Figure It Out!

Print this sheet, play with the math, and place it in your portfolio or folder.

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Well now, you have your dream car body, parts costs, and online research complete.  You will want to re-bore the cylinders of the engine.  Let’s figure the new cubic inch capacity of your engine .


Formula for Cubic Inch Engine Capacity

Bore X Bore X Stroke X 3.1416 ÷ 4 X number of cylinders


The “bore” is how wide your cylinder is.  The “stroke” is the length of the cylinder, or the distance the piston will travel up and down. 



Let’s use a common engine size as an example: a 1979 V8-350 Chevy engine with 160 horsepower.  The bore is 4.0 inches and the stroke is 3.48.  Using these numbers, we get:


4.0 x 4.0 = 16 x 3.48 = 55.68 x 3.1416 =174.924 ÷ 4 = 43.731 x 8 = 349.8 (rounded up to 350) cubic inches


Ok…if your new cylinder is…… what is your new cubic inch engine capacity?


If the bore is now:  and the stroke is: The new engine capacity is:
3.875  3.53  

Change the figures in different columns and work out the results.