B58 Billet Main Caps by 5150 AutoSport

5150 AutoSport B58 Billet Main Caps

As power levels climb beyond 1,200+ horsepower, we've seen factory main caps begin to walk. Under extreme cylinder pressure and crankshaft loads, even the slightest cap movement can affect main bearing alignment, oil clearance, and ultimately bearing life.

Our CNC-machined billet steel main caps are heat treated for maximum strength and feature a dowel-pinned design to positively locate each cap and virtually eliminate cap movement under extreme loads.

Benefits of our Billet Main Caps:

• CNC-machined from high-strength billet steel.
• Heat treated for maximum durability and strength.
• Dowel-pinned design for precise cap location and reduced cap walk.
• Increased rigidity over OEM cast main caps.
• Reduced main cap flex under extreme cylinder pressure.
• Minimized crankshaft movement under high load.
• More consistent main bearing bore geometry.
• Improved crankshaft stability at high RPM and boost.
• Better bearing life and oil clearance consistency.
• A much stronger foundation for high-horsepower engine builds.

When you're pushing an engine to its limits, every thousandth of an inch matters. Our billet, heat-treated, dowel-pinned main caps help keep the crankshaft exactly where it belongs, providing the bottom end with the stability needed to survive extreme horsepower and high-RPM abuse.

Important: Billet main caps are not a simple bolt-on upgrade. The engine block and main caps must be precision machined, followed by align boring and align honing, to restore perfect main bearing geometry and ensure proper bearing clearances.