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The horsepower (HP) equation relates torque and rotational speed (RPM) to calculate the power output of an engine. The formula HP = (T × RPM) / 5252 is a fundamental equation in mechanical engineering that demonstrates the relationship between torque, rotational speed, and power.
The calculator uses the HP equation:
Where:
Explanation: This equation shows that horsepower is directly proportional to both torque and rotational speed. The constant 5252 comes from the conversion between different units of measurement.
Details: Accurate horsepower calculation is crucial for engine performance evaluation, vehicle design, mechanical system analysis, and comparing the power output of different engines and motors.
Tips: Enter torque in pound-feet (lb-ft) and RPM values. Both values must be positive numbers greater than zero for accurate calculation.
Q1: Why is the constant 5252 used in the formula?
A: The constant 5252 comes from the conversion between different units of measurement (1 horsepower = 550 foot-pounds per second, and there are 60 seconds in a minute, and 2π radians in a revolution).
Q2: What is the relationship between HP and torque at 5252 RPM?
A: At 5252 RPM, horsepower and torque values are numerically equal. This is why dyno charts always cross at 5252 RPM when both curves are plotted on the same scale.
Q3: Can this formula be used for electric motors?
A: Yes, the formula applies to any rotating machinery including electric motors, internal combustion engines, and turbines.
Q4: What are typical torque values for different engines?
A: Torque values vary widely - small car engines might produce 100-200 lb-ft, while large diesel engines can produce over 1000 lb-ft of torque.
Q5: How does RPM affect horsepower?
A: Horsepower increases with RPM until other factors like breathing efficiency, friction, and mechanical limitations become dominant, causing the power curve to eventually drop off.