Mangum Racing CNC Ported MR 15° LS Cathedral Port Cylinder Heads
Built from your choice of 4-bolt or 6-bolt 15° LS casting featuring increased deck thickness, the MR 15° LS1 is engineered for serious naturally aspirated and boosted combinations that demand airflow, strength, and repeatability, while maintaining OEM valve angle and valve location geometry.
Featuring a 2.02/1.57 valve combo the 229cc version easily clears the bores on 4.8L/5.3L engines and up! This is not a simple LS6 cylinder head copy, this is a ground up designed cylinder head with fully cnc ported ports & chambers for optimum power & performance.
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
Intake (Radius Entry)
- .200” – 138 CFM
- .300” – 207 CFM
- .400” – 260 CFM
- .500” – 293 CFM
- .600” – 315 CFM
- .700” – 321 CFM
Exhaust (No Pipe)
- .200” – 109 CFM
- .300” – 154 CFM
- .400” – 198 CFM
- .500” – 223 CFM
- .600” – 235 CFM
- .700” – 240 CFM
With a 229cc CNC intake runner and optimized 97cc exhaust port, the MR 15° delivers strong mid-lift efficiency and stable high-lift airflow, ideal smaller bore LS engines 3.780"-4.00")
Premium Hardware & Construction
- 4-bolt Mangum Racing LS1 casting with increased deck thickness
- 15° valve angle with OEM LS valve spacing
- 4 Bolt or 6 Bolt Casting Available
- 2.02” stainless intake valves
- 1.57" stainless exhaust valves
- Bronze guides
- PAC dual spring package
- Titanium retainers
- Viton seals
- 1.250” steel spring seats
- 62cc CNC chambers (milling available at no charge)
- Chamber softening options available
- Flat milling at .007” per cc
- Minimum bore: 3.780” (4.8/5.3)
- 4.030" minimum gasket bore
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 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 on a smaller bore LS engine, the MR 15° LS1 229cc casting delivers.
