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> How do you calculate the cubic inches of an engine? Displacement - the total volume of air and fuel that an engine is theoretically capable of drawing into all its cylinders in one cycle. It's calculated as the volume of a cylinder multiplied by the number of cylinders. The confusing part is calculating the volume uses the area of a circle which requires the radius not the bore (bore = 2 * radius). That is to say: pi-r-squared (calculate the area of a circle where bore/2 is r) x stroke (just like calculating the volume of a cylinder where the stroke is the height) x the number of cylinders. So it's the (bore/2)^2 * stroke * pi * #cylinders. Of course Herb and Dale are correct that it can be simplified to bore * bore * pi/4 * stroke * #cylinders :) I have a calculation page at http://www.ucalgary.ca/~csimpson/Tech/Calculations.html that does this for you. <- shameless plug > For example, if I wanted to bore my 396 a total of .060 over, what > would the cubic inches be? (4.096/2) * (4.096/2) * 3.1415926535 * 3.76 * 8 = 396 ci (4.156/2) * (4.156/2) * 3.1415926535 * 3.76 * 8 = 408 ci Now for the unasked questions. Note: a cycle is 2 revolutions of the crankshaft of a four stroke engine. Right? One revolution is intake and compression while the second is power and exhaust. So you should be sucking in about displacement / 2 * rpms per minute. A 396 cubic inch engine running at 6,000 rpm should require 396 * 6,000 / 2 or 1,188,000 cubic inches of air per minute. Where a cubic foot is 12 * 12 * 12 or 1,728 cubic inches 1,188,000 ci/m would be 687 cubic feet per minute. Compare that to your carburetor size. Note that this does not factor in the efficiency of the motor or the definition of carburetor cubic feet per minute. -- Cliff "Always more than you wanted to know." Simpson http://www.acs.ucalgary.ca/~csimpson/ ----------------------------------------------------- To Unsubscribe please visit www.chevelles.net/list.html To start a new topic, send mail to: [EMAIL PROTECTED]
