Question 1

What is the difference between HP and PS?

Accepted Answer

HP (mechanical horsepower) is defined as 550 ft·lbf/s = 745.7 W. PS (Pferdestärke, metric horsepower) is defined as 75 kgf·m/s = 735.5 W. PS is about 1.4% less than HP. Japanese and German specifications traditionally use PS, while US/UK use HP.

Question 2

Why do electric motors have higher torque than combustion engines?

Accepted Answer

Electric motors produce maximum torque at 0 RPM because the electromagnetic force is strongest when the rotor is stationary. Combustion engines need to reach a specific RPM range for optimal air-fuel mixing and combustion timing to produce peak torque.