compression

It depends on some factors with regard to ring sealing (blow by) and your dynamic compression not static, which can be quite different especially for a cam with any overlap.

On a new tight engine assuming ideal gas behavior you can expect pressure to equal Dynamic CR to power 1.3 at sea level e.g. for 9.5:1 dynamic CR it would be 18.7 Bara (absolute) or 17.7 Barg (gauge).

Julian
17.7 bar = 256.716729 psi

18.7 bar = 271.220499 psi

i don't understand how these seemingly arbitrary bar figures relate with no knowledge of when the intake valve closes and the actual dynamic compression stroke begins?

256.x & 271.x psi are a good 100 psi over normal cranking cylinder psi findings
quote:
Originally posted by 4V & Proud:
17.7 bar = 256.716729 psi

18.7 bar = 271.220499 psi

i don't understand how these seemingly arbitrary bar figures relate with no knowledge of when the intake valve closes and the actual dynamic compression stroke begins?

256.x & 271.x psi are a good 100 psi over normal cranking cylinder psi findings


Correct I don't know the cam specs from Rene's information, nor any other internal losses (rings sealing) I simply posted an example of an ideal theoretical calculation if his dynamic compression was 9.5:1.

A leak down test provides for far more meaningful information.

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