I realize the 4032 is 11-13.5% Si content, where the 2618 is only .25%, meaning the 4032 resists thermal expansion better and is less prone to scuffing cylinder bores. The 2618 however is roughly 15% stronger, but tends to scuff and expand more. What to get?
CP, ACL, TOMEI, TODA, JE, etc. are of the 2618 variety
Supertech, and by request all others, 4032 variety
Does it really matter? I hear the stronger alloy needs to be re-ringed a lot more often. What would you guys recommend?
EDIT: I am talking about pistons.
SAE 4032 or SAE 2618?
Re: SAE 4032 or SAE 2618? (r34 gtr)
All those piston are good for 100hp+ by cylinder anyway.
You are talking about the silicon in forged aluminum piston right ?
First:
forged piston often have much less silicon content than cast pistons and expand more when heated than cast pistons. This requires slightly larger piston to cylinder wall clearances (0.005" instead of 0.001", for example) and oil consumption and blow-by may be higher with forged than with cast pistons. The higher clearance can also cause forged pistons to be a bit noisier than cast pistons until they warm up.
two common alloys used in forged pistons, 4032 and 2618. higher Silicon aluminum alloys such as 4032, have great wear characteristics because the silicon particulate hardens the alloy and reduces the thermal expansion. However, silicon aluminum alloys can turn brittle and become prone to fracturing when subjected to extreme stress. With a piston made of a silicon alloy once a crack starts, it doesn't stop until the piston suffers a catastrophic failure. Lower silicon alloys, such as 2618, may wear a bit faster but provide better strength and durability. In the rare case of a crack in a 2618 piston, the crack will migrate to an area of lower stress and stop. 2618 alloy pistons keep their shape under extreme pressures and high RPM's.
so 4032 is from harder material but less resistant to detonation and stress
2618 is the one to go since ca18 are not low torque monster ...
You are talking about the silicon in forged aluminum piston right ?
First:
forged piston often have much less silicon content than cast pistons and expand more when heated than cast pistons. This requires slightly larger piston to cylinder wall clearances (0.005" instead of 0.001", for example) and oil consumption and blow-by may be higher with forged than with cast pistons. The higher clearance can also cause forged pistons to be a bit noisier than cast pistons until they warm up.
two common alloys used in forged pistons, 4032 and 2618. higher Silicon aluminum alloys such as 4032, have great wear characteristics because the silicon particulate hardens the alloy and reduces the thermal expansion. However, silicon aluminum alloys can turn brittle and become prone to fracturing when subjected to extreme stress. With a piston made of a silicon alloy once a crack starts, it doesn't stop until the piston suffers a catastrophic failure. Lower silicon alloys, such as 2618, may wear a bit faster but provide better strength and durability. In the rare case of a crack in a 2618 piston, the crack will migrate to an area of lower stress and stop. 2618 alloy pistons keep their shape under extreme pressures and high RPM's.
so 4032 is from harder material but less resistant to detonation and stress
2618 is the one to go since ca18 are not low torque monster ...
Re: (r34 gtr)
i think most here will not see any difference between both alloy piston.
we are not building f1 engine.
we are not building f1 engine.
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float_6969
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I use CP pistons, which are of the 4032 variety. They do make some noise when the motor is cold, but it stops shortly after it warms ups. I just make sure and let the car idle for a couple of min before I drive it anywhere and I still have great compression and power with over 30K miles on the rebuild.