United Engine & Machine Piston Calculators

To choose the calculator you wish to use, just click on the title. You can scroll down to the bottom of this page to read more about each calculator.

This calculator will give you the proper compression ratio with a know piston head volume. It will also estimate a dynamic effective compression ratio taking into account the cam timing and rod ratio.

This calculator will give you a dynamic compression ratio taking into account cam timing and rod ratio.

This calculator will give you the proper piston head volume with a known compression ratio.

Convert inches to millimeters or millimeters to inches.

Using this calculator, you can obtain the proper ring end gap requirements for KB Pistons using end gap factors from inside the front cover of the KB catalog or on this web site in the tech article titled "Special Clearance Requirements for the KB Piston.

Use this calculator to get the approximate piston compression height.

This calculator will compute the deck clearance for above or below deck applications.

Find the engine displacement based on stroke and cylinder measurements.

• While these calculators will calculate out to six (6) decimal places, they will round to three (3) decimal places when they are displayed, and any figures you enter will also be rounded to three (3) places when the results are displayed.

  
  

• These programs have been designed to be used with Microsoft Internet Explorer 5.5 or above.  While they should function properly with other browsers, you may experience some inconsistencies in the way the data is entered and displayed.

  
  

• Piston Head Volume and Deck Clearance.  Values for Piston Head Volume and Deck Clearance can be entered as both positive or negative values. Negative numbers indicate a reductions in cylinder head volume. Pistons with pop-ups or pistons sticking out above the deck will reduce chamber volume and would usually require a negative number. Pistons with a dish or pistons below deck increase chamber volume and receive a positive value.  Located above each picture in the KB Catalog is the value for the piston head volume shown in positive or negative numbers.

  
  

• Deck Clearance.  Deck clearance should be measured from the top of the block to the flat portion of the piston. Do not measure to the top of the pop-up or the bottom of a dish.  With some pistons this flat area may be very small (example: Chrysler Hemi is only a line at zero deck).

  
  

• Gasket Bore.  If you do not have the exact gasket bore use the cylinder bore in it's place.

  
  

• Piston Head Volume.  On the piston calculator many times you will come up with a piston head volume that approaches zero. When this happens the valve relief's and the pop-up are approximately equal in value.