[Car Knowledge] What do engine displacement, number of cylinders, horsepower, and torque represent respectively?
1. Engine displacement
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definition :
The total volume of air and fuel mixture that all the cylinders of the engine can accommodate in one operating cycle is usually expressed in "cc" (cubic centimeters) or "L" (liters), for example 1500cc, 2.0L. -
Practical significance :
The larger the exhaust volume, the more mixed gas can theoretically be burned, and the more power can be generated. -
Example :
The displacement of general family cars is usually 1.5L~2.5L, while performance cars or sports cars have 3.0L or even more.
2. Cylinders
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definition :
The number of "pistons" in the engine, commonly 3, 4, 6, 8 cylinders, etc. -
Arrangement :
In-line (I), V-type (V), horizontally opposed (Boxer/H). -
Practical significance :
- More cylinders : smoother operation, greater power output, and deeper sound (such as V6 and V8).
- Small number of cylinders : light, fuel-efficient, and low maintenance cost (such as I3 and I4).
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Example :
Most family cars have 4 cylinders, while luxury or high-performance cars often have 6 or 8 cylinders.
3. Horsepower (HP/Ps)
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definition :
How much "work" (kinetic energy output rate) an engine can do in one second is an important indicator of top speed and acceleration capabilities . - Common units : horsepower (HP, Ps), kilowatt (kW).
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Practical significance :
- High horsepower means that the engine can continuously output strong power at high speed and has stronger acceleration ability.
- Suitable for vehicles that pursue high speed and require high power.
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Example :
Generally, family cars have about 100~200hp, while performance cars have over 300hp.
4. Torque (Nm/kgm)
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definition :
The engine generates "torque" on the drive shaft, which is the rotational force . The unit is Newton meter (Nm) or kilogram meter (kgm). -
Practical significance :
- With large torque, the vehicle starts powerfully and accelerates quickly, and performs better when climbing hills and carrying loads.
- Torque is high at low rpm, which means the car is "powerful as soon as the accelerator is pressed."
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Example :
The torque of a family car is about 150~250Nm, and that of a diesel car or SUV is higher.
Simple metaphor
- Exhaust volume : like the "lung capacity" of a motor - how much air it can absorb and how much fuel it can burn.
- Number of cylinders : It’s like the “number of muscles”—the more cylinders, the smoother the power and the greater the output.
- Horsepower : Like "sprinting ability" - how fast it can run and how fast it can accelerate.
- Torque : It’s like “starting power”—how hard you can pull and how powerful you can start.
Practical car selection advice
- Commuting and urban vehicles : small or medium displacement and smooth torque output are sufficient.
- Long distance, high speed, and performance requirements : choose a car with higher horsepower and torque.
- Cargo, off-road : Torque is more important than horsepower.
Tips :
Modern turbocharging technology can give small-displacement engines high horsepower and high torque, balancing performance and fuel consumption!
