Need some input from those who have more sanity than I do. Looking for pistons for my m20b30 build, with an 85.8mm stroke and 86mm bore. Here are measurements between stock m20b25 and the setup I'm thinking about using.
m20b25:
Crank throw = 75
Rods = 135
Piston KH = 34.2
Total stack height from center of crank to top of piston = 206.7
m20b30 concept
Crank throw = 85.6
Rods = 130
Piston KH = 33.53
Total stack height from center of crank to top of piston = 206.33 (0.37mm lower than OEM, well within block deck height tolerance. Basically identical)
So with this new setup, I would end up with a flat top piston with same diameter wrist pin, and same size compression rings. CR would be between 9:1 and 10:1 depending on dish volume which is currently unknown, but small. The piston is cast aluminum and costs $170 for two sets of four.
Any thoughts?
m20b25:
Crank throw = 75
Rods = 135
Piston KH = 34.2
Total stack height from center of crank to top of piston = 206.7
m20b30 concept
Crank throw = 85.6
Rods = 130
Piston KH = 33.53
Total stack height from center of crank to top of piston = 206.33 (0.37mm lower than OEM, well within block deck height tolerance. Basically identical)
So with this new setup, I would end up with a flat top piston with same diameter wrist pin, and same size compression rings. CR would be between 9:1 and 10:1 depending on dish volume which is currently unknown, but small. The piston is cast aluminum and costs $170 for two sets of four.
Any thoughts?
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