I just did a compression check yesterday and I was wondering if there is any way to take those numbers and find out what your compression ratio is. My numbers were 225/230/227/229. I realize you can do it with bore,stroke,head cc's, gasket thickness, deck height, #of cylinders etc. But is there any way to use the numbers from a comp. test.


[Modified by stretracr, 7:20 AM 4/19/2002]

 

pv=RT

 

pV=nRT

you forgot the number of moles

 

http://www.c-speedracing.com/howto/c.../compcalc.html

This is a compression ratio calculator. It does not use the results of a compression test but it uses the block/piston/gasket... combination to give you your CR.

You have similar compression numbers them me and I am theoritically running 11.4:1 ratio (just to give you a reference).


Edit: Ooops I did not read the last part of your first post I am not helping you at all...


[Modified by JPP, 11:26 AM 5/7/2002]

 

NOPE, doesnt work like that.

a brand new stock block can have 240psi ...

Greg

 

That is correct. A compression ratio is basically the ratio between the volume of air when the piston is at BDC and at TDC. But a compression test depend on the seal of the piston rings, the pressure of the air when the piston is at BDC (if you are running a turbo, the results of the comp. test wont be the same even if you have the same CR), the temperature of the air...
As I mention above, I am running 11.4:1 CR and yet the highest pressure I see is 230 PSI (which below the pressure seen on a blue printed, stock CR engine).

 

small v is specfic volume, which is m^3/kg, and R is in units o mass and equals
_
R divided by M, the molar mass of the gas in question

if you use big V like you did, you need the 'n',

_
and R has to have a bar over it (R) to signify molar units.


as you can tell i have had to much thermodynamics this semester