PRC LS7x 265cc CNC Heads

Mangum Racing Brodix 267cc LS3 Cylinder Heads

Mangum Racing CNC Ported Brodix 15° LS3 Cylinder Heads

Built from Brodix 6-bolt LS3 castings with extra deck thickness, our Mangum Racing 15° LS3 heads are designed for serious naturally aspirated and boosted combinations that demand airflow, strength, and repeatability.

Each set is fully CNC ported in-house with brand new Centroid 5-axis CNC mills and Newen seat & guide machines. Every set of cylinder heads is hand blended and carefully inspected before final assembly to ensure dimensional accuracy and consistency.

Airflow Performance

(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, these heads deliver strong mid-lift numbers with excellent high-lift stability — making them ideal for aggressive hydraulic roller street & race builds needing to retain the stock valve locations & angles.

Premium Hardware & Construction

• 6-bolt Brodix LS3 casting with increased deck thickness
• 15° valve angle, 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
• .006” per cc flat milling available
• Minimum bore: 4.000”

Designed for Builders Who Care About the Details

These are not mass-produced heads. Each set is machined, assembled, hand blended, and inspected in small batches to maintain strict quality control and dimensional consistency.

Extra deck thickness adds durability for higher cylinder pressure combinations. The PAC .660” dual spring setup provides valvetrain stability for serious cam profiles. Stock pushrod length works in most applications but should always be verified based on camshaft and final milling.

If you’re building a combination needing to stay stock valve angles & locations then this cylinder head is hard to beat!

Mangum Racing 275cc 11° LS3 Cylinder Heads

Mangum Racing CNC Ported MR275 11° LS3 Cylinder Heads

Built from the Mangum Racing 6-bolt 11° LS3 casting featuring a massive .750” deck surface, the MR275 is designed for maximum-effort naturally aspirated and boosted LS combinations where airflow, strength, and valvetrain stability are non-negotiable.

This casting was engineered for builders who want every available advantage — valve angle, deck thickness, port efficiency, and piston-to-valve clearance — all optimized to support serious compression and high cylinder pressure environments.

Each set is fully CNC machined in-house on brand new Centroid 5-axis machining centers and finished on Newen seat & guide equipment. Every head is hand blended, inspected, and assembled in small batches to ensure repeatability and precision.

Airflow Performance

Tested on a SuperFlow bench with a 4.125” bore plate

Intake (Radius Entry)

• .200” – 143 CFM
• .300” – 221 CFM
• .400” – 283 CFM
• .500” – 330 CFM
• .600” – 358 CFM
• .700” – 381 CFM

Exhaust (No Pipe)

• .200” – 112 CFM
• .300” – 161 CFM
• .400” – 202 CFM
• .500” – 232 CFM
• .600” – 242 CFM
• .700” – 248 CFM

With a 275cc CNC intake runner and optimized 98cc exhaust port, the MR275 delivers exceptional mid-lift efficiency with dominant high-lift airflow. The 11° valve angle significantly improves piston-to-valve clearance, allowing aggressive cam timing and higher compression strategies without compromise.

Premium Hardware & Construction

• 6-bolt Mangum Racing 11° LS3 casting with .750” deck thickness
• Optimized 11° valve angle and revised valve locations
• 2.185” hollow stem stainless extended-length intake valves
• 1.600” stainless extended-length exhaust valves
• Bronze guides
• Choice of PAC 1207X, 1208X, or 1209X dual spring packages
• Titanium retainers
• Viton seals
• 1.250” steel spring seats
• 70.5cc fully 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
• Substantial piston-to-valve clearance for advanced camshaft profiles and compression increases
• Minimum bore: 4.000”

Built for Maximum Effort Combinations

The increased deck thickness supports extreme cylinder pressure in large displacement and boosted applications. The revised 11° valve angle enhances airflow efficiency while providing additional mechanical clearance — a critical advantage in high-rpm, high-lift camshaft programs, or builds where smaller combustion chambers are required.

These heads have supported combinations exceeding 2,000 horsepower and 200+ mph in competition environments, making the MR275 a proven solution for serious LS3-based builds.

If you are building a no-compromise LS3 combination — naturally aspirated or power-adder — the MR275 was designed for exactly that purpose.

• Based off PRC's CNC Ported LS7 Heads
• 2.200"/1.610" Valves (base price for exchange includes new stainless exhaust valves)
• Available with PRC Double Spring Kit Complete With PRC Double Springs, Titanium Retainers, Seats, & Seals
• Completely Assembled & Setup To Your Specs!!
• Available With Stainless, Hollow Stems, or titanium valves!