johnny89345

i have a 87 iroc with a 5 speed and 342s. i want to keep it as my daily driver so i want to keep the compression between 10-10.5-1. i have a forged 355 with a zz409 cam and 1.6 roller rockers. my tpi setup is all aftermarket and highly ported with a 52mm throttle body and 24lbs injectors. i dont know what size heads will work well for me. i was told afr 195s would be perfect but i dont know i want to see what you guys think. also im going to have tpis burn me a chip once i finalize what heads im getting.

Blackdog36

iTrader: (3)

Have you calculated compression ratio or know engine stats (piston depth, bore diameter, piston dish/flat)? That can help us narrow down a combustion chamber volume to get good compression ratio. Probably will be looking at around 60-65 cc chamber volume.

AFR's are a great choice with their low lift numbers. I'm looking to upgrade my 350 with FIRST TPI intake and AFR heads. I keep going back and forth between 180's and 195's. Either would work fine but I like the 180's more and here is why.

180cc volume is better suited to a 350 with TPI intake where rpm's are lower than 5,500. They would allow for good intake velocity which would translate into quick throttle response and torque. The exhaust/intake ratio is fantastic at 80% for 0.5" lift. 180's still flow great and have been used on big cube engine like 400's with good performance.

195's are jack of all trades for 350's & 383's. They support more flow at only the higher lifts. They seem more favored for higher rpm intakes such as holley steath ram on 383's. Even with the 15cc larger volume, people haven't noticed any loss of power or throttle response. Would be worth it if think of upgrading to 383 in future.

I don't believe your ZZ4 cam with 1.6 rr's generate much lift over 0.5" to make 195's worthwhile.

johnny89345

with my cam and rr ill have .570 .570 def not small. and im trying to get the numbers on the pistons to tell what exactly they are. i ordered this snake camer from ridgid hopefully it works

burnout88

I think the GM fast burn or a ported set of vortecs would be a better choice. Just my The overall design on the fastburns are outstanding.

Blackdog36

iTrader: (3)

Vortec bowties are good but you would need a new manifold base to fit ($200). Fast burns look promising at $300-$400 less than AFR's. I still like AFR's for their high exhaust flow #'s. They also flow a little more at low lifts. Even a good ported TPI setup probably will not flow as much as fast burns can provide. Guess it will come down to price.

Johnny how are you getting .570/.570 lift numbers? I believe ZZ409 has .520/.520 with 1.5rr's. It would go up to .555/.555 with 1.6rr's.

doc

I vote for the AFR 195s. I think that they are the best cyl head on the market.