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Thread: Battle of hp & torque

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Posts: 21-30 of 57
2009-08-03 20:09:39
#21
Originally Posted by Ninety-9
To put it another way, Imagine an engine that produces a flat 200ft-lb torque curve from 2000RPM to 7000RPM. That means that at ANY RPM it takes the same amount of force to stop or slow the acceleration. However, it takes a lot more energy to stop movement from a higher RPM.


So what about cars that have full torque at say 1900 rpm. Is that a bad thing or a good thing. Or do you constantly want to build torque along with Horsepower?

Mini Cooper S comes to mind here with the max torque at 1900 RPM.
2009-08-10 05:28:02
#22
Originally Posted by Ninety-9
Well, to be technical, Torque is not a force, it's force x distance, or moment. Torque is what the engine puts out (an angular force), horsepower is is torque in relation to time (in this case, time/rotation), which is power. There are two reasons for this 1) angular velocity carries momentum 2) an engine running at high RPM produces more energy in a given time frame.
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Torque is a force. You can have 300lbs of torque on a breaker bar without ever moving the nut you are trying to move. HP is a mathematical equation of work being done. Torque isn't accomplishing anything until it causes work to be completed. Then you can calculate hp.

I can apply 300lbs of torque to a bolt for 6 hours. This is torque over time like you said. But if I don't cause any movement, then no work is being accomplished. HP is a measure of work being completed.

So you are half-right.

All things being equal, whoever has the highest average output over the rev range they are being operated at will win.
2009-08-10 05:32:19
#23
Originally Posted by Vadim
So what about cars that have full torque at say 1900 rpm. Is that a bad thing or a good thing. Or do you constantly want to build torque along with Horsepower?

Mini Cooper S comes to mind here with the max torque at 1900 RPM.


Dang, ben beat me to it.

Well, having a flat torque curve isn't as cool as having a flat hp curve. If you made a constant 200whp with an electric motor in your SEL it would be so stupid fast off the line you wouldn't know what to do with your tire carcasses. lol.

Having torque sooner means you will have more hp in that area of the powerband, thus accelerate faster. This makes the engine perform over a broad powerband.

I like to show my dyno graph because it is a perfect example of a horrible powerband. When I shift I lose about 80whp on the old setup. If I kept a constant 400whp flat from 5000-7500rpm then the car would be so much faster!
2009-08-17 20:23:32
#24
Now Coheed is that because when you would shift you would be outside of VVL?

Now the SR20DE NA torque band is a bit linear... Man it looks so weak!



Here is a T25 one. As you can see with higher RPM's the T25 just face plants in the torque department.
2009-08-17 21:32:30
#25
Originally Posted by danmartin
Uhh its really simple, torque means nothing compared to HP. HP is defined as the power required to move a mass over a certain distance over a period of time. Torque is a force, independent of movement.

In drag racing, you should never use the lower portion of the power band, most of the time is spent in high RPM. So a car with a stouter power band will win, regardless of torque.


you cant say regardless of torque can you? that would be saying a high horse power motorcycle engine could move our cars just because it has horsepower. torque it still required to get the car moving otherwise you would be sitting on the line...
2009-08-17 22:07:48
#26
Originally Posted by Ninety-9
Well, to be technical, Torque is not a force, it's force x distance, or moment. Torque is what the engine puts out (an angular force), horsepower is is torque in relation to time (in this case, time/rotation), which is power. There are two reasons for this 1) angular velocity carries momentum 2) an engine running at high RPM produces more energy in a given time frame.

Torque is the raw output, horsepower is the usable energy. Since they're directly related to each other, more torque means more horsepower. To put it another way, Imagine an engine that produces a flat 200ft-lb torque curve from 2000RPM to 7000RPM. That means that at ANY RPM it takes the same amount of force to stop or slow the acceleration. However, it takes a lot more energy to stop movement from a higher RPM.


Originally Posted by BenFenner
This is only true in a common internal combustion engine where it cannot produce any torque without moving. The practice of linking torque and power to each other is a common mistake from those who are used to internal combustion engines. You can have torque without producing any horsepower. Electric motors do this all the time.
And because of that...

This is only true for internal combustion engines because of their inability to continue running once stopped. Torque can be produced without producing any [horse]power. This is not some nit-picky thing. This concept is essential to understanding what roles each play.


Originally Posted by Coheed
Torque is a force. You can have 300lbs of torque on a breaker bar without ever moving the nut you are trying to move. HP is a mathematical equation of work being done. Torque isn't accomplishing anything until it causes work to be completed. Then you can calculate hp.

I can apply 300lbs of torque to a bolt for 6 hours. This is torque over time like you said. But if I don't cause any movement, then no work is being accomplished. HP is a measure of work being completed.

So you are half-right.

All things being equal, whoever has the highest average output over the rev range they are being operated at will win.


I dont have the time right now but this is not all accurate from a physics perspective.
2009-08-17 22:49:13
#27
Originally Posted by blk-nx2000
High horsepower at low rpm is still required to get the car moving otherwise you would be sitting on the line...
Fixed that for yah.
2009-08-17 23:45:54
#28
Originally Posted by blk-nx2000
you cant say regardless of torque can you? that would be saying a high horse power motorcycle engine could move our cars just because it has horsepower. torque it still required to get the car moving otherwise you would be sitting on the line...


I'm saying a high horsepower motor cycle engine would move "your" cars. Torque doesn't translate to movement.
2009-08-18 03:07:31
#29
so you guys are telling me a 200hp .6 liter w/ little torque will move the car just as fast as a 200hp 2 liter with moderate torque? something seems a bit wrong here to me... or am i missing something?
2009-08-18 03:27:55
#30
That sucks my t-25 made 250tq and 230whp soo does that mean I'm special since my tq didn't fall on its face?


Here is a T25 one. As you can see with higher RPM's the T25 just face plants in the torque department.
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