What is RPM?

By David Morley, 23 May 2016 Car Advice

RPM gauge on instrument cluster

Ever wondered what that big gauge next to your speedo really does? It’s called a tachometer, and you probably ignore it, but it monitors your car’s engine speed. This is how it works.

RPM is a term you’ll hear a lot if you hang around with people who love their cars.

It stands for Revolutions Per Minute, which gives you a big clue as to what it’s all about. It’s a measure of how fast a car’s engine is turning at any point in time.

The important, oily bits of an engine spin inside the motor when it’s running. That’s normal, and how the engine converts petrol into the movement that gets you everywhere from work through the week to the Gold Coast for holidays.

When those internal bits and pieces complete one full rotation, that’s one revolution. And if they do it 3000 times a minute, that’s 3000rpm.

Most modern cars idle at between 500 and 1000rpm (at which point those internal bits would still be a blur to the naked eye; 600rpm is still 10 full rotations every second) and most engines will max out rpm-wise at between 6000 and 8000rpm. And the gauge on your dash that displays rpms is a tachometer, or tacho.

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