Torque Calculation

Joined: Mar 12, 2007
Points: 452

Torque Calculation
Original Message Jan 3, 2009 12:31 am

I’m trying to calculate the Torque my Ariens Snow Thrower produces but I spent too much time in math class daydreaming about a girl (her name was Stephanie). So anyway I’m not sure if I’m calculating this correctly. Feel free to quality check...

I recall that:

Horsepower = (Torque x RPM) / 5252 ... With the torque measured in ft-lbs

So then: Torque = (HP x 5252) / RPM

If that’s the case them my Ariens 11528 produces:

Torque = (11.5HP x 5252) / 3600RPM

Torque = 60398 / 3600

Torque = 16.7 ft-lbs

Does that seem right?

This message was modified Jan 3, 2009 by Paul7

MacLorry27

Joined: Dec 23, 2008
Points: 54

Re: Torque Calculation
Reply #1 Jan 3, 2009 8:20 am

Paul,

Your formula is correct. The only thing I would add is that max torque and max horsepower almost always occur at different RPMs, with max torque never being at a higher RPM than max HP (because It's a mathematical impossibility).

Major small engine manufacturers measure torque and HP in accordions with SAE J1940. According to this code torque is measured at 3060 RPM and horsepower at 3600 RPM. However, an engine’s true max torque and/or HP could occur at other RPMs. Lacking specific information, commenters on sites such as this assume that rated torque and/or HP occur at 3600 RPM. Otherwise, we wouldn’t have enough information to solve the formula, and what fun would that be?

Mac

Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions