[SEL] horsepower formula

[Peter A Forbes]

On Wed, 15 Sep 2004 08:15:28 -0400, you wrote:

>Hi Jim,
>    100% correct--and MY BAD! Using the CORRECT formula my "16 HP Galloway"
>is 15.27 IHP and between 12.2 and 13.43 BTHP (the rpm's SHOULD BE 240--NOT
>225!) Using a divisor of 10,500 for the final calculation (even though it's
>a 4 cycle) provides a much closer estimation of what Galloway claimed for
>the engine. Perhaps I'll keep it after all!
>    Dave
>
>> Hi Guys,
>>  If I read the formula correctly, The area of a cyl is NOT 3.14x
> "D"[bore"]but 3.14  x R SQD.[RXR] Plug in the #'s and see if you come closer to the
>> advertised HP.   Cya,   Jimmy O'Hagan
>>
>> Jim O'Hagan

I haven't got Dave's Galloway cylinder dimensions handy to check his
calculations, but it looks like the result is pretty close. The 3.14 should in
truth be 3.142857 or 22 / 7, the value for pi.  That small discrepancy won't
make a huge difference but it's worth a mention.

The Royal Automobile Club (RAC) formula would be interesting to apply to Dave's
Galloway:

bhp= (d X d) N / 2.5  OR   0.4 ( (d X d) N)

Where d = cylinder diameter in inches, and N =  number of cylinders.

This was derived back in the early 1900's in the UK to provide a rating for tax
purposes, and is estimated at 1000 rpm and a bmep of 67.2psi.

Peter
  
--
Peter & Rita Forbes
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