Compression ratio calculators??

[Dave Casey]

13.54 to 1

I look at as the volume with the piston at bdc divided by the volume with the piston at tdc

convert all values to cc's is easiest for me

16.387 cc's per cu inch

bore and stroke volume + deck volume + chamber volume +gasket volume-dome volume
divided by
deck volume + gasket volume + chamber volume - dome volume

[art leong]

Originally Posted by Dave Casey

13.54 to 1

I look at as the volume with the piston at bdc divided by the volume with the piston at tdc

convert all values to cc's is easiest for me

16.387 cc's per cu inch

bore and stroke volume + deck volume + chamber volume +gasket volume-dome volume
divided by
deck volume + gasket volume + chamber volume - dome volume

Thats the way i thought it was calculated. But why are the calculators on line so far off? It seems like simple math to me. I just wasn't sure of the formula.

[Adger Smith]

In doing a little number movement with most of the on line calculators I think they are not figuring the dome vol. + or - properly in the formulas.
Art,
Daves formula was the one I had at the shop that I said I would PM to you.

[NORMAN BARNARD]

Mine also converts everything to cc's so i can do a "pour check" with a burette thru the spark plug hole as a double check before the motor is sealed. At least we've found some consistency in a couple of programs.... Everybody have a good thanksgiving.

I have a compression ratio calculator on my website that seems to be very accurate. www.racingenginetechnologies.com/services
Please let me know what you think.

Thanks,

Chris Hardy

[Dave Gantz]

A couple of the ones that I tried consider piston dome as a positve number, some consider it a negative number.

[art leong]

Originally Posted by Dave Gantz

A couple of the ones that I tried consider piston dome as a positve number, some consider it a negative number.

Yes but even when entered correctly they vary by a lot. The one thing I have figured out is my new motor has about 1 more in the compression ratio.