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`RPMs = "ps" / ( s * 2)`

Enter a value for all fields

The **Engine RPMs** calculator computes the revolutions per minute (RPMS) based on the average (mean) speed of the pistons, and the stroke length.*One rev*

**INSTRUCTIONS:** Choose units and enter the following:

- (
**pS**) Mean Piston Speed - (
**s**) Stroke Length

**Engine RPMs:** The calculator returns the engines RPMs.

The equation for the RPMs of an engine is as follows:

`RPMs = (ps)/(s*2)`

The Piston Speed equation calculates the mean velocity of the piston based on the cylinder stroke length and the RPMs. The piston's speed of travel up and down the cylinder is always changing and actually comes to an instantaneous stop at both the upper and lower ends of the stroke at the beginning and end of a single revolution. Therefor we can only calculate the average (mean) velocity based on RPMs. In one minute, the pistons travel two times the stroke length times the number of revolutions (2 * Stroke * Revs). Divide that by one minute and you have the mean piston speed.

Inch Equivalences |
|||

Fraction | Decimal | Mils | |

1/16^{th} |
0.0625 | 62.5 | |

1/32^{th} |
0.03125 | 31.25 | |

1/64^{th} |
0.015625 | 15.625 |

**Cylinder Bore Diameter**based on the engine displacement, number of cylinders and the stroke length.**Bore Stroke Ratio**based on the diameter of the bore and the length of the stroke.**Combustion Ratio**base on the minimum and maximum displacements of the cylinder at the beginning (1-Induction) and compressed (3-Power) portions of the combustion cycle**Displacement Ratio**based on the volumes at the beginning and end of the stroke.**Rod and Stroke Length Ratio**base on the two lengths.**Stroke Length**based on the total engine displacement, number of cylinders and the bore.**Piston Position**based on the crank angle, crank radius, and rod length.**Total Volume (displacement) of a Combustion Engine**based on the bore, stroke and number of cylinders.**Volume (displacement) of a Engine Cylinder**based on the bore and stroke.**Volume (displacement) of an Engine with an Overbore**based on the stroke, bore, overbore and number of cylinders.**Equivalent Volume of a Rotary Engine**based on the swept volume and number of pistons.**Compressed Volume of a Cylinder**when the piston is at the end of the stroke and the chamber is at its smallest (and most compressed) volume, based on the chamber, deck, crevice, chamfer, gasket, valve relief and dome/dish volumes. This is the second volume (V2) in the Compression Ratio**calculation.****Volume of a Gasket**based on the inner and outer diameters and the gasket's thickness.**Volume of a Cylinder Deck**based on the deck height and the bore.**Volume of a Cylinder Crevice**based on the piston diameter, cylinder bore and the crevice height.**Volume of a Cylinder Chamfer**based on the cylinder diameter and the chamfer height and width.**Piston Speed (mean) based on stroke length and RPMs.****Max Piston Speed based on stroke length and RPMs****RPMs based on desired piston speed and stroke length**.

- Camber Angle
- Camber Offset
- Breakover angle - Ground clearance between axles
- Approach angle - Ground clearance in front of or behind vehicle.
**Belt Length****Belt Speed**.**Pulley RPMs****2nd Pulley RPMs****2nd Pulley Diameter****RPM of 4th pulley on three shafts****2nd Gear RPM**