I was asked what is the difference between BHP and PS which can seem confusing as different manufacturers use different ways to give the power output of their engines. I explained as best I could that they are essentially the same thing but it spurred me on to so a little research.
While ‘horsepower’ refers to an engine’s total output, brake horsepower only looks at the amount of energy left once other parts like the gearbox, alternator and water pump have all been powered. It’s measured at the road wheels, not at the flywheel. PS is the abbreviation for ‘Pferdestärke’ – German for horse-strength.
One PS is about 98.6% of a brake horsepower – the two are virtually interchangeable. PS is sometimes referred to as ‘metric horsepower’.
Some car-makers quote engine power in in kilowatts – especially on the Continent.
Despite kW being the EU’s ‘legal’ engine power measure since 1992, it is used far less than PS or BHP. A kilowatt (kW) of power is about 1.34bhp.