Enter the number of cylinders,
the bore, and the stroke of the engine. This information will be used
to calculate the displacement. The bore is also necessary for the calculation
of the compression ratio.
Enter the volume of the pistons and combustion chambers
(in the heads). The head chamber volume is always positive. The piston
volume is positive if it is dished, zero if it is flat, and negative if
it is a dome piston. This data is used to calculate the compression ratio.
Enter the Piston Deck Height
and the Compressed Head Gasket Thickness. The Piston Deck Height (also
known as the "Installed Height") is the distance that the
piston protrudes above the top of the block. It is negative if the piston
top is below the top of the block. The total piston to head clearance
is the Compressed Head Gasket Thickness - the Piston Deck Height. This
data is used to calculate the compression ratio.
This section contains the results
of the calculations. The displacement can be entered if you want it
translated to other units, or if you want to calculate the Maximum Air
Enter the Volumetric Efficiency
and Maximum speed. The displacement can be entered above, or calculated.
While you won't see the volumetric efficiency of an engine stated very
often, a good guess will get you close enough to choose the correct
carburetor or throttle body. Most stock engines have a volumetric efficiency
of 75-80%. Modifications (intake manifold, cam, exhaust, porting &
polishing, etc.) can bring this up to 80-85%. Really highly tuned engines
can actually go above 100%, but this occurs over a very small speed
range. Forced induction engines (turbocharger, blower, etc.) can go
well above 100%. From this data, the Maximum Air Intake Requirements