Reply to thread

Message

[QUOTE="photomd, post: 1117904, member: 72878"]
I can't post a link, but from what I remember, compression ratio is the difference between BDC and TDC. I think what's stated above is trapped compression ratio. That is the ratio of the volume just as the exhaust port is blocked to the TDC. Is that what's in our bikes? Dunno.

I did dig out my physics book from college, blew the dust off and started looking at pressure calculations.

For an ideal gas (P1*V1)/T1= (P2*V2)/T2. P= pressure in atmospheres, V=volume in liters and T=temperature in kelvin. 1 is the BDC and 2 is TDC. I assumed T stayed the same. I know: false assumption, but it makes calculations easier.

I went with the definition of compression ratio of BDC:TDC. I also assumed the volume could be anything as long as it stayed in same ratio as the compression. In my CR250 it is 8.7:1. For the original example it will be 7.1:1

So the formula for mine is (1atm)(8.7L)=P2*1L. 14.696PSI=1 atmosphere so I get 127.8 psi for mine.

For vallely, I get 104.3 psi.

I know it's not exact, but for all the engines I've checked, it's within 5-10%. I apologize for the  :blah: , but I thought this might shed some light on it.
[/QUOTE]

Verification

Which ocean is California closest to?