Concept of horsepower in Automobiles

What is Horse Power?

Horse power by Royal society of Physics is “work done @ 33000 ft lb per minute.
A horse can pull 330 lbs weight over a distance of 100 ft in one minute. This was defined as one horse power

Now power is Work done/Unit Time, also Power= torque x angular momentum. Unit of power is Watt (W).

What is Physical value of Watt ?

1 watt is equal to 1 joule/second, 1 joule is 1 N-m (joule is unit of energy, by thermodynamics 1^st law- work & energy are equal). 

So Watt is 1 joule energy generated in 1 second. In electrical point it is 1 Watt=1V*1A. 

A person having a mass of 100 kilograms who climbs a three-meter-high ladder in five seconds is doing work at a rate of about 600 watts. 

Also 1 Calorie is equal to 4.184 Joule. 

And Work is Force * Distance [Here don’t confuse with torque it is Force * Perpendicular distance].

Engines were invented in early days of industrial revolution. At that time, in order to compare which engine was more powerful, a standard of measurement was required. Mostly, these engines were used to do work which were earlier done by horses, a lot of experiments were conducted to determine the power of a horse.

Name of James Watt is prominent among the scientists involved in these experiments. It was concluded that an horse will pull 330 pound weight over a distance of 100 ft in one minute.

1 Horse Power = 33000 ft-lb per minute or 550 ft-lb per second.

1 Horse Power  = 746 Watt

What is BHP, HP , PC, KW & KWh in power output of engine?

In essence, HP, BHP, PS, CV and kW all refer to the amount of power that an engine produces. Or, in less technical terms, how much ‘work’ it can do. As a rule of thumb, the higher the horsepower, the faster a car can ultimately go.

BHP stands for Brake Hose power, total engine output measured at flywheel.

HP is stands for horse power, which is equal to 746 watt.

PS or Metric Horse Power :- It is 98.6% of BHP, mostly called PS (Pferdestake) used in Germany. So metric horse power will be 736 watt. 

So Kw>HP>PS>BHP

KW stands for Kilo watt, is unit of power. KW is equal to 1000 watt.

KWh stands for kilo watt hour, unit of energy (it mean how much energy that actually used or generated in 1 hour).

Both KW & Kwh explain battery capacity. KWh defines how much energy the battery pack has available to provide to electric motor.

List of Vehicle having maximum power.