Some parts are not legal for sale or use in California or other states with similar laws/regulations—see pg. 2 for details. WARNING: For Proposition 65 information, see pg. 2 GenX® 255, 255HD, and 280 HD Square Port Cylinder Heads for GM LS3 Specifi cations Material: A356-T61 aluminum Combustion Chamber Volume: CH1/CH2: 67cc CNC-profi led C01: 69cc CNC-profi led Intake Port Volume: 255cc CNC Competition Ported Intake Port Location: Stock LS3 Intake Port Dimensions: 2.550" x 1.250" LS3 square port Intake Gaskets: GM LS3/L92 Intake Valve Diameter: C01: 2.165" (TFS-32600211) CH1/CH2: 2.165" (TFS-32600214) Intake Valve Seat: Ductile iron (TFS-51600271-1) Exhaust Port Volume: 87cc CNC Competition Ported Exhaust Port Location: Stock LS3 Exhaust Port Dimensions: 1.460" x 1.700" oval Exhaust Gaskets: GM 12558573 Exhaust Valve Diameter: C01: 1.600" (TFS-32600274) CH1/CH2: 1.600" (TFS-32600215) Exhaust Valve Seat: Ductile iron (TFS-30600274) Valve Angles: 12° Valve Guide Material: Trick-Alloy powdered metal (TFS-30700252) Valve Seals: Viton® fl uoroelastomer canister (TFS-30600455) Valve Seat Angles: 45° x multi-angle Valve Spring Pocket Diameter: 1.480" Valve Spring I.D. Locators: 1.300" (TFS-21400443) Valve Spring Retainers: Steel (TFS-21400410); titanium (TFS-214T0415) Valve Stem Locks: 7° steel (TFS-30600444) Valve Springs, Standard: 1.300" o.d. dual spring (TFS-16904-16) 150 lbs. @ 1.800" installed height 400 lbs. @ 1.200" open 370 lbs. per inch rate .625" max. valve lift Valve Springs, Optional: 1.300" o.d. dual spring (TFS-16306-16) 155 lbs. @ 1.800" installed height 465 lbs. @ 1.200" open 448 lbs. per inch rate .650" max. valve lift Rocker Arms, Standard Valve Springs: OEM LS3 with upgraded bearings or roller rocker arms Rocker Arms, Optional Valve Springs: Roller rocker arms recommended Minimum Bore Diameter: 4.000" Cylinder Head Bolts/Studs: TFS-92010 (bolts) or ARP 234-4316 (studs) for pre-2004; TFS-92011 (bolts) or ARP 234-4317 (studs) for 2004 and later Head Gaskets, C01 Standard: TFS-32694100-045 or TFS-32694100-051 C01 6-Bolt: TFS-30694125L051 and TFS-30694125R051 or TFS-30694185L051 and TFS-30694185R051 Pushrod Length: Longer than stock required Spark Plugs: NGK 4177 NOTES: Assembled cylinder heads include new rocker arm rail mounts (TFS-326LS3) for use with LS3 1.7 ratio rocker arms. The OEM LS3 rocker arm rail mounts will not work with GenX 255, 255 HD, and 280 HD heads. Cylinder heads with the optional 6-bolt mounting pattern do not fi t 2010 and later Chevrolet Camaro OEM exhaust manifolds; aftermarket headers are required. Viton® is a registered trademark of DuPont Performance Elastomers. Dyno Results GenX 255 Square Port Test Engine: GM 6.2L LS3 short block with 10.43:1 compression, Trick Flow GenX® 255 square port cylinder heads (TFS-3261T002-C01), Trick Flow Track Max® hydraulic roller cam (TFS-32603001), stock L92 intake with 90mm throttle body, Kooks headers with 17⁄8" primaries, and dual exhaust with 3" Flowmaster muffl ers. GenX ® 255, 255HD, and 280 HD Square Port Cylinder Heads for GM LS3 Trick Flow engineers combined the best features of GM’s LS3 and LS7 cylinder heads to create the ultimate square port LS cylinder head—the GenX 255. The heads feature fully CNC Competition Ported square port runners with a premium high resolution surface fi nish for maximum airfl ow 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. The heavy-duty HD versions of these heads have Manley Severe Duty stainless steel intake and exhaust valves to handle the additional stress and abuse of big power adder applications. The HD heads are available with your choice of 255cc or 280cc intake ports. GenX 255 heads are emissions-legal under CARB E.O. #D-747-1 for 1997-2015 GM vehicles with 6.2L engines. Cylinder heads are available fully assembled or as bare castings. Sold individually. GenX 255 Heads, CNC Competition Ported Runners, Assembled TFS-32610001-C01 1.300" dual valve springs (370 lbs./in.), 255cc intake runners TFS-32610002-C01 1.300" dual valve springs (448 lbs./in.), 255cc intake runners TFS-3261T001-C01 1.300" dual valve springs (370 lbs./in.) and titanium retainers, 255cc intake runners TFS-3261T002-C01 1.300" dual valve springs (448 lbs./in.) and titanium retainers, 255cc intake runners TFS-3261T003-C01 1.300" dual valve springs (370 lbs./in.), titanium retainers, and 6-bolt pattern, 255cc intake runners TFS-3261T004-C01 1.300" dual valve springs (448 lbs./in.), titanium retainers, and 6-bolt pattern, 255cc intake runners GenX 255 HD Head, CNC Competition Ported Runners, Assembled TFS-3261T004-CH1 1.300" dual valve springs (448 lbs./in.), titanium retainers, and 6-bolt pattern, 255cc intake runners GenX 280 HD Head, CNC Competition Ported Runners, Assembled TFS-3261T004-CH2 1.300" dual valve springs (448 lbs./in.), titanium retainers, and 6-bolt pattern, 280cc intake runner choice of 255cc or 280cc intake ports. GenX 255 heads are emissions-legal under CARB E.O. #D-747-1 for 1997-2015 GM vehicles with 6.2L engines. Cylinder heads are available fully assembled or as bare castings. TFS-3261T004-C01 Exhaust Side Airfl ow Results GenX 280 HD Square Port Lift Value Intake Flow CFM Exhaust Flow CFM .100" 72 57 .200" 147 111 .300" 229 161 .400" 296 207 .500" 340 242 .600" 373 255 .700" 391 262 Tests conducted at 28" of water (pressure). Bore size: 4.125"; exhaust with 21⁄8" pipe. 1.300" dual valve springs (448 lbs./in.), titanium retainers, and 6-bolt pattern, 255cc intake runners GenX 280 HD Head, CNC Competition Ported Runners, Assembled 1.300" dual valve springs (448 lbs./in.), titanium retainers, and 6-bolt pattern, 280cc intake runner
