Bushed Pistons – Strength, Efficiency & Development | CP-Carrillo

What is a Bushed Piston?

Our bushed piston design takes reliability to the next level. By incorporating a precision shrink-fit bushing inside the pin bore, we isolate the high-load, high-friction contact between the pin and bore from areas exposed to tensile stress. Installed with interference, the bushing remains under compression—delivering added strength, stability, and long-lasting performance.

Key Advantages

  1. Higher Maximum Contact Pressure
  • Aluminum alloys (2618/4032): ~100 MPa (N/mm²)
  • High strength Copper Alloy bushing: ~300 MPa (N/mm²)

This allows:

  • a more robust solution (higher mileage, higher safety factors).
  • In addition, if optimized with smaller pin bore diameter and shorter pin, performance advantages can be expected through reduction of friction losses. 
  • Increased horsepower in an existing engine without changing compression height or pin diameter (assuming pin strength is sufficient).
  • Option to maintain compression height while reducing pin diameter, which also reduces piston crown stress.

Note: Actual durability depends on other parameters including lubrication, temperature, pin coatings, and pin deformation (bending, ovalization).

  1. Higher Young’s Modulus (Stiffness)
  • 2618 aluminum: 74 GPa
  • 4032 aluminum: 81 GPa
  • Copper Alloy bushing: 131 GPa

The bushing material’s modulus is ~70% higher than the aluminum piston material. This reduces pin bore deformation (ovalization), which in turn lowers friction losses and improves efficiency.

Material Note: Copper Alloy bushing is a proprietary high-strength copper alloy specifically engineered for this application.

Real-World Development Story

A high-level motorsports customer requested a short-life engine package targeting half the durability (vs. the standard) but with higher output.

  • Piston pin diameter reduced: 20mm → 17mm
  • Pin weight reduced: 85g → 70g 
  • Small-end rod weight reduced: 15g
  • Result: +2 HP on the dyno (seemingly small, but highly valuable in top-level racing)
  • Outcome: important race victories followed. Engine was then dyno-tested and finished to standard durability testing without failure.

From this point forward, the bushed piston package became a standard race component—delivering higher performance and improved durability.