Does a Bored Engine Have the Same Power as Before?
2 Answers
Boring the cylinder generally results in a decrease in vehicle power, mainly due to the following reasons: 1. Reduced Air Tightness: The cylinder's air tightness deteriorates. After boring, the inner wall of the cylinder is not as smooth as it was when it left the factory, causing the compressed air-fuel mixture to leak during piston compression, leading to lower cylinder pressure and affecting the vehicle's power. 2. Increased Volume: The combustion chamber volume increases while the fuel injection amount remains unchanged. Boring increases the cylinder diameter and piston size, which enlarges the combustion chamber volume and reduces cylinder pressure. 3. Cost of Boring and Grinding: The repair costs for boring and grinding vary significantly across different vehicle models. Additionally, after boring and grinding, components such as pistons and piston rings must be replaced, as old pistons cannot properly break in with the new cylinder walls. The cost differences for these parts also vary greatly between models, making it difficult to generalize.
A few years ago, I had my car's cylinders rebored for repair. The power felt about the same as before, but it really depends on the specific situation. Back then, the power loss was due to cylinder wear, and after the repair, the engine's performance was restored to factory standards with minimal noticeable difference. If the machining process is precise, it ensures stable sealing and compression ratio, making the car drive as smoothly as a new one. However, if the reboring size is adjusted too much, the increased displacement can boost power, but fuel consumption also goes up—I’ve experienced this myself, and it wasn’t really worth it. For daily driving, it’s best to test the acceleration after the repair, checking for any unusual noises or vibrations. In short, proper cylinder reboring can restore power, but it’s crucial to choose a reliable repair shop to avoid compromising longevity just to save money.
