What is the standard value of engine cylinder pressure?
2 Answers
Gasoline engines have a standard cylinder pressure value of 8-11 bar, while diesel engines have a standard cylinder pressure value of 12-16 bar. A cylinder refers to the combustion chamber in a car where there is a piston driven by the pressure or expansion force of the working fluid. The classification of cylinders is as follows: 1. Single-acting cylinder: Only one end has a piston rod, with gas supplied from one side of the piston to generate pressure, which pushes the piston to extend. It returns via spring or self-weight. 2. Double-acting cylinder: Gas is alternately supplied from both sides of the piston, producing force in one or two directions. 3. Diaphragm cylinder: Uses a diaphragm instead of a piston, producing force in only one direction and resetting via spring. It has good sealing performance but a short stroke.
I usually pay attention to car maintenance. The standard cylinder pressure value generally ranges between 120 to 180 psi (pounds per square inch), depending on the engine type. For gasoline engines, newer ones tend to be closer to the upper limit, while older vehicles may drop to around 100 psi. Diesel engines have higher pressures, sometimes exceeding 200 psi. The compression ratio is a key factor—higher compression ratios require greater pressure; otherwise, combustion efficiency will suffer. When measuring, use a cylinder pressure tester by inserting it into the spark plug hole and starting the engine to get a reading. Remember to warm up the engine to normal operating temperature first for accurate results. If you find the pressure is low, it could indicate issues like valve sealing problems or worn piston rings, which should be addressed promptly to avoid power loss. Regular checks can improve fuel economy and extend engine life. I recommend car owners test it every two years or every 20,000 kilometers to prevent minor issues from turning into costly major repairs.
