Piston Alloy Comparison
4032 2618
High silicon No silicon
Low expansion High expansion
Tighter piston-to-wall clearance More Piston-to-wall clearance needed
Quiet Operation Noise when cold
Less ductile More ductile
More stable & consistent Higher resistance to detonation
Longer life cycle Shorter life cycles
Harder Softer
2618 is a low-silicon, high-expansion alloy that is used for extreme-duty racing applications such as NASCAR, ALMS, etc. Due to its high-expansion characteristic, this alloy is engineered with additional piston to bore clearance. At the start of a cold engine, the pistons expanding process can be heard and is commonly referred to as the "piston slap". Once the engine warms up the noise subsides as the piston expands to its running clearance. 2618 is a more ductile alloy and grants higher tolerances with higher resistance to detonation. The forgiving characteristics allow for the most extreme conditions, but longevity is eventually negotiated after countless heat cycles.
4032 is a high-silicon, low-expansion alloy. Pistons made from this alloy can be installed with tighter piston to bore clearance, resulting in a tighter seal with less noise. 4032 is a more stable alloy, so it will retain characteristics such as ring groove integrity, for longer life cycle applications. Relative to 2618, 4032 is a less ductile alloy, making it less forgiving when used with boosted and/or nitrous applications.
4032 2618
High silicon No silicon
Low expansion High expansion
Tighter piston-to-wall clearance More Piston-to-wall clearance needed
Quiet Operation Noise when cold
Less ductile More ductile
More stable & consistent Higher resistance to detonation
Longer life cycle Shorter life cycles
Harder Softer
2618 is a low-silicon, high-expansion alloy that is used for extreme-duty racing applications such as NASCAR, ALMS, etc. Due to its high-expansion characteristic, this alloy is engineered with additional piston to bore clearance. At the start of a cold engine, the pistons expanding process can be heard and is commonly referred to as the "piston slap". Once the engine warms up the noise subsides as the piston expands to its running clearance. 2618 is a more ductile alloy and grants higher tolerances with higher resistance to detonation. The forgiving characteristics allow for the most extreme conditions, but longevity is eventually negotiated after countless heat cycles.
4032 is a high-silicon, low-expansion alloy. Pistons made from this alloy can be installed with tighter piston to bore clearance, resulting in a tighter seal with less noise. 4032 is a more stable alloy, so it will retain characteristics such as ring groove integrity, for longer life cycle applications. Relative to 2618, 4032 is a less ductile alloy, making it less forgiving when used with boosted and/or nitrous applications.
