This is an automotive question.  In reference to "torque", and with
all else equal, which is preferable; 205ft-lbs@4800rpm or
227ft-lbs@3800rpm.  Can you explain the concept of torque in laymans
terms?

Hi!!

Read the following definitions:
"Torque is a twisting force applied to an object, like a wheel or a
crankshaft. Note that motion is not required for torque to exist! If
you stand on a lug wrench that is on a frozen lug bolt, you are
applying a torque to that bolt even though there may be no movement.
For our purposes, we will consider that torque is measured in
pounds-force feet (lbf-ft) meaning the equivalent of a given force, in
pounds, acting on the end of a lever of length in feet. For example,
standing with 180 pounds body weight on a lug wrench one foot long
yields 180 lbf-ft of torque. A child of 90 pounds standing on a
two-foot lug wrench applies the same torque.

Work is the application of force over a distance. Unfortunately, the
units used are the same (pounds times feet) but we write this as ft-lb
just to distinguish it. The real difference is that in this case, the
"feet" part means feet of movement. If you push on a car with 100
pounds of force and maintain that for 30 feet, you have done 3000
ft-lb of work. An easier example is lifting a weight (in pounds) a
given distance (in feet). If you use some sort of mechanical
advantage, like a winch, you will do the same amount of work because
by halving the effort required, you will have to double the distance
through which you apply the force to achive the same objective.

Power is the application of work within a finite time. 550 ft-lb of
work in one second is one horsepower."
From "Torque and Power":
http://www.largiader.com/articles/torque.html

Read this article, you will find it useful.


On a car's engine the torque is not constant, it depends on the
turning speed of the motor (rpm). Normally it initiates with a very
low torque, and increases gradually until reaching a maximum and then
it returns to fall. The power, being the result of the multiplication
of torque by the rpm, has a similar behavior although the maximum
power is reached to a greater rpm because although torque no longer is
in its maximum point it is compensated by the increase of the engine
speed, the power finally falls when torque is definitively very low
and it cannot be compensated by the turning speed of the motor.
From the driver's point of view, the torque is which actually push the
vehicle to accelerate it. Torque is what gives us the acceleration
sensation. Torque maximum is reached at the point of the tachometer in
where the acceleration sensation is maximum. If you want to tow a load
or to raise a hill, it is recommended to maintain the motor in its
turning regime of maximum torque. The power is not bound directly with
the acceleration of the vehicle, but rather, it is a measurement of
how much the acceleration or the sensation of push lasts. Once maximum
torque has been reached the vehicle begins to accelerate forcefully
until certain point in the tachometer in where the vehicle no longer
accelerates with the same intensity, the point in the tachometer until
which the vehicle manages to accelerate forcefully is the one of
maximum power. If you want to overtake a car in the highway it is
recommended to place a gear so that the tachometer falls in the
maximum torque point and then  accelerate until the point of maximum
power.

The answer to your question: which is preferable; 205ft-lbs@4800rpm or 
227ft-lbs@3800rpm? is not absolute. 
It depends on what do you need; if you want to move a heavy load from
low RPMs (like a truck) you will prefer 227ft-lbs@3800rpm, but if you
need a good response in a highway (sport cars) you will prefer the
maximum torque at higher RPMs, because the engine will work at high
speeds. Remember that the torque is what actually accelerates the car.


The following pages will clarify the point of what torque means in a car engine:
"Howstuffworks - How Force, Power, Torque and Energy Work - What is Torque?":
http://science.howstuffworks.com/fpte4.htm

"Howstuffworks - How Force, Power, Torque and Energy Work - Torque comparison"
http://science.howstuffworks.com/fpte5.htm

"Torque and Cars":
http://www.newton.dep.anl.gov/askasci/eng99/eng99128.htm

"ITV Motoring - Power And Torque Explained":
http://www.itv-motoring.com/features/technical/636.asp

And a little bit more advanced articles:
"Horsepower vs torque":
http://www.allpar.com/eek/hp-vs-torque.html

"Torque and Horsepower Explained":
http://www.epi-eng.com/BAS-PwrTrq.htm


Search strategy:
torque power engine
torque car


I hope this helps you. Feel free to request for a clarification if you need it.

Best regards,
livioflores-ga

This has been very helpful in trying to decipher the information given
about cars.  I'm in the market to purchase and was faced with info
overload.