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| HEAD FLOW COMPARISON | | The heads were compared on a JK&M Custom Flow 400-cfm flowbench. Testing was performed at 28 inches of water. | | 6X Iron Head | KRE Aluminum Head | | Lift | Intake | Exhaust | Intake | Exhaust | | .100 | 88 | 85 | 92 | 71 | | .200 | 153 | 122 | 166 | 129 | | .300 | 206 | 164 | 234 | 169 | | .400 | 221 | 185 | 256 | 201 | | .500 | 232 | 196 | 261 | 220 | | DYNO TESTING | | The heads were tested on a 455 (now 468) engine mounted on a Super Flow SF-901 dynamometer. Jeff usually does not acknowledge the torque figure at the start of the pull because it could be incorrect. So the reading was taken at 3,900 to get a more realistic number on the 6X head pull. The correction factor for testing was 1.083. | | BEST PULL: 6X HEADS WITH Q-JET | | RPM | CORRECTED TORQUE | CORRECTED HP | | 3,500 | 524.5 | 349.5 | | 3,600 | 514.4 | 352.6 | | 3,700 | 518.4 | 365.2 | | 3,800 | 521.3 | 377.1 | | | 3,900 | 522.0 | 387.6 | | 4,000 | 521.2 | 397.0 | | 4,100 | 517.2 | 404.0 | | 4,200 | 502.2 | 401.6 | | 4,300 | 495.9 | 406.0 | | 4,400 | 504.7 | 422.8 | | 4,500 | 509.0 | 436.1 | | 4,600 | 506.0 | 443.2 | | 4,700 | 497.6 | 445.3 | | 4,800 | 494.3 | 451.7 | | 4,900 | 486.4 | 453.8 | | 5,000 | 471.4 | 448.8 | | 5,100 | 457.7 | 444.4 | | 5,200 | 455.8 | 451.3 | | 5,300 | 451.2 | 455.4 | | 5,400 | 439.2 | 451.5 | | 5,500 | 427.1 | 447.2 | | BEST PULL: KAUFFMAN ALUMINUNM HEADS WITH Q-JET | | RPM | CORRECTED | CORRECTED | | TORQUE | HP | | 3,500 | 547.2 | 364.6 | | 3,600 | 549.5 | 376.7 | | 3,700 | 548.1 | 386.2 | | 3,800 | 548.4 | 396.8 | | 3,900 | 548.6 | 407.4 | | 4,000 | 548.3 | 417.6 | | 4,100 | 546.3 | 426.4 | | 4,200 | 545.9 | 436.6 | | 4,300 | 543.4 | 444.9 | | 4,400 | 539.4 | 451.9 | | 4,500 | 537.4 | 460.4 | | 4,600 | 534.9 | 468.5 | | 4,700 | 532.5 | 476.5 | | 4,800 | 523.5 | 478.5 | | 4,900 | 518.9 | 484.1 | | 5,000 | 511.4 | 486.9 | | 5,100 | 501.6 | 487.1 | | 5,200 | 492.7 | 487.8 | | 5,300 | 485.4 | 489.8 | | 5,400 | 478.1 | 491.6 | | 5,500 | 471.9 | 494.2 | | 5,600 | 463.6 | 494.3 | ABOUT THE DYNO ENGINE
Block: .060-over 455 = 468 ci
Crank: Stock nodular iron, 4.21 stroke, rotating assembly balanced
Rods: Crower forged steel, stock 6.625 length
Oiling System: Stock
Pistons: TRW forged, flat-top, exactly-zero deck
Compression Ratio: 9.95:1
Heads: 6X, 2.11/1.77 valves
Mods: Port-matched, cleaned up, bowl work, bigger exhaust valves
Valve Job: Custom, multi angles
Chamber Size: 91 ccs
Head Gasket: Fel-Pro 8518
Rocker Arms: Crane, 1.65:1 roller, Rhoads lifters
Cam: Crower PN 60919, hydraulic
Duration at .050: 231/240
Lift: .517/.517 with 1.65:1 rockers
Lobe Separation Angle: 113
Installed Position: Intake set at 109 centerline
Intake Manifold: OEM '68 cast iron
Mods: Reworked at carb flange to fit both bolt patterns, Q-jet and Holley
Carb: Q-jet, .073 primary jets, .048 custom-machined secondary rods
Carb: Holley, custom .093 primary jets, custom .097 secondary jets
Distributor: GM HEI, 20 mechanical advance
Timing: 30 total, all in by 2,500 rpm
Spark Plugs: AC R45TSX
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