Patriot Performance CNC Ported 5.3 2.02"/1.57" 63cc 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. Custom designed runners flow up to 60 cfm over stock OEM versions. The 63cc chambers will increase the compression on a stock LS1 from 10-1 to 10.8-1. Based on other modifications, gains of up to 40 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

Part Number:  198-2027

Technical Specs:

Combustion Chamber: 63cc
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