What is Horse Power?
The power, in simple terms, is ‘rate or speed of doing work’. The work is defined as a  ‘force operating thru’ a distance‘. The automotive engines use the term ‘horse power‘ (hp) to measure its power.

1 hp (mechanical) = 33,000 ft·lbf/min = 550 ft·lbf/s

A conventional engine produces its power by burning the fuel. The combustion process releases the heat energy which results in the generation of expanding forces known as power.

The engine’s power is commonly measured in Brake-Horse-Power (bhp

B.H.P = (Torque x RPM) ÷ 5252

Most automotive engines produce power in a wide band of the engine’s speed. Although the power output varies from engines to engines, it is characteristically highest at the top-end of the engine’s rpm range.

The power output of an engine is usually represented in the graph as a curve against the engine rpm band.

The power curve in an engine represents its rate of doing work corresponding to engine’s rpm band. Higher the power an engine can produce means that it can do more work OR give higher performance.

Power is most useful while speeding & overtaking. The vehicle often needs more power when it is climbing a gradient as the engine has to pull the vehicle’s weight against the forces of gravity.

Theoretically, the engine speed range between ‘peak-torque’ rpm and ‘max-horse power’ rpm is known as ‘Power-Band’. It is the range in which the engine is most efficient & gives the best performance.

If you change the gears within the ‘power-band’, you are likely to get the best fuel efficiency from your vehicle. So, read the ‘Engine Specifications’ in the Owner’s Manual to know about the ‘power-band’ of your engine.

the engine horse power can best be used in collaboration with the engine’s torque and thereby changing the gears accordingly.

Every engine reaches its Max. Power value when you rev it to the full throttle before the ECU cuts off its fuel supply. So, manufacturers mention this value in the Owner’s Manual under the ‘engine specifications’. For e.g. ‘Maximum Power: 97 bhp at 5000 rpm’