Patriot Performance CNC Ported Perimeter Bolt 2.02"/1.57" 67cc Heads Assembled

Our custom 5 axis CNC machined new GM castings make these heads a must have for any performance oriented GM LS series engine. These heads provide are specifically for 97-98 LS applications. Custom designed runners flow up to 60 cfm over stock OEM versions.Based on other modifications, gains of up to 30 rwhp can be expected. These are a great choice for naturally aspirated engines and applications where 75-150hp nitrous systems will be used. The Stage II heads feature 21-4N 2.02"/1.57" stainless steel valves, our Original Patriot Gold Dual .650" Lift springs, titanium retainers, Super 7 machined locks, custom honed bronze guides, machined spring bases, and viton rubber seals.

*Sold as Pair

Technical Specs:

Combustion Chamber: 67cc
Intake Runner: 220cc
Exhaust Runner: 67cc
Intake Valve: 2.02"
Exhaust Valve: 1.57"
Max. Valve Spring Lift: 0.650"
Spring Pressure Closed: 135 lbs. @ 1.800"
Spring Pressure Open: 375 lbs. @ 1.090"
Retainer Material: Titanium
Valve Seal Material: Viton
Valve Guide Material: Manganese Bronze
Valve Job: 5-angle