you will have to use the scoggin dickey intake manifold for vortec heads, but that isn't a bad thing. If you want 350 horsepower you'll definitely need to do some porting on that as well.

I think the general consensus on a 58mm throttle body, as of a few years ago when I posted here, was that it isn't worth the expense. Plus it can decrease throttle response. I'm sure you can find something if you use the search feature.

As far as the 1.5" mandrel exhaust, is that going to be true dual? Otherwise that will be way too small. Even 1.5" seems too small, as a good header for that size engine will have individual tubes that size or larger. Speaking of headers...

For a roller cam there are a lot of opinions but if you don't care about expense lingenfelter might have something for you. The LT4 hot cam and ZZ4 cams are pretty popular too and will get you 350 horsepower, but you'll definitely want some extensive porting to get there.

As far as abuse.. you suck!

Good luck.

 

1.5" from the block to a 3" system, my iroc has the dual cat option, so i think i will just leave them in for, but im getting the cat back done aswell to a hooker aerochamber

 

Are you sure you don't mean 2.5" from the manifolds to a 3" system? Don't do 1.5", mabey 2 or 2.25" but not 1.5.