For years all anyone cared about at the traffic light start line was how much horse power your car had but with the rise of powerful diesel engines Torque has become a talking point. So what is the difference between BHP (Brake Horse Power) and Torque writes Suzanne Keane
Brake Horse Power has been around since engines were first invented. It was a measure that compared the power of a horse – a James Watt experiment in the early 1700s calculated that a horse could raise 330lbs by 100 ft in one minute – to an engine. This method of measuring horse power was used in the UK and USA. The Germans invented their own standard which was referred to as PS DIN. In Ireland we use a combination of kW, BHP and PS DIN but they basically all mean the same thing – the measure of power an engine produces.
Torque, on the other hand, is a twisting force and can only be applied if there is resistance and is measured in Newton metres – turning force generated at the crankshaft. The more torque an engine can produce and the faster it can do it decides how much power it produces. Diesel engines, in general, produce more torque mainly due to the high compression ratios and the fact that they have a smaller bore and a longer stroke.
BHP may help out with top speed but Torque is what will get you there. The more torque your car has the more power it will give you at a lower rpm – however, on a long straight drag race the car with higher bhp will win in the end!
In summary, Torque produces the power and BHP measures how much! They can’t exist without each other but what you need the engine to do will decide which you prioritise! If, for example, you want to move heavy loads (tractor, towing a caravan) torque should be your priority but if you were building a race car you’d be looking at BHP first.
30th September, 2015