Originally Posted by fc735
compression gauge readings are not "exact" you can test it tomorrow under different conditions and it will be different.
there is no way to compare the pressure reading to a compression ratio, CR is not definitive to PSI.
15psi difference is common. general rule of thumb is anything more then a 10% variance from highest to lowest is an indication of trouble, and a leakdown test should be performed to determine the cause.
and Snap-On diag equip=teh overprice. i got my Mac kit with diesel gauge and adaptors for what Strap On wanted for just the gauge and auto hoses.
dont even get me started on the Modis.....
snap on is hella overpriced for diagnostics...but when it comes to hand tools and what not you cant fuck w/ 'em. mac shit breaks so easy it's unbelievable. but yeah you said it how i wanted to say it but didnt know how to word it. just because a motor may put down 220 across the board doesnt mean it's stronger than a motor that puts down 180psi across the board. there are too many variables like cams and timing and what not.