Well, measurements from a compression test can't really be converted into a compression ratio. even tho the measurements from a compression test are in lbs/sqin (psi) it has nothing to do with the compression ratio. A compresion test simply test the static pressure that can be sustained in the cylinder. Tells you if your rings are shot or if there is the valves aren't seating correctly.
An engine with a CR of 11:1 might have a Compression Test Results of 160 psi per cylinder.
An engine with a CR of 8.5:1 could have results of 170 psi per cylinder.
The only way to measure compression is to measure the cylinder chamber
volume when the engine is at TDC (Top Dead Center), and measure the volume of the cylinder when the engine is at BDC (Bottom Dead Center)
CR = (volume of cylinder at BDC volume of combustion chamber at TDC) divided by (volume of combustion chamber at TDC).
There are a few methods to do this, using wax, oil,water or alcohol
I preffer the alcohol method because it's easiest to clean and will evaporate quickly when your done. water could be a poor choice because it is incompressable and can cause some damage if water is left in the cylinder.
That's basically the idea of measureing CR tho there are more exact ways.
calvin@Oct 8 2002, 10:08 AM I want to know how much boost a mini me setup can take, if tune correctly.
Well you can't simply ask how much boost can I run. you need to be clear on your desired application, is it for autoX, Drag Racing, Just for some more poer on your daily driver. Along with a proper choice in which turbo to use, you'll need to do some engine build-up. some forged pistons like JE, Stronger Rods, Re-Sleeve the cylinders, an ignition system, and other things which will make the set-up less prone to failure.
To make it simple you can't just slap a turbo on a car and say I wanna out this much boost into it.