[AT] Horsepower Question

[carl gogol]

Dave-
I only check personal email once a day so I am a bit slow in answering.
In order to control end cost, the cooling of these small lawnmower engines 
are not designed for cooling more than the average anticipated load.  The 20 
HP rating is for peak horsepower, which it might be able to produce for a 
few minutes without the engine getting too hot.  However, if you run it 
continuous at the peak HP its temperature will quite rapidly rise past the 
design temperature limit.  At that point it is just getting worse faster as 
the temperature goes up the oil breaks down and the friction increases and 
....
To produce peak HP you are requiring a higher throttle setting than the 
continuous load rating in order to get more fuel into the cylinder -- which 
produces proportionally more waste heat.  These engines might be able to 
continuously provide 10 HP (maybe less) because usually no more than that is 
needed.  There is enough mass in the block to absorb additional heat for a 
short period, but then the block's temperature starts to rise fast due to 
its limited cooling area.  No problem for a short period, but continuous 
full production at maximum short term rating will cause failure due to 
temperature induced bearing and piston failure.  They are aluminum after 
all.  If you want to try this, do it on a real cool day because on a hot day 
it will be over quickly.
Carl Gogol - Manlius, NY
Tasty grazing in the Oran valley of Central NY
AC D14, 914H
JD 5320 MFWD
Kubota F-2400, B7300HST

----- Original Message ----- 
From: "David Rotigel" <rotigel at me.com>
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
Sent: Wednesday, October 06, 2010 8:09 PM
Subject: Re: [AT] Horsepower Question


> Hi Carl, Why would that be the case?
> Dave
>
> On Oct 6, 2010, at 7:26 PM, carl gogol wrote:
>
>> If your lawnmower engine had to actually produce 20 HP for an hour
>> it would
>> probably melt
>> Carl
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