compression ratio to psi

[MrJslade]

Does anyone know how to convert compression ratio to psi. I think you just multiply your compression ratio by atmospheris pressure (14.7). Is that right?
Thanks
Jslade

 

[MrJslade]

Nope thats rong because a blaster has a 6.8:1 compression ratio and 140-150psi compression. Does anybody know what the deal is.
Thanks
jslade

 

[xJust_Causex]

I thought the blaster ran 120-130 psi?

 

[mopar1rules]

Nope thats rong because a blaster has a 6.8:1 compression ratio and 140-150psi compression. Does anybody know what the deal is.
Thanks
jslade

6.8:1 is the CCR (corrected compression ratio) or trapped compression ratio and what your trying to figure out, is probably going to need to use the UCCR compression ratio for formula, which is probably around 11.5:1 to 12:1 tops. i don't know of any formulas. sorry, i just use my TSR to have it give me an estimated psi gauge reading, for a specific UCCR and/or CCR.

 

[mopar1rules]

I thought the blaster ran 120-130 psi?

depends on the base gasket used, head gasket used, bore, ring end gap, etc. many factors can dictate that psi reading.

 

[motoman9911]

The compression ratio is the the area of the combustion chamber at bottom over the area of the combustion chamber at the top. Figuring psi from compression ratio isn't correct. The calculators you can find on the internet just give you a ball park estimate because there are too many factors that play into psi like mopar1rules stated.