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Old 03-08-2009, 05:34 PM
nhdoc nhdoc is offline
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Location: Nashua, NH
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Quote:
Originally Posted by leathermang View Post
...and rounding off sizes to make the math easier....
a four inch piston has a surface area of 4 times 3. 14 for a total of 12.5 square inches. With 100 PSI applied that is 1250 lbs of force. If your crank has a 6 inch throw then you have 7500 lbs of force trying to turn the crank.
Almost...that would actually be you have 7500 in-lbs of torque not force. In fact the offset of the crank is not 6" but shorter than that...so it would probably be closer to about 5000 in-lbs or 400 ft-lbs. Not insignificant but as static force you could counter it by putting the car in gear and setting the parking brake if it is a manual tranny or by devising a clever way to hold the nut on the end of the crank.
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