[AT] Horsepower Question

[charlie hill]

Ben,  the lawn mower engine is rated in gross hp with no drive train load. 
The tractor engine is rated at net hp, either at the wheels or the PTO. 
There may well be some fudging on the lawn mower engine as well.  Also, HP 
is torque in ft/lbs.  times RPM.  You can make hp with high rpms and low 
torque or high torque and low rpm.   Your tractor is high torque and low 
rpm.  that is what allows it to move a load easily.

Charlie

--------------------------------------------------
From: "Ben Wagner" <supera1948 at gmail.com>
Sent: Wednesday, October 06, 2010 9:00 AM
To: "At" <at at lists.antique-tractor.com>
Subject: [AT] Horsepower Question

>  Here is a puzzler that maybe someone with a better knowledge of
> engines can answer.   I was asked this question, and had to announce
> that I needed to look it up.  What better place than the AT Mailing?
>
> I have a Super A with four cylinders, producing c. 20 HP.
>
> I have a lawnmower, with an engine that says it is also 20 HP, with only
> two cylinders.
>
> What is going on?  Is this two different measures of HP?  Or has
> technology improved that much?   What makes a little two cylinder "small
> engine" have the same HP as four cylinder "tractor" engine.
>
> Thanks,
> Ben Wagner
>
>
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