What are the differences between three-cylinder and four-cylinder diesel engines?
3 Answers
Here are the main differences between three-cylinder and four-cylinder engines: 1. The three-cylinder turbocharged engine has a simpler manufacturing structure, smaller size, and lighter weight compared to the four-cylinder engine. 2. The four-cylinder turbocharged engine performs better in terms of starting, acceleration, and overall stability than the three-cylinder engine. 3. The three-cylinder engine operates in an unbalanced state, making it more prone to vibration compared to the four-cylinder engine. 4. The three-cylinder engine is louder than the four-cylinder engine, and although balance shaft technology is used, the issue still cannot be completely resolved. 5. Four-cylinder engines are typically used in cars with displacements above 1.3L, and due to their larger displacement, they naturally produce more horsepower compared to three-cylinder engines.
I've been driving diesel vehicles for over twenty years and am familiar with both three-cylinder and four-cylinder engines. The three-cylinder diesel engine has one less cylinder, making it lightweight, compact, and space-saving, especially ideal for small trucks. However, the vibration is noticeably strong—you can feel the steering wheel shaking when idling at a red light, and parts wear out faster over time. The four-cylinder engine, with an extra cylinder, offers smoother and more even power strokes, providing a quieter and more stable ride, especially when hauling heavy loads. But it’s bulkier, with higher maintenance and repair costs. For short-distance deliveries, a three-cylinder is fuel-efficient and cost-effective; for long-haul transport, a four-cylinder offers better comfort and durability.
From a design perspective, three-cylinder diesel engines have fewer cylinders, with ignition occurring only once every 240 degrees of crankshaft rotation, resulting in discontinuous power strokes and inherent difficulties in vibration suppression, requiring reinforced damping devices for compensation. In contrast, four-cylinder engines ignite every 180 degrees of crankshaft rotation, delivering smoother and more continuous power output. Three-cylinder engines exhibit lower frictional losses, achieving 5%-10% higher fuel efficiency at low RPMs, but are more prone to knocking under high loads. Four-cylinder engines feature more optimized exhaust backpressure design, reducing turbo lag. For the same displacement, four-cylinder engines typically offer fuller torque curves and approximately 15% stronger hill-climbing capability.
