Chevrolet C6 Corvette LS -LS3-LS7

Mangum Racing 273cc Qualcast LS7 Cylinder Heads

Mangum Racing CNC Ported 273 LS7 Cylinder Heads

Built from the Qualcast stock style replacement LS7 casting, the Mangum Racing 273 program is designed for high-rpm, large-displacement LS combinations that demand elite airflow and structural integrity.

Featuring a 12° valve angle and OEM LS7 valve spacing/valve length, this 6-bolt casting delivers exceptional port efficiency while maintaining compatibility with LS7-based platforms. With a 273cc CNC intake runner and optimized 93cc exhaust port, this cylinder head is engineered for serious naturally aspirated builds and high-output boosted applications where the customer wants a near bolt on cylinder head.

Each set is fully CNC machined in-house on our Centroid 5-axis machining centers and finished on Newen seat and guide equipment. Every head is hand blended, assembled, and inspected in small batches to ensure dimensional accuracy and repeatable performance.

Airflow Performance

Tested on a SuperFlow 1020 with a 4.125” bore plate

Intake (Radius Entry)

• .200” – 160 CFM
• .300” – 255 CFM
• .400” – 311 CFM
• .500” – 352 CFM
• .600” – 380 CFM
• .700” – 390 CFM

Exhaust (No Pipe)

• .200” – 117 CFM
• .300” – 160 CFM
• .400” – 209 CFM
• .500” – 221 CFM
• .600” – 230 CFM
• .700” – 244 CFM

The 273 LS7 delivers outstanding mid-lift efficiency with dominant high-lift airflow, making it ideal for aggressive street / strip combinations.

Premium Hardware & Construction

• 6-bolt Qualcast LS7 casting
• 12° valve angle with OEM LS7 valve spacing
• Stock Valve Lengths
• 273cc CNC intake port
• 93cc exhaust port
• 70.5cc CNC combustion chambers (milling available at no charge)
• 2.200” titanium intake valves
• 1.610” stainless exhaust valves
• Bronze CHE guides
• PAC .660” dual spring package
• Titanium retainers
• Viton seals
• 1.250” steel spring seats
• Chamber softening available
• Flat milling at .006” per cc
• Minimum bore: 4.100”

Designed for LS7 Street & Strip Builds

With airflow over 390 CFM at .700” lift, the Mangum Racing 273 LS7 is capable of supporting serious naturally aspirated horsepower in 427+ cubic inch combinations.

Stock pushrod length works in many applications but should always be verified based on camshaft selection and final milling.

Mangum Racing 267cc LS3 Cylinder Heads

Mangum Racing CNC Ported MR 15° LS3 Cylinder Heads

Built from our 6-bolt 15° LS3 casting featuring increased deck thickness, the MR 15° LS3 is engineered for serious naturally aspirated and boosted combinations that demand airflow, strength, and repeatability — while maintaining OEM valve angle and valve location geometry.

This casting is designed to support 1,500+ horsepower combinations when paired with the proper short block and induction system, making it an ideal solution for builders who need maximum performance without moving away from stock valve layout.

Each set is fully CNC ported in-house on new Centroid 5-axis machining centers and finished on Newen seat and guide equipment. Every cylinder head is hand blended, inspected, and assembled in small batches to ensure dimensional accuracy and consistency.

Airflow Performance

Tested on a SuperFlow bench with a 4.125” bore plate

Intake (Radius Entry)

• .200” – 148 CFM
• .300” – 227 CFM
• .400” – 282 CFM
• .500” – 325 CFM
• .600” – 350 CFM
• .700” – 363 CFM

Exhaust (No Pipe)

• .200” – 114 CFM
• .300” – 164 CFM
• .400” – 200 CFM
• .500” – 233 CFM
• .600” – 240 CFM
• .700” – 243 CFM

With a 267cc CNC intake runner and optimized 96cc exhaust port, the MR 15° delivers strong mid-lift efficiency and stable high-lift airflow — ideal for aggressive hydraulic roller and race-oriented camshaft profiles while retaining factory valve geometry.

Premium Hardware & Construction

• 6-bolt Mangum Racing LS3 casting with increased deck thickness
• 15° valve angle with OEM LS3 valve spacing
• 2.165” hollow stem stainless intake valves
• 1.600” hollow stem stainless exhaust valves
• Bronze guides
• PAC .660” dual spring package
• Titanium retainers
• Viton seals
• 1.250” steel spring seats
• 68.5cc CNC chambers (milling available at no charge)
• Chamber softening options for 4.000”, 4.065”, and 4.125” bore sizes
• Flat milling at .006” per cc
• Minimum bore: 4.000”

Built for High-Output Stock-Geometry Combinations

The increased deck thickness provides added durability under elevated cylinder pressure, while the 15° valve angle maintains compatibility with stock-style piston valve reliefs and factory-based valvetrain geometry.

The PAC .660” dual spring system offers the stability required for serious street or race camshaft profiles, and stock pushrod length works in many applications (final length should always be verified based on camshaft and milling).

For builders who need to retain OEM valve angles and locations but demand serious airflow capability, the MR 15° LS3 casting delivers.