hp_performanceparts

Will Patriot Performance Stage III Heads fit on my c5 Z06?
Intake Valve- 2.08
Exhaust Valve- 1.60
64cc Chambers


Should I go with their Stage II Heads?
Intake Valve- 2.02
Exhaust Valve- 1.57
64cc Chambers

Which would make more power thru out the power band? HP/TQ

zeevette

What's the difference, other than valve size between the two? If one has too large of ports, it'll hurt throttle response, and mid range torque, in favor of top end flow.

hp_performanceparts

Well the bigger head valves flow over 320cfm at .600 lift and the other is around 315cfm.

I was really just wondering if the 2.08/1.60 is to big for my 5.7.

My cam specs are 231/243 .617.623 118+4

I really want to maximize TQ

zeevette

If maximizing TQ is your primary goal, I'd recommend the smaller port Stg.ll, and make sure and get them milled so your CR is at least 11:1. This'll be around 59cc chambers. It's great for TQ, and will even increase your mileage. Don't forget to check your PTV.

ctusser

You have some bad cam specs if you want to maximize torque. You have a high duration and LSA which both move the torque curve up in the RPM range. I'd go with the stage 2 heads regardless.

hp_performanceparts

Yea the cam is spec'd out for a blower, when I do install one. which will be after the heads

zeevette

Well, that changes everything. Would have been nice to know about the blower at the start.

AU N EGL

Do not blow cams work best with smaller head ports for great air velocity vs larger head ports and air volume ?

hp_performanceparts

^^^True. I was going to have my 243's cnc'd saves me money and its about the same performance as the exotic heads...

ctusser

aftermarket heads become less of a performance factor when forced induction is involved, in fact you will probably be wasting money getting yours ported when you can probably boost the car beyond it's ability to handle the power with just the stock heads..