What is the normal cylinder pressure for an engine?

[StPaislee]

For gasoline engines, the cylinder pressure is generally between 8-11 bar, while for diesel engines, it is typically between 12-16 bar. Introduction to cylinder pressure in gasoline engines: For a four-cylinder engine, a pressure of no less than 7 bar is considered normal. Cylinder pressure varies by vehicle model. Generally, large vehicles (such as Dongfeng 140 and Jiefang 141) have a normal range of 6-8 kg, while small cars should have a pressure above 8 kg. If the pressure is below the normal range, it can be determined that the engine has a fault. Precautions for cylinder pressure in gasoline engines: Carefully remove all spark plugs, as inspecting them can reveal many issues. Oily spark plugs indicate wear between the piston rings and cylinder walls or worn valve guides. Burnt spark plugs suggest vacuum leakage. Using a starter to rotate the engine too slowly can lead to inaccurate results.

[LeSadie]

I've handled countless engine repairs, and cylinder compression normal values are the foundation of engine health. For gasoline engines, it generally ranges between 120 to 180 pounds per square inch (PSI), which is approximately 8 to 12 atmospheres. If it falls below this range, say below 100 PSI, it's highly likely due to worn piston rings or valve leakage, leading to hard starting, reduced power, and increased fuel consumption. Use a professional compression tester inserted into the spark plug hole for measurement. The pressure difference between cylinders should be less than 15%, otherwise it may cause backfiring or instability. It's crucial not to ignore wear signals—once significant pressure differences are detected, inspect valve seals or ring conditions to avoid escalating into major issues. Routine maintenance suggests testing every two years or after 20,000 kilometers, especially for older models which require more frequent checks.

[MackenzieLee]

After driving for so many years, engine cylinder pressure is a topic I often talk about. Normal gasoline engines should be around 120 to 180 psi, while diesel engines are higher, approximately 300 to 500. Why is it important? If the value is too low, the car shakes like a sieve at idle; if it's too high, the engine may overheat or even suffer a blowout. From my actual driving experience, a well-maintained car maintains a stable pressure around 150, which slowly decreases over time, especially with frequent stop-and-go traffic in cities accelerating wear. I recommend checking the high-pressure condition every time you change the oil—don’t wait until the warning light comes on to panic. Simply put, normal pressure means smooth driving; if it drops below 110, it’s time to be alert and get it checked.

[Ariel]

As a tuning enthusiast, cylinder pressure is the performance core. Normal gasoline engines are around 120-180 psi, but with a turbocharger, it can surge above 200. The key is to maintain balance with minimal variation between cylinders. Improper modifications can easily exceed limits, leading to piston cracks or cylinder wall scratches. I've seen a friend's car tragically fail due to excessive pressure. Different models have different baselines - Japanese cars often approach the upper limit, while American cars tend to be mid-range. Regular self-checks with a portable cylinder pressure gauge are safe and cost-effective.