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# What does RPM actually meanmechanical revolution is measured in "RPM"?

Of course I do realize that it stands for revolutions per minute, but revolutions of what are the revolving pieces that are measured? I assume Assuming it is the crank shaftcrankshaft, how is itRPM calculated, is it by the crank shaft sensor, or by some other means? Why do some old, carbureted cars that runs with a carburetor don'tnot have the RPM meter isa tachometer--is it for the lack of the ECU and the sensor?

Also assuming a 1000 cc bigHere's a scenario:
A 1,000cc 4 stroke-stroke engine with 4 cylinders is running at 1k RPM how. How many times aredoes each cylinder firingfire per second or how? How can thatthis be calculated?

Also, also does the piston "revolve"provide force to the crank shaft with each stroke, even atduring the exhaust stroke with? Does the sameengine create equal torque or is it different at the firingwith each stroke of the piston, ifor do each of the four strokes apply different amounts of power? If so how is, why don't the RPM not constantly going up and downRPMs fluctuate with each different stroke of a cylinder?

# What does RPM actually mean?

Of course I do realize it stands for revolutions per minute, but revolutions of what? I assume the crank shaft, how is it calculated, is it by the crank shaft sensor? Why do some old cars that runs with a carburetor don't have the RPM meter is it for the lack of the ECU and the sensor?

Also assuming a 1000 cc big 4 stroke engine with 4 cylinders running at 1k RPM how many times are each cylinder firing per second or how can that be calculated, also does the piston "revolve" the crank shaft with each stroke even at the exhaust stroke with the same torque or is it different at the firing stroke, if so how is the RPM not constantly going up and down with each different stroke

# What mechanical revolution is measured in "RPM"?

I do realize that it stands for revolutions per minute, but what are the revolving pieces that are measured? Assuming it is the crankshaft, is RPM calculated by the crank shaft sensor, or by some other means? Why do some old, carbureted cars not have a tachometer--is it for the lack of the ECU and the sensor?

Here's a scenario:
A 1,000cc 4-stroke engine with 4 cylinders is running at 1k RPM. How many times does each cylinder fire per second? How can this be calculated?

Also, does the piston provide force to the crank shaft with each stroke, even during the exhaust stroke? Does the engine create equal torque with each stroke of the piston, or do each of the four strokes apply different amounts of power? If so, why don't the RPMs fluctuate with each different stroke of a cylinder?

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# What does RPM actually mean?

Of course I do realize it stands for revolutions per minute, but revolutions of what? I assume the crank shaft, how is it calculated, is it by the crank shaft sensor? Why do some old cars that runs with a carburetor don't have the RPM meter is it for the lack of the ECU and the sensor?

Also assuming a 1000 cc big 4 stroke engine with 4 cylinders running at 1k RPM how many times are each cylinder firing per second or how can that be calculated, also does the piston "revolve" the crank shaft with each stroke even at the exhaust stroke with the same torque or is it different at the firing stroke, if so how is the RPM not constantly going up and down with each different stroke