Compression Ratio Calculation

E

EPA Violator

CR Wrencher
Joined
Mar 8, 2008
Messages
560
When calculating CR, with our heads do you assume zero combustion chamber volume in the head? All the burn takes place in the piston bowl and the head is flat so I figured that would be the case. Jay
 
Nope, you do have to take in account the cc's of the valves as they are below deck height.
 
Well, working with 983 cc cylinder volume for stock common rail with average piston protrusion and 17.2:1 CR I came up with 60.7 cc of clearance volume.

So, Glenn, I would use about 40 cc for piston bowl volume and what about is the cc of the valves? Trying to work the math backward.
 
Depends on how deep the valves sit in the seats. But on average figure 6cc
 
So Glenn what is a good number to use for the combustion chamber including valve volume? I mean just the head portion, not taking into account headgasket volume.
 
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