Compression Ratio

If a stock Cleveland with closed heads ('71) had a compression ratio of 10.8 to 1, what would the ratio be if the cylinders were bored to .030?

mike

How's your math skills. http://www.csgnetwork.com/compcalc.html. You'll like this. did it manually once.

How's your math skills. http://www.csgnetwork.com/compcalc.html. You'll like this. did it manually once.

Click to expand...

Have to get my slide rule.

mike

Nah! Just good measurements.

Pulled out what I wrote on a piece of paper when I did it on my 454 .030 over

57.55+.216+.275+.795+5.98 64.18

________________________= _____ = 8.92:1 w/ flat top 2 valve relief

.216+.275+.795+5.98 7.266

So we had to greatly improve on the last rebuild!

DAHH! forgot to give you the formula.

Cylinder volume+clearance volume+piston volume+head gasket volume+chamber volume

________________________________________________________________

Clearance volume+piston volume+head gasket volume+chamber volume

Sorry

Nah! Just good measurements.

Pulled out what I wrote on a pice of paper when I did it on my 454 .030 over

57.55+.216+.275+.795+5.98 64.18

________________________= _____ = 8.92:1 w/ flat top 2 valve relief

.216+.275+.795+5.98 7.266

So we had to greatly improve on the last rebuild!

DAHH! forgot to give you the formula.

Cylinder volume+cleaance volume+piston volume+head gasket volume+chamber volume

________________________________________________________________

Clearance volume+piston volume+head gasket volume+chamber volume

Sorry

Click to expand...

Addition involved also? Have to get my abacus.

Neither slide rule nor abacus use batteries.

mike

It's not that bad. But good to know when:

"We have great plans for the future" during your rebuild!

If a stock Cleveland with closed heads ('71) had a compression ratio of 10.8 to 1, what would the ratio be if the cylinders were bored to .030?

mike

Click to expand...

It should increase about .1 assuming the new piston is exactly the same except for the + .030 diameter. You may want to look into what the original compression was in 71 for M code. It seems I remember reading something about stated and actual CR being different, actual being lower almost a full point. http://www.network54.com/Forum/119419/thread/1316459553/Ford+Camshaft+Data

This link for general calculations, others slightly more accurate but require data you may not have. .http://www.wallaceracing.com/cr_test2.php

Chuck

Possibly you can find something here that may be easier.

http://www.wallaceracing.com/Calculators.htm