[AT] Horsepower Question

[John Wilkens]

Somewhat related....I have an interesting old single cylinder Economy 
engine that weighs over 2000 lbs and is rated 9 HP......but at a 
working speed of only 325 RPM.   6" piston and 12" stroke.         John W.



At 07:00 AM 10/06/2010, you wrote:
>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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> >
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                    In the wide-open spaces of NE Oregon