onefastv6

this has probably been asked 1000 times but whats the difference? which does what? whats more important?

chrisc

this is actually a really great question that is asked a lot, but it not answered much further than "you need both of them" pretty much because giving the difference is hard to explain without some level of physics...lol...but i will try anyways

power = work / time

torque is a rotational force ( torque = force x vector of rotation)

pretty much torque can be explained as the "push in the wheels" while power would be the amound of work that can be done over a period of time


so both are equally important, you can have a lot of work that can be done, but if there is no "push" then nothing will really get done.
for example, there are a lot of japanese cars that have high horsepower, but so little torque that they will never catch up with another car with a much lower horsepower, but a greater torque


ps. sorry for how vague this is, i have never really attemeted to explain what each of these are out side of "class time"

undefeated

A lady at my job that used to race formula cars told me that torque wins races, not horsepower.

The way I understand it is torque is what gets you going, you know, from a stand still[sm=gears.gif]. Horsepower keeps you going, usually in the higher RPM's.

chrisc

alright after reading a bit more, i have found this

power = torque x angular speed
(in this situation:
angular speed is the RPM
power is the instintanious RWHP, meaning the amount of horsepower going to the ground at the moment)

so you could see this as:

(instintanious RWHP) = torque x RPM

so if you have a high amount of torque and the RPM is high, you are going to have a good amount of RWHP at the moment

however, this does not mean that the amount of maximum instintanious RWHP is defined by the amount of torque you have, it end somewhere at your max HP, so you also need to have a high amount of available HP


hope that clears it up a bit better

BlueStang6

Just one more way to look at the subject. Many times, people refer to a car that accelerates quickly at low speeds as having lots of low-end torque. However, lets look at two examples. Car A has an engine that generates 300 ft-lbs of torque at 3,000 RPM and Car B has an engine that generates the same 300 ft-lbs of torque at 4,000 RPM. Lets say that each car is geared so that the engine is making its maximum torque at 10 MPH. If you do the math, Car A requires 23.2:1 gearing (equal to the 1st gear ratio multiplied by the rear end ratio) to turn 3,000 RPM at 10 MPH (assuming a 26" diameter tire). Car B requires 33.3:1 gearing. The amount of torque applied to the rear tires is calculated by multiplying the engine torque by the overall gearing. Car A is driving the tires with 6,960 ft-lbs of torque and Car B is driving it's tires with 9,990 ft-lbs of torque; both at 10 MPH. In this case, at 10 MPH Car B is applying 43.5% more torque to the rear tires (and 43.5% more accelerating force to the ground) WITH THE SAME ENGINE TORQUE! What's the difference between the two cars in this example? Power (as defined by ChrisC in his posts) and gearing! Even though the two engines produce the same maximum torque, the fact that Cart B produces it at a higher RPM means it's making more power. If you can gear the car properly, the car making the most power (all other things being equal) is going to accelerate more quickly (at all speeds) and is most likely to win. So the short answer to your question is - you need them both - horsepower is how fast you hit the wall, torque is how far you take the wall with you!

blackfoot

torque gets you moving, horsepower maintains it

blackfoot

through gearing in 1st we put around 1800 ft/lbs to the ground, thats why dynos do the runs in 4th, 4th gear is a 1:1 ratio, 4th gear gives you the closest hp and torque numbers to the ground relative to your engine output

noir

Horsepower is how fast you can hit a wall. Torque is how much of the wall you take with you when you hit it

mtbker29

Interesting I glad this topic was posted.

CainMotorsports2102

good topic. dont forgetto mention that HP=TqxRPM/5250(constant)

I wonder why the constant is 5250?