Need help with Torque/RPM/Horsepower

[tia travels]

I'm confused when cars mention horsepower, RPM and torque. Below are 4 car examples. Some have high rpms with low horsepower and others high rpms with high horsepower. Same goes with the torque. What's better a car with low torque but high rpms or low rpms? Is the lower hp better with the high RPMs or the higher hp with lower RPMs? Why do the RPMs change between the torque and just the HP figure on the same car?

Which of the 4 cars below is most appealing to you based on these figures?
Which car is the fastest based on these figures?
Which car is the strongest?
When buying a car, which is better to compare? Torque or HP or RPMS?

CAR 1
207 torque@1700rpm --200hp@5100rpm
CAR 2
249 torque@4500rpm --263hp@6250rpm
CAR3
172 torque@4900rpm --182hp@6700rpm
CAR4
394 torque@4200rpm --363hp@5200rpm

[essence]

I would be more interested in MPG.

Torque is like measuring how hard you can turn a screw driver against a stiff screw.

Horesepower is like how much energy you put into it.

Or, to relate it to something else, torque is the size of the tool, horsepower is how vigorously you can use it. A large tool might get you started, but if it doesn't then raise it's game you will be frustrated when you scream 'fuck me harder'.

I wouldn;t worry about RPM - the gearbox takes care of that. Unless you are a spinner.

[1NEMESIS]

Originally Posted by essence

I would be more interested in MPG.

Torque is like measuring how hard you can turn a screw driver against a stiff screw.

Horesepower is like how much energy you put into it.

Or, to relate it to something else, torque is the size of the tool, horsepower is how vigorously you can use it. A large tool might get you started, but if it doesn't then raise it's game you will be frustrated when you scream 'fuck me harder'.

I wouldn;t worry about RPM - the gearbox takes care of that. Unless you are a spinner.

Good analogy, sometimes it's hard for explain the torque/horsepower question but you did a good job..

[essence]

To be more specific:

- torque is force time distance
- horsepower is power - in metric units it is joules per second, where joules is energy. So horsepower is the rate at which you expend energy.

If you run 100 metres in 15 seconds, you expend a certain amount of energy.
If you are Bolt, you expend a lot more energy.

So Bolt has more power.

I have no knowledge or experience or information concerning the amount of torque Bolt has.

But if you watch sprinters at the start of the race, their legs are all twisted.

That is torque.

The movement of their appendages at 80 m is no indication of their bedroom prowess.

As for me, I prefer to relate it to the women. The tightness of their ass as they bend over at the starting blocks is their torque.

The glistening thighs at the end of their 400m which you want over your ears as you take their clit in your mouth is their horsepower. It is their energy divided by their 400 time. 48 sec is better than 75 sec, more vibrancy to the thighs, but 44 sec may make you question their gender.

I like lots of torque and plenty of horsepower.

[1NEMESIS]

Here's a good visual of torque, you can see the twisting force of the trucks at the start of the race….http://youtu.be/Jxv2hOlFav4

[Rakhir]

Torque is also the application of the transfer of force. You have to be able to harness horsepower/energy and transfer it to the ground via transmission, driveshaft, differential and tires all part of the drive train.

Interestingly enough Nemesis' video is a great example of the application of torque to ground. You will see how the vehicles, lock up, as their drive trains engage and transfer their energy to the ground. This application makes no distinction between internal combustion or electric processes. Point of fact electric motors actually generate more torque in their application but are unable to sustain it due to the weight to power curve ratio of the energy needed to develop and maintain torque.

[Texas Contrarian]

Originally Posted by Rakhir

Point of fact electric motors actually generate more torque in their application but are unable to sustain it due to the weight to power curve ratio of the energy needed to develop and maintain torque.

Good point.

Here's an entertaining demonstration:

http://www.youtube.com/watch?v=pm6gD6r3-cw

Similarly, my Tesla Roadster Sport accelerates from 0-60 as fast or faster than many Porsches with much more horsepower. (The electric motor in the Tesla produces only 288hp.) It's great fun! But a Porsche Turbo would simply outmuscle it after a couple of gear shifts enable the engine to spend some time operating in higher-RPM ranges where it can develop close to its peak horsepower.

[tia travels]

These are all helpful explanations. That video was good too. Essence--your female comparison was interesting.

But I'm still unsure with the car examples above, which would be the best car engine wise. Are the ones with smaller torque the faster/stronger cars? I know with all the driving I do, I should be considering a car with good mpg, but...

What are folks' opinions on turbo engines in cars? Do they fall apart sooner than other types?

[Texas Contrarian]

Originally Posted by tia travels

These are all helpful explanations. That video was good too. Essence--your female comparison was interesting.

But I'm still unsure with the car examples above, which would be the best car engine wise. Are the ones with smaller torque the faster/stronger cars? I know with all the driving I do, I should be considering a car with good mpg, but...

What are folks' opinions on turbo engines in cars? Do they fall apart sooner than other types?

Tia, I'm not sure from your posts exactly what your highest priorities are. Dependability is apparently very important to you, since you are concerned about turbo engines. If you google a few terms such as turbo engine dependability or reliability, you'll get a lot of hits and can do some reading. Opinions may be all over the place, since a lot depends on the particular engineering involved in a given engine. But turbos obviously involve some additional complexity, and ask more in the way of power output from a fixed level of displacement (cubic inches or liters), so it's reasonble to expect that there could possibly be reliability concerns.

But the choice is essentially a somewhat subjective one.

I always liked the website www.howstuffworks.com.

You might enjoy this explanation of horsepower:

http://www.howstuffworks.com/horsepower1.htm/printable

[Rakhir]

Just for grins here are a few tidbits to amuse you on this topic of torque.

Top fuel dragsters are the ultimate expression in this area. They use 26 gallons of nitro-methane fuel in one run. The fuel lines are 1 inch to each cylinder. Basically the 1/4 mile they run is a controlled explosion. After each run they tear down and completely rebuild the engine and transmission. A top fuel car completely burns out 26-32 clutch plates in one run!

There are some other factors involved such as air density, temperature of track and tire pressure. Low pressures allow for greater frictional grip and transfer of energy and they lock down. Too little and you bog down as well so the proper balance has to be maintained.

If you were to stand halfway down the track and waited to see the top fuel car move before you tried to jump out of the way you would have already been hit! The current record time for a top fuel in the quarter mile is 3.7 seconds!
http://www.youtube.com/watch?v=64BCcNyAvxU

[CJ7]

Bypass the physics unless you pull heavy loads or race ... for normal city/highway transportation a wise man once said ..

I would be more interested in MPG

The best car anyone can possibly buy is the one they like the most, and dont mind paying for.

[Ansley]

Originally Posted by tia travels

What are folks' opinions on turbo engines in cars? Do they fall apart sooner than other types?

I don't know if a turbo will fall apart faster, but I do know that a car with turbo can be more expensive to insure. I hope you find a great car that you enjoy.

[1NEMESIS]

Originally Posted by tia travels

These are all helpful explanations. That video was good too. Essence--your female comparison was interesting.

But I'm still unsure with the car examples above, which would be the best car engine wise. Are the ones with smaller torque the faster/stronger cars? I know with all the driving I do, I should be considering a car with good mpg, but...

What are folks' opinions on turbo engines in cars? Do they fall apart sooner than other types?

Tia, what I would do is pick the cars you're interested and then do a net search and see if you can find breakdowns on performance, reliability etc and look for a consensus on what ever catches your eye, good luck and Happy Valentines Day!