Can someone explain the difference between torque horsepower, and their relation to speed for cars?

Question

Can someone explain the difference between torque horsepower, and their relation to speed for cars?

Answer 1

Torque is the twisting force (turning force) to rotate an object about an axis. In other words, it is the force that makes things turn and "things" include wheels.

Power is the rate of doing work, or the rate at which energy is transmitted.

The relation between power and torque is:

Power (HP) = (torque x RPM)/5252 where torque is in foot pounds.

Let me know is you want the relationship in SI units.

Summarizing, it is easy to observe that higher torque means higher power. How this power is converted into speed will depend on the transmission mechanism of the individual vehicle, so no explicit formulae exist. You can set the transmission for high speeds, but then its acceleration will be sluggish. Or you can set it for high acceleration at the expense of top speed values.

That is where the engine technology in F1 is so wonderful, it is the delectable blend of high speed and phenomenal acceleration.

---------- ------------- ------------- --------------- --------------- -----------

Edit for EyesIn... : Nice illustration there, but I am afraid that the jet's sluggish acceleration is mainly due to its massive inertia. I've not seen the video, but a medium weight jet weighs upwards of 15 tons, thats atleast 25 times the F1 racer's weight. It takes a lot of energy to move a 15 ton object.

Why it gains speed? The secret is that the wings start developing lift as the jet accelerates. This brings down the effective weight and at about 170 - 200 kmph, any self-respecting jet would be ready for lift off. Or in other words, the weight on wheels is virtually nil and the thrust is high. The F1 racer's situation is just the opposite, its aerodynamics increases the downforce effectively putting more stress on the wheels. The combined effects of this mismatch is the unexpected overtaking at the end.

Answer 2

If you can lift 100 kgs and the next guy 50 you're twice as strong.

That's torque.

If he can lift 50 kgrs 4 times as fast as you can do 100 he's twice as powerful as you.

That's power.

If you are looking to knock someone out with one punch it has to be a good one.

If you are not strong enough for that but can land 10 punches on his face in a couple of seconds you can do the same job or better.

Horsepower depends on torque, but speed directly depends on power.

An F1 car doesn't have a lot of torque, it's engine doesn't produce lots of work, but it's d**n powerful because it does it's work in very little time (high reving),so that's what counts at the end of the day for speed, power.

Answer 3

It is wrong to say that more HP is more speed. The M1 Abrams battle tank has over 1500 hp but a top speed of only 40 mph. Firefox is right in saying that speed depends on how the power is transmitted to the wheels. More torque and higher revs means more HPs

A 1999 Suzuki Hayabusa with 151 HP could hit 320 kmph, which is close to the top speed of a F1 car in a racetrack.

Answer 4

are you talking about the differance between horsepower and torque or brake rated horsepower.there is a differance between crankshaft horsepower and crankshaft torque and brake rated horsepower and transmission output torque.there are formulas to find out the peak torque and peak horsepower minus drag by the transmission,aerodynamic drag and tire resistance.in the instace of land speed cars,torque will get the car going up to a point,horsepower will push you past the aerodynamic,final drive ratio and tire drag resistance.

Answer 5

The most simple way to describe the two is:

Torque is the energy (power) need to move the race car.

Horsepower determines of how fast it can be done.

Race cars need a balance of both

Answer 6

These are very basic examples of the two;

Torque- when the wheels brake lose from the pavement, (when someone does a power brake, burn out, hole-shot, ect.) is what torque is.

Horsepower- say your driving down the road, and your cruising down the road at 50mph. You put the pedal to the floor and feel the engine rev and the car starts to pull. This is horsepower.

while horse power is related to the "speed of cars", gear ratios actually have more to do with a car's top speed to a certain degree. More or less Horsepower makes the car achieve the top speed slower or faster depending on how many Pony's you have underneathe the hood.

Think of a bicycle. A BMX bike has 1 gear ratio (2 sprockets) and a maxium speed for that gear ratio which can be reached quicker, but a slower top speed. A Mountain Bike has many different gear ratios depending on how many gears or "speeds" the bike has which allows a mountain bike to actually travel at a higher top speed, but they have slower accelleration when compared to a BMX bike.

hope that helps

Answer 7

At a place like Richmond, you need torque to get off the corner and accelerate the car. You need horsepower at the end of the straight to reach your top speed. Notice that many street cars today have more torque than hp. Torque=acceleration. HP= top speed.

Answer 8

It also has to do with how much gas they use and how they use it in the engine.

Answer 9

great technical answers above, so i will give you a good illustration instead, the f1 Vs the fighter plane, they seem to do this 2 or 3 times a year, and this race is really a horse power Vs torque demo

they drop the flag and both max out the throttle, the f1 car with 700 hp and i don't know the rated torque but I'll bets its close to the 700 side of things leaves the jet in its dust, being a jet engine has around 30-50 thousand horse power but little to no torque, the fighters starts with a crawl,  the f1 car is past half way before the jet makes it a quarter of the way down the run way,   the jet is picking up speed but judging by the gap the race car is going to win for sure right? no on the last 20 feet the jet closes the gap to beet the Ferrari by a nose, its always how it finishes,

so how does a race car compete with a jet capable of mach 1.5? as the f1 car applied far greater torque it launched off the line but was maxed out on top speed before it reached half way, where the jet started slow but by the time it reached the finish, it had barley gotten started and was only using about 5-10% of its total speed

torque Vs hp