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Mean Piston Speed from Stroke & Engine Rate

Calculate mean piston travel speed from stroke and crankshaft rotation rate, or solve either input.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

An 80 mm stroke at 3,000 revolutions per minute gives mean piston speed of 8 m/s. The piston travels twice its stroke in each crankshaft revolution.

Mean piston speed = 2 × stroke × revolutions per second

Worked example

Enter these known values and leave the other values blank.

Full piston stroke
80 mm
Crankshaft rotation rate
3000 / min
Mean piston travel speed
8 m/s

Assumptions and limitations

  • Stroke, rotation rate and mean speed are positive. The rate selector supports revolutions per minute or per second.
  • Mean speed is total piston travel per time. It is not mean signed velocity, which is zero over a full cycle, and it is not the peak instantaneous speed.
  • The formula applies to ordinary crank-driven reciprocation. Connecting-rod geometry affects instantaneous speed but not the two-strokes-per-revolution travel distance. It does not establish a safe engine-speed limit.

Common questions

Is an RPM value used directly as revolutions per second?

No. Divide RPM by 60 when using stroke in meters and speed in meters per second. The unit selector handles this conversion.

Does a four-stroke engine change the factor of two?

No. Each crankshaft revolution still contains one outward and one return piston stroke.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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