372 hp figures

[kdhotsaw]

Hello tundraotto,
Sorry about the delay on your question on horsepower figures. the figures won't match on hp increase verses factory horsepower figures. when we say we get a twenty % power increase we really mean a 20% cutting decrease in a log. if the saw is stock as we recieve it we go out and cut in a given size log with a certain chain and record the cutting time. lets say the stock saw makes a 10 second cut, then we do our modifications, make a 8 second cut with the mods. now that is a 20% improvement. make more mods and it cuts at 6 seconds, that puts you up to 40 % improvement. I don't relie on factory horsepower figures. unless you know the rpm and torque figures it means nothing. horsepower figures are a calculation derived from a torque figure at a given rpm, the formula is
torque times rpm divided by 5252

10 foot pounds torque times 9000 rpm divided by 5252=17.1 hp

10 foot pounds torque times 12000 rpm divided by 5252= 22.8 hp
same torque figure at both rpms but different hp figures
Don,t worry Otto, when dennis gets your 372 modified and you run it you'll be very suprised at the power increase . you will blow the masden's and walker 372's away. may even get an occasional 066 stihl . you'll be cutting close to dennis's 2171 or my 372 husky. all you will need is some primo chain
ken kdhotsaw

P.S Dennis told me a couple of days ago your saw was as far as seattle

 

[Cicero]

What does the 5252 figure mean?

 

[HUSKYMAN]

5252 is the constant required in the formula. Some engineer or physicist discovered it 100 years ago and I take his word for it

 

[Harley]

Hi,


"Watts definition of horsepower involved a force in pounds, applied over a distance in feet, for a time of 1.0 minute. Therefore, to convert the rotational force of the crankshaft into horsepower, you must know the distance the free end of the 1.0-foot lever will go in 1.0 minute. That, of course, would be the circumference of a circle with a 1.0-foot radius multiplied by the number of crankshaft revolutions per minute." AUTOMATH Handbook, John Lawlor

The equation then looks like this,
HP=6.2831853*RPM*Torque

The result is in # ft/ Min

To convert to Hp, we devide by 33000.

Now, if we take 6.2831853/33000, we get 1/5252.

Which makes the equation look like this.

HP=RPM*Torque/5252


The quote explained it better than I could have.

P.S. You can't directly measure Hp. You need to figure out work done and the time it took to do it in, or Torque and RPM.


Harley

 

[kdhotsaw]

hp numbers

alright harley,
good explanation on horsepower. I had no idea where the figure 5252 came from. thanks for the explanation
ken

 

[Harley]

You're welcome

Harley

 

[tundraotto]

Hi KD and thanks for the explanation - read it clear as a bell now. All sounds great since cutting speed is what were all after right?! Im very excited about Dennis getting to work his magic on the saw and cant wait to try it out.

Take care guys!