Trick Flow engineers combined the best features of factory GM LS3 and LS7 cylinder heads with Trick Flow’s own unique brand of race-winning engineering and technology to create the ultimate square port LS cylinder head for 4.000″ and larger bore engines—the GenX® 255. The heads feature fully CNC Competition Ported runners with a premium high resolution surface finish for maximum airflow and performance potential. The valve angles have been changed from 15° to 12° to increase piston-to-valve clearance and allow the use of larger camshafts. The coolant holes through the head deck were redesigned to work with all LS head gasket and engine block combinations. Stock LS3 ports accommodate LS3-style intake manifolds and LS9/LSA blower assemblies. GenX 255 heads are available with standard and 6-bolt per cylinder mounting patterns. Trick Flow GenX 255 cylinder heads are emissions-legal under CARB E.O. #D-747 for 2007-present GM vehicles with 6.2L engines. They are available fully assembled or as bare castings. Sold individually. **SHIPS DIRECT FROM MANUFACTURER – SUBJECT TO DELAYS** Cylinder Head Style: Assembled Cylinder Head Material: Aluminum Intake Port Shape: Rectangular Intake Valve Diameter (in): 2.165 in. Cylinder Head Finish: Natural Combustion Chamber Volume (cc): 69 CNC-Machined Combustion Chamber: Yes Intake Runner Volume (cc): 255cc Exhaust Runner Volume (cc): 87cc CNC-Machined Intake Runner: Yes CNC-Machined Exhaust Runner: Yes Combustion Chamber Style: Heart Intake Port Location: Standard Exhaust Port Shape: Oval Exhaust Port Location: Standard Spark Plug Style: Angle Intake Valves Included: Yes Exhaust Valves Included: Yes Exhaust Valve Diameter (in): 1.600 in. Valve Springs Included: Yes Maximum Valve Lift (in): 0.650 in. Outside Diameter of Outer Spring (in): 1.300 in. Damper Spring Included: No Number of Springs Per Valve: Dual Retainers Included: Yes Retainer Material: Titanium Locks Included: Yes Lock Style: 7 degree Valve Stem Seals Included: Yes Rocker Arm Studs Included: No Rocker Arms Included: No Rocker Arm Nuts Included: No Guideplates Included: No Accessory Bolt Holes Drilled: Yes Intake Valve Angle: 12 Exhaust Valve Angle: 12 Valve Guides Included: Yes Valve Guide Material: Powdered metal Valve Seats Machined: Yes Valve Seat Machine Style: 3-angle Valve Seat Material: Ductile iron Steam Holes Drilled: No Oiling Style: Through pushrod Machined for O-Ring: No Heat Crossover: No Quantity: Sold individually. Notes: These cylinder heads can only be used with a minimum bore diameter of 4.000 in. Includes new rocker arm rail mounts for use with LS3 1.7 ratio rocker arms. OEM rocker arm rail mounts will not work with these heads. CARB EO Number: D-747-1 (pdf) To see a list of qualifying vehicles, enter CARB EO Number D-747-1 Emissions: California EO Approved
