Power (in horsepower) and Torque (in foot pounds) are always
equal at 5,252 RPM because of the English units conversion:
P = 2 * pi * n * T / 33000
Where n is RPM and T is torque. Since 33000 / (2 * pi) is 5,252,
they are equal at 5,252 RPM.
The peak torque can be before, at or after 5,252 RPM. It depends
on the engine. All the math says it that they're equal at that
point. But why worry about torque when it's power that really
matters?
The final step is to account for the fact that torque at the
wheel of the car is equal to the torque at the crankshaft
multiplied by the relative rotational speeds of the wheel and the
crankshaft. Of course that depends on your gear ratio and your
engine RPM -- which is obvious because we all know that you get
better accleration in 1st gear than in 4th gear.
In short, the higher RPM at which you get your torque, the more
acceleration you get. Power is torque multiplied by RPM.
Torque may give some guys hard-ons, but it doesn't by itself make
the car go fast. For that you need power.
Donald R McKenna wrote:
>
> >From: Dan Bratten <dbratten@ainet.com>
>
> >Doesn't torque max out -- and equal horsepower -- at 5,250 (5,750???)
> >RPM for all motors? If so, then beyond that RPM the motor only gains
> >HP and must rely on said HP to keep accelerating?
>
> My understanding is that torque and Horsepower cross at 5252 RPM in all
> motors (if they will spin that high). I think HP = Torque x RPM / 5252.
> Therefore at 5252 RPM they are equal. Most engines we mortals come in
> contact with will hit peak torque before 5252 RPM and be going down as the
> torque curve crosses the HP curve which may be going up or down at that
> point. However its possible, as in the case of the Honda S2000 (153 ft.# Tq
> @ 7500, 240 HP @ 8300) for the torque curve to cross the HP curve at 5252
> while still going up to max. torque @ 7500 RPM. BTW, the Honda's torque @
> 8300 is still 151.
>
> And I thought my LT4 low end was "dead" with peak torque at 4500 RPM.
>
> Don
--
Michael R. Clements
mrc01@flash.net
A government big enough to give you everything you want
is also big enough to take away everything you have.
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