Re: [DMCForum] Re: Help, Andrei's Fallen Into the HP Trap [Slightly T]

[Jim Strickland <ihaveanaccount@xxxxxxxx>]

Time for some new words, bill.

You say that 300 horsepower engine can be more powerful than a different
300 horsepower engine.  Obviously you are not measuring how 'powerful'
something is with horsepower.  What are you measuring?

The car could tow the trailer if geared correctly; the same reason that
the mack truck with 400hp will never be faster than a 60hp civic.  



On Mon, 12 Jan 2004 21:22:31 -0000 "content22207"
<brobertson@xxxxxxxxxxxx> writes:
> Andrei, Andrei, Andrei -- don't fall into the HP trap. 
> 
> Horsepower is calculated from 2 numbers: Torque and RPM's. An engine
> that "only" produces a couple hundred HP, but does so at low RPM's, 
> is
> MUCH more powerful than an engine rated even higher at high RPM's.
> 
> Consider a semi trailer tractor. "Only" puts out 300-400 HP. But it
> does so at 1,500 RPM. Do you suppose your Porsche -- with the same 
> HP
> rating -- could pull 80,000 lbs as that tractor does? The answer is 
> of
> course "no" because it would never be able to rev anywhere near its
> power band (actually it would stall the minute you let the clutch 
> out).
> 
> Domestic big blocks have tremendous torque -- 3 or 4 times as much 
> as
> a little sports car engine. That's why you see people towing boats 
> and
> trailers with a Cadillac, but never a Honda.
> 
> FYI: HP = Torque x RPM / 5252.
> 
> The 450 HP rating of your 454 is probably a gross number, calculated
> out of the vehicle with no accessories on the front. That's the way
> American manufacturers did it in the 1960s. Actual net HP in the car
> averaged a hundred ponies or so lower. Domestic manufacturers 
> switched
> to net HP ratings at the same time they dropped compression ratios 
> --
> lower compression does lower HP, but not as badly as the 1972 
> numbers
> make it appear.
> 
> If you're having problems with the 454 in your boat, consider a Ford
> 460. I know it's a popular marine application.
> 
> Bill Robertson
> #5939
> 


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