Mangum Racing 267cc LS3 Cylinder Heads
These Mangum Racing 267cc LS3 heads use a 6-bolt casting with increased deck thickness while retaining the OEM 15° valve angle and LS3 valve spacing. A 267cc CNC intake runner and 96cc exhaust port provide strong mid-lift response and stable high-lift flow for serious stock-geometry naturally aspirated and boosted combinations.
Key Features
- 6-bolt Mangum Racing LS3 casting with increased deck thickness
- 15° valve angle with OEM LS3 valve spacing
- 267cc CNC intake ports, 96cc exhaust ports, and 68.5cc CNC chambers
- 2.165" hollow-stem stainless intake valves and 1.600" hollow-stem stainless exhaust valves
- Bronze guides, PAC .660" dual springs, titanium retainers, Viton seals, and 1.250" steel spring seats
- Chamber softening available for 4.000", 4.065", and 4.125" bores; minimum bore 4.000"
Airflow Performance
SuperFlow data with a 4.125" bore plate; intake uses a radius entry and exhaust is tested without a pipe.
| Valve Lift | .200 | .300 | .400 | .500 | .600 | .700 |
|---|---|---|---|---|---|---|
| Intake CFM | 148 | 227 | 282 | 325 | 350 | 363 |
| Exhaust CFM | 114 | 164 | 200 | 233 | 240 | 243 |
Installation note: Verify pushrod length after selecting the camshaft, gasket thickness, and final chamber size.
Processing & Shipping Overview
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