Compression calculator
by Paul Willis (

With this calculator, you can estimate compression based upon values of key components.

Select the Bore Size Select Piston Clearence
Select the Stroke Select Cylinder Head Chamber Volume
Select the Deck Height * Select Piston Dome/Dish Volume **
Select Head Gasket Bore Size Select Head Gasket Thickness

* Deck Height values that are negitive (eg. -0.010") means that the piston is below the deck surface. Postive values (eg. 0.006") means that the piston is above the deck surface.

** Piston Dome/Dish Volume includes the valve reliefs. For example the stock 5.0 flat top pistons have a volume of 4.6 cc because of the four valve reliefs. This excludes 1986 5.0's which had no valve reliefs.