B46 Combustion Chamber Upgrade Service

Please note that pricing is based on the customer providing a core. If you need assistance sourcing a core, contact our sales team.

For enthusiasts and builders pushing the limits of BMW’s B46 engine, optimizing the combustion chamber is a critical step toward maximizing performance and reliability. The 5150 Combustion Chamber Upgrade Service reshapes the combustion chambers using state-of-the-art 5-axis CNC equipment for improved flow, consistency, and combustion efficiency—delivering proven gains in power, torque, and responsiveness.

All machining is performed on our Rottler 5-Axis CNC platform to ensure precise, repeatable results across all cylinders. This service is ideal for customers integrating performance upgrades such as forged pistons, aftermarket turbos, or high-lift camshafts, ensuring the combustion chamber no longer remains a limiting factor.

CNC Combustion Chamber Reshaping Process for B46 Heads

1. 3D Scanning and Digital Modeling
Each combustion chamber is digitally scanned and converted into a 3D model. This detailed map reveals flow inefficiencies, shrouded areas, and opportunities for reshaping.

2. Chamber Optimization
Our engineering team refines the combustion chamber geometry to improve airflow and fuel atomization while reducing hot spots and detonation risk—critical for both high-boost and high-revving applications.

3. 5-Axis CNC Machining
The redesigned chamber shape is cut using our Rottler EM69HP CNC system, ensuring that every chamber is identical in volume, shape, and surface finish. Precision surface smoothing enhances both airflow and combustion.

4. Final Inspection
Each head undergoes a rigorous dimensional check and, if requested, flow-bench testing. We verify uniformity and tolerances to ensure consistent, reliable results across all four cylinders.

Performance Benefits for the B46 Platform

• Power and Torque Gains
  Redesigned chambers improve cylinder filling and combustion pressure, delivering measurable increases in horsepower and torque—especially when paired with supporting mods like big turbos or upgraded fueling.
• Improved Combustion and Knock Resistance
  Refined shaping helps promote even flame travel, reduces detonation risk under boost, and supports more aggressive ignition timing and higher compression ratios.
• Balanced Performance Across Cylinders
  CNC repeatability ensures that no cylinder runs hotter or leaner than the rest—an essential factor for high-stress, high-RPM builds.
• Compliments Other Performance Upgrades
  This upgrade enhances the effectiveness of aftermarket camshafts, valves, porting, forced induction, and exhaust systems by allowing the combustion chamber to flow and burn as efficiently as the rest of the engine components.