What is the normal cylinder pressure for a car?

[StKennedy]

Car cylinder pressure is normal between 1100 and 1300 kPa. The reasons for insufficient engine cylinder pressure are: 1. Insufficient cylinder lubrication causing cylinder scoring, leading to excessive wear on the cylinder walls; 2. Poor or damaged cylinder gasket sealing, resulting in insufficient airtightness between the cylinder block and cylinder head; 3. Excessive flatness of the two contact surfaces between the cylinder head and cylinder block, causing poor cylinder sealing; 4. Intake and exhaust valves not closing tightly; 5. Car cooling system failure leading to insufficient engine cooling. The solutions for insufficient engine cylinder pressure are: 1. Replace piston rings or cylinder liners; 2. Replace the cylinder gasket and tighten the screws to the specified torque; 3. Check if the water passages are clear, pay attention to adding coolant, and promptly replace and eliminate any leaking areas.

[MacChristian]

Last time I tested my old Japanese car, the mechanic said the normal cylinder pressure for regular family cars is generally safest between 8 to 14 bar. For example, my 1.6L naturally aspirated engine just measured 11 bar, and the mechanic said it was in good condition. However, actual values can be affected by oil temperature—it might read 1-2 bar lower when the engine is cold, so it's best to measure when the engine is warm for accuracy. If cylinder pressure drops below 8 bar, you should be alert—common causes include valve leakage or piston ring wear. Last week, my neighbor's car had to undergo a major engine overhaul because the cylinder pressure was only 6 bar. Turbocharged cars usually have higher cylinder pressure—some German models can reach up to 15 bar—but anything below 10 bar is definitely a problem.

[OwenRose]

Cylinder pressure values can't be generalized. My modified car with 11:1 compression ratio needs to maintain cylinder pressure above 13 bar. For regular commuter cars like the Sylphy or Corolla, the service manual specifies a standard range of 10±1 bar. At the repair shop last time, I saw a case where a car with 150,000 km had cylinder pressures of 7.8/8.2/6.5/7.9 bar across four cylinders - turned out to be stuck piston rings. Important measurement notes: throttle must be fully depressed to keep it wide open, battery charge must be sufficient, and it's best to take three measurements per cylinder and average them. Different brands have different standards - American cars typically run about 1 bar lower than Japanese models.

[Shannon]

Just helped a friend inspect his 100,000-kilometer Fit. The cylinder compression for all four cylinders is between 9.8 and 10.3 bar, which indicates a very healthy condition. When new, the factory cylinder compression is generally between 12-14 bar, and it gradually drops to around 10 bar as mileage increases. If the compression difference between adjacent cylinders exceeds 1 bar, it might indicate a blown head gasket. Diesel engines have higher cylinder compression, typically starting at 18 bar. If you find one cylinder particularly low during measurement, you can pour a bit of oil into the spark plug hole and measure again. If the compression improves, it's likely a piston ring issue; if there's no change, it's probably valve leakage.