The compression ratio of an engine will determine its performance. Generally, if the volume of the cylinder when the piston is down is greater than the volume of the combustion chamber when the piston is up, the space is calculated as the ratio of the volume. When the intake and exhaust valves are closed, the air does not come out, the piston increases, and the air-fuel mixture is compressed. Compression ratio refers to how the cylinder gap changes from when the piston is down to when the piston is up. Five factors define this equation: cylinder displacement volume, compression volume, piston dome, head gasket volume, and chamber volume. To calculate the ratio for your vehicle, you must use the formula, compression ratio = volume at bottom dead center divided by top dead center. It's not as simple as it sounds, but if you know a few key measurements, you can calculate the compression ratio.
Step 1. Locate your user manual; It will be necessary to measure some parts of your engine
Step 2. Clean your engine as much as possible with an engine degreaser before starting your job
Step 3. Measure the cylinder bore with a caliper
Step 4. Measure the cylinder distance from the bottom piston to the top to find the cylinder threshold
Step 5. Find the volume of the combustion chamber (from manufacturer or manual)
Step 6. Find the compression measure of the piston (from the manufacturer)
Step 7. Find the volume of the piston dome (from the manufacturer)
Step 8. Calculate the compression from the piston to the cover (gauge x caliper x distance between piston and cover at top dead center)
Step 9. Measure the gauge and thickness of the cylinder head gasket
Step 10. Use the following formula to calculate the compression ratio when you have all the above measurements:
cylinder volume + compression volume + piston volume + gasket volume chamber volume.
Step 11. Convert cubic centimeter measurements, if necessary, from inches by multiplying inches by 16,387
You can also put your measurements into a compression ratio calculator that you can find on any web page instead of doing the calculations yourself
- Make sure you use the proper tools when working on your car's engine. An inappropriate tool can separate or break and cause a serious injury to you or someone nearby.
- Take proper precautions when working on your car's engine. Make sure the engine parts are cool before starting and wear protective gear like safety glasses, closed shoes, and gloves.