# Does the flywheel really complete 33 revolutions per second when the engine is set to 2,000 RPM?

My car's RPM meter says x1,000 for each notch, therefore when set to 2 this implies 2,000 RPM. I can't visualise an engine's flywheel turning 33 times per second when the car is set to 2,000 RPM - it seems excessive. Have I misunderstood RPM or is that actually how fast the heavy flywheel turns and the pistons rotate the camshaft?

• divide RPM by 60 and that is the RPS, math does not lie. Pistons rotate the crankshaft, Crankshaft rotates the camshaft.
– Moab
Feb 24, 2020 at 23:54
• Actually, 33 1/3 rps, but yah, this is what it is. Feb 25, 2020 at 2:06
• if your flyweel have an imbalance the shaking will be 33,3 HZ at 2000 rpm you will feel it but not hear it but if you double the rpm you will hear it,but please be nice and do not try this at home or anywhere. Feb 25, 2020 at 7:40
• @Pᴀᴜʟsᴛᴇʀ2 so that's how they arrived at the 331/3 rpm record player...........
– Moab
Feb 25, 2020 at 13:49

yes, that's correct. Now, rotating a flywheel at 2000 rpm is not a big deal: it's well within the capabilities of the material, as long as the flywheel is well-balanced. Other elements in the engine undergo much higher loads.

The pistons, for instance, also go through a full stroke (up+down) 33 times per second at that engine speed, going from 0 to 100 km/h on each stroke. Pistons experience G-forces in the region of 1000 G. Valves undergo similar forces.

These forces are one of the limiting factors in engine speed: these accelerations are so high, you come up against the tensile strength limits of the materials used. High-performance engines require special materials and construction techniques for the pistons, conrods, crankshaft and other reciprocating items.

RPM stands for ROTATIONS PER MINUTE. Converting to RPS (rotations per second) means you divide RPM by 60 (because there are 60 seconds in a minute) and you get RPS.

So your question on 2000 RPM gives us: 2000/60 = 33.33333... rotations/second.

Many modern engines go run much faster than 2000 RPM. Formula 1 engines run in excess of 20,000 RPM which is 333.33333... rotations/second.

You have, however, understood this correctly. While this may seem fast, some devices turn much faster. If you have a turbocharger on your engine, that may turn at speeds of 100,000 RPM or more.

• Is rotations a UK or European vernacular? I've always used revolutions and even inferred that rev-ving a motor was increasing the revolutions per minute.
– user16128
Feb 25, 2020 at 3:14
• @Jeeped they are interchangable but revolutions per minute has its origin in france so it is not even an american word even if it is commonly used there in everything from REVolvers to planes. Feb 25, 2020 at 7:23
• Turbos can go to 180,000 rpm... and they measure the speed with a magnetised nut and a hall effect sensor... Feb 25, 2020 at 9:06
• @SolarMike - Which is why you have to slap an apprentice upside the head the first time they figure out they can shoot compressed air at a clean (sans grease) wheel bearing to spin it up to a high angular velocity without lubrication.
– user16128
Feb 26, 2020 at 12:50