What's the difference between a three-cylinder and a four-cylinder engine?
3 Answers
The difference between a three-cylinder and a four-cylinder engine lies in their structure: a three-cylinder engine has a simpler structure, is more compact, lighter in weight, and easier to arrange; while a four-cylinder engine is relatively more complex in structure, with an additional cylinder, heavier in weight, and more complicated to arrange. Three-cylinder engines deliver higher torque output at low speeds, but their torque is relatively lower at high speeds, and the power decline is more pronounced. Engines use dynamic balancing technology to reduce vibrations. Due to inherent design, engines with four or more cylinders can balance vibrations among themselves, whereas three-cylinder engines have a larger ignition phase angle compared to four-cylinder engines. Three-cylinder engines are equipped with various vibration damping devices, such as pendulum-type dual-mass flywheels and crankshaft rubber damping technology.
As an old-school car enthusiast who loves studying automotive mechanics, the number of cylinders directly affects an engine's rhythmic character. A three-cylinder engine is inherently unbalanced - pistons always exert force on one side, like a three-legged stool wobbling unsteadily, requiring counter-rotating balance shafts to stabilize it, though the steering wheel still tingles slightly at idle. Four-cylinder engines have pistons moving symmetrically in pairs, pushing and pulling to naturally cancel out vibrations, running as smoothly as a well-balanced sedan chair. Structurally, having one less cylinder means fewer parts - three-cylinder engines are indeed lighter and more fuel-efficient, but at high RPMs they scream like a cracked gong with choppy power delivery. Four-cylinders, however, perform like a symphony orchestra, delivering seamless progressive acceleration and confident highway passing power.
I drove a three-cylinder small-displacement car for three years, and the most noticeable thing was the shaking during traffic light starts. Placing a water bottle on the dashboard at a red light, the ripples on the water surface were much more pronounced than in a four-cylinder car. However, it was more fuel-efficient on the highway, thanks to the reduced friction from one less cylinder. The most frustrating part was the frequent start-stop in traffic—each ignition of the three-cylinder engine felt like a push, while a four-cylinder car was as steady as rolling over and continuing to sleep. But now, new models with hybrid electric motors have quietly smoothed out that initial shake during start-stop. When choosing a car, I recommend testing with a coin on the engine cover—only consider those that can keep it standing upright.
