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Horsepower
and Torque
This
month we will talk about torque and horsepower.
We all know that the more horsepower you have
the faster you will go. But what is horsepower
and torque and how does it relate to performance?
That is what we will discuss this month.
The
term horsepower was created by inventor James
Watt in 1775. James Watt was also the inventor
of the steam engine and is also famous for the
term watt as in a 100 Watt light bulb. He determined
that a strong horse could lift 150 pounds a height
of 220 feet in 1 minute.
Torque
on the other hand is a measurement of a twisting
force. This can be the twisting of a wrench, driveshaft,
tire, etc. Engine horsepower is calculated from
the engines torque.
We
measure an engines output on a dynometer or dyno
as it is commonly called. A dyno measures torque
by applying a load on the engine. As the engine’s
RPMs increase, the load is also increased. Once
the torque is found, the dyno program will calculate
the horsepower from there.
There
are two types of dynos, the engine dyno and the
chassis dyno. The engine dyno tests only the engine
without accessories, drivelines, etc. This is
the common rated horsepower that engine manufactures
and auto manufactures use. It is a good indication
of an engine’s output, but not of a vehicle’s
true horsepower.
A
chassis dyno will give a true indication of a
vehicle’s horsepower. The reason for this
is that the engine will have all the components
installed, alternator, power steering, etc. It
will also have the driveline installed. There
is parasitic loses with the engine accessories
and normal driveline loses. The chassis dyno is
the best way to get a true horsepower rating for
your vehicle.
Now
the question becomes, what is better: horsepower
or torque? It depends on the vehicle. If you have
a heavy vehicle, haul big loads, or tow, then
torque is what you want. For light vehicles or
race cars, horsepower is what you want. The reason
for having more torque is because torque is what
gets the vehicle moving. So the heavier the vehicle,
the more torque you need to get it moving. This
is why most diesel engines have very low horsepower
but tons of torque.
The
opposite is true on light vehicles. Although you
still need torque to help get the vehicle moving,
horsepower is what gets it moving faster. This
is one of the reason race cars need a push to
get going. The vehicles are rely on lower torque
at low RPMs to get them moving quicker. They just
don’t have enough torque to get the vehicle
moving fast enough.
Well
I hope this helps clear some information on horsepower
and torque. If you have any questions or comments,
please contact me at the below addresses.
CYA
next month!
Vincent Wright
sales@kmwperformance.com
http://www.kmwperformance.com
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