How do I calculate Torque?
 

What is the calculation for torque?
I know the Horsepower is:

HP = Torque(lb-ft) * RPM/5252

But how do I get Torque?

Let's see if I have had enough coffee....

If HP = T * (rpm/5252) then you could divide both sides by (rpm/5252)
and maybe end up with

T = HP/(rpm*5252)

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

AChevyFan wrote:
>
> What is the calculation for torque?
> I know the Horsepower is:
>
> HP = Torque(lb-ft) * RPM/5252
>
> But how do I get Torque?

Crap that should be

T = HP/(rpm/5252)

Need more coffee...

Mike

Mike Romain wrote:
>
> Let's see if I have had enough coffee....
>
> If HP = T * (rpm/5252) then you could divide both sides by (rpm/5252)
> and maybe end up with
>
> T = HP/(rpm*5252)
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> AChevyFan wrote:
> >
> > What is the calculation for torque?
> > I know the Horsepower is:
> >
> > HP = Torque(lb-ft) * RPM/5252
> >
> > But how do I get Torque?

If you have a known HP and RMP simply insert them into the formula you gave
and solve for torque. Otherwise, torque is something that must be measured
on the dyno. It would take a rather complex formula involving many
variables for you to calculate it.

"AChevyFan" > wrote in message
...
> What is the calculation for torque?
> I know the Horsepower is:
>
> HP = Torque(lb-ft) * RPM/5252
>
> But how do I get Torque?
>
>

AChevyFan wrote:

> What is the calculation for torque?
> I know the Horsepower is:
>
> HP = Torque(lb-ft) * RPM/5252
>
> But how do I get Torque?
>
>
Devide the horsepower at any rpm by that rpm value. The value of peak
torque may NOT be at the same rpm as peak HP, so you cannot compute peak
torque by dividing peak hp by rpm for peak hp. However, you can get the
torque at THAT rpm by dividing hp by rpm at the rpm for peak hp. It just
may not be the PEAK torque (which usually appears at a lower rpm).

In other words, you really need a curve of hp vs rpm to derive torque.
In fact, usually the dyno outputs torque vs rpm and you derive
horsepower by multiplying torque and each rpm. At least, that is the
way it used to be. Modern computerized dynos output curves of both,
doing the multiplication for you.

That's a great algrebra lesson but I am assuming that I have neither HP nor
Torque to calculate so that doesn't help me.

"Mike Romain" > wrote in message
...
> Let's see if I have had enough coffee....
>
> If HP = T * (rpm/5252) then you could divide both sides by (rpm/5252)
> and maybe end up with
>
> T = HP/(rpm*5252)
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> AChevyFan wrote:
> >
> > What is the calculation for torque?
> > I know the Horsepower is:
> >
> > HP = Torque(lb-ft) * RPM/5252
> >
> > But how do I get Torque?

Which is precisely why I am asking...thnx.


"Loren Eggert" > wrote in message
...
> If you have a known HP and RMP simply insert them into the formula you
gave
> and solve for torque. Otherwise, torque is something that must be
measured
> on the dyno. It would take a rather complex formula involving many
> variables for you to calculate it.
>
> "AChevyFan" > wrote in message
> ...
> > What is the calculation for torque?
> > I know the Horsepower is:
> >
> > HP = Torque(lb-ft) * RPM/5252
> >
> > But how do I get Torque?
> >
> >
>
>

You have to have one or the other to come close or go to a speed shop
that tests them on a dyno. Math and the real world seldom match up.

Mike

AChevyFan wrote:
>
> That's a great algrebra lesson but I am assuming that I have neither HP nor
> Torque to calculate so that doesn't help me.
>
> "Mike Romain" > wrote in message
> ...
> > Let's see if I have had enough coffee....
> >
> > If HP = T * (rpm/5252) then you could divide both sides by (rpm/5252)
> > and maybe end up with
> >
> > T = HP/(rpm/5252)
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > AChevyFan wrote:
> > >
> > > What is the calculation for torque?
> > > I know the Horsepower is:
> > >
> > > HP = Torque(lb-ft) * RPM/5252
> > >
> > > But how do I get Torque?

Torque = moment of intertia x angular acceleration

It would be explained in a college physics text.
That's where I'm looking at it.

You can calculate the monent of interia of a flywheel and calculate the
torque needed to get it accelerating at a given rate but trying to
calculate the moment of interia of the whole driveline including
transmission would, I imagine, be quite difficult. As mentioned it would
better be done by measuring resistance on a tread mill.

"AChevyFan" ) writes:
> What is the calculation for torque?
> I know the Horsepower is:
>
> HP = Torque(lb-ft) * RPM/5252
>
> But how do I get Torque?
>
>


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William R Watt National Capital FreeNet Ottawa's free community network
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Get a mechanical engineering degree with emphasis on thermodynamics.
You will learn this in your 4th year thermodynamics classes.

Erich

"AChevyFan" > wrote in message
...
> What is the calculation for torque?
> I know the Horsepower is:
>
> HP = Torque(lb-ft) * RPM/5252
>
> But how do I get Torque?
>
>