Car Power Defined

What's The Difference Between BHP, HP, kW and PS?

Manufacturers can often pick and choose between power units, so here's a
low-down of what they all equate to

Kilowatts

1kW = 1.341hp

Technically, this form of measurement is the most uniform method of measuring power and is used by every engineer worldwide. Watts are an SI unit (International System) which means they are based around the metre, kilogram, joule and second that make up the metric system. It is a measurement of energy transfer over time, which is the exact job that an internal combustion engine undertakes.

Horsepower

Created by the master of the steam engine – Mr James Watt – this unit of power has somehow still survived to this day as the staple unit of power measurement of new cars where I’m from. Horsepower was deemed equivalent to a horse moving 33,000 pounds of mass one foot in one minute. Now no one knows how big this horse was or whether it was a particularly healthy horse or not…but let’s just go with it. This new-found unit allowed Watt to show direct comparisons between his steam locomotives and the common horse that dominated the haulage business up until the invention of the steam engine.

PS

1PS = 0.986hp

PS stands for pferdestärke which translates simply as horsepower, but it has had some metric tweaking to try and bring good old HP forward into the 21st Century. This metric horsepower has been adopted throughout Europe as the new standard for power measurement and will probably make its way fully into the UK psyche in the not too distant future.

The official engineering standard for metric horsepower is the amount of power needed to lift a 75kg of mass one metre vertically in one second, which – once the conversions from imperial to metric are applied – equates to a 1.4 per cent higher figure than the old imperial units. Manufacturers will often pick and choose between PS and HP depending on whatever figure seems more rounded and presentable. Although I’ve always just seen PS as ‘horsepower plus a few’.

(CarThrottle.com)