What is the normal range for car cylinder pressure?
2 Answers
For a four-cylinder engine, the cylinder pressure should not be lower than seven atmospheres to be considered normal. Not every engine has the same cylinder pressure. Japanese cars typically have around 1100 KPa, while European and American cars range between 1200-1300 KPa. Modern direct injection engines tend to have even higher pressures. More information about car cylinder pressure is as follows: 1. Cylinder pressure data varies by vehicle model. Generally, large vehicles (such as Dongfeng 140 and Jiefang 141) have pressures between 6-8 kg, while small cars should have pressures above 8 kg to be considered normal. If the pressure is below normal, it indicates an engine fault. 2. Since different cars and models have varying cylinder diameters and strokes, this data also differs. The simplest way to check cylinder pressure is to ensure all four cylinders have the same pressure. If one cylinder's pressure differs from the others, it indicates that cylinder is not functioning properly.
Having driven for over a decade, I've encountered all sorts of cylinder pressure issues. The normal cylinder pressure for gasoline engines typically ranges from 8 to 12 bar. If it drops below 7 bar, immediate action is required. Diesel engines usually have higher pressure, around 25 bar. Last time my car had weak acceleration, the repair shop found the third cylinder's pressure was only 6 bar—turned out the valve seals were failing. The pressure difference between cylinders shouldn't be too large, generally not exceeding 1 bar, otherwise the engine will shake. Insufficient cylinder pressure makes the car hard to start, weak on hills, and fuel consumption skyrockets. Regularly checking cylinder pressure during maintenance is crucial—don't wait until a major overhaul to regret it.
