Introducing the 4P "Circuit Pro" K-Series Race Head
The 4P Race Casting has consistently delivered top-tier performance across motorsports disciplines. Proven in both All Motor and Turbo classes, it sets the benchmark with superior materials, increased rigidity, and a motorsports-focused port and chamber design. While others remain constrained by OEM castings built for economy cars, we've engineered a cylinder head specifically for high-performance racing applications
Purpose-built for the latest generation of 4P Endurance Racing Engines, the Circuit Pro lets you power your race car or performance street build with the same cutting-edge technology featured in our flagship competition engines.
Key features:
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20–28 CFM airflow increase over the Pro 156v2 head—without increasing port volume
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Optimized combustion chamber design for superior air/fuel management and efficiency
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Motorsports-grade casting, designed from the ground up—not modified from an OEM base
- 36mm Intake Valve / 30mm Exhaust Valve
The Circuit Pro is more than an upgrade—it's a platform built to dominate.
Casting Design Features
As OEM castings have gone out of production, those in the field have aged and worn, and the demands on our race engines have increased, we needed to develop a superior alternative to OEM. The 4P Race Casting is superior in every way. Exclusively available at 4P.
- Made IN THE USA from A356-T6 Aluminum
- These "porting castings" give us a clean slate to put any port size and shape we choose, and offer a "full cleanup"
- Port wall thickness is increased over OEM dramatically to allow us to run larger ports and move them around for high rpm applications. Increased port wall thickness also allows for extreme boost applications.
- Extra thick deck for increased rigidity and superior gasket sealing.
- Superior cooling through 3D printed water jackets
- All heads accept VTEC and non-VTEC arrangement with OEM or aftermarket components.
- These race ported heads are 100% designed, machined, and finished in house at 4 Piston Racing. We will build you the head you need for your race or street program.
- Heads available in PRB and RSP/RBC Style water jacket arrangements.