Formula for corrected torque

[jmeehan]

I received an e-mail from Blane at Browns Valley RV. Several of us that attended his dyno day's wanted to correct our rear wheel torque.



Here's the formula: Torque=HPx5252/RPM.



If you have the torque and want to find the HP it's: HP=torquexRPM/5252.



I'm kind of curious what the 5252 represents. Blane got the formula from his dyno and software builder, so maybe it represents something that is particuler to his dyno?

 

[nickleinonen]

the 5252 is a constent value. that formula has been around for a long and is the standard formula for converting HP to torque. it's not unique to that dyno

 

[Rman]

5252 is a mathematical constant... kind of like pi, it's just there. Where's Hohn at, he REALLY digs this formula... i'd be willing to bet he has a mural on his wall of it

 

[RustyJC]

1 BHP = 33,000 ft-lb of work per minute



Divide 33,000 by 2 x pi to convert linear work to rotational work since 2 x pi radians = 1 revolution (360 degrees).



33,000 / (2 x pi) = 5252



BHP = (Torque x RPM) / 5252 is derived from the following formula:



BHP = (P x L x A x N) / 33,000



Where:



P = Brake mean effective pressure (the average pressure applied to the top of the piston during the power stroke), measured in PSI



L = Length of stroke, measured in feet



A = Area of one cylinder, measured in square inches



N = Number of power strokes per minute. For a 2-cycle engine, this is equal to RPM times the number of cylinders. For a 4-cycle engine, this is equal to RPM times the number of cylinders divided by 2.



33,000 = 550 ft-lbs of work per second (1 BHP) x 60 seconds per minute



Rusty

 

[Rman]

dang it rusty! I was looking up the numbers in my book and you beat me too it! oh well, all for not.