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  #421  
Old 04-16-2007, 07:27 PM
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Hamster hahahaha.
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  #422  
Old 04-16-2007, 11:39 PM
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Originally Posted by Cyco View Post
The linear force at the contact patch comes from a torsion force at the wheel - where does this force come from if not the engine?
Ok of course the force comes from the engine and if you looked at it at any instantaneous point in time then you could say that the engine makes torque which is transferred by gears to the wheels. However we (people living in the real world) are not interested in an instantaneous point in time we are interested in how the system works over time (i.e when a given amount of time is included so that we can do actual work). When you look at the system like that then it is clear that the engine generates power at engine speed, that power is then brought to the wheels through the transmission where the angular velocity is (normally) reduced to the desired speed and the power produces a force at the contact patch to accelerate the car.

I guess it comes down to whether you want to think about it in a purely technical, instantaneous sense that has no meaning in the real world or if you want to think about the system as it actually does work over time as it would in the real world.
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  #423  
Old 04-17-2007, 01:07 AM
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Or we could just say we hit the ****en peddle and the mo fo goes hard..

I have herd about torque at the rear wheels being calculated, So where does that come if all the above moves the car without torque?.
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  #424  
Old 04-17-2007, 01:31 AM
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Originally Posted by SlickHolden View Post
Or we could just say we hit the ****en peddle and the mo fo goes hard..

I have herd about torque at the rear wheels being calculated, So where does that come if all the above moves the car without torque?.
Power includes torque...

I never ever said that this happened without torque...

I said it can't happen without power.
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  #425  
Old 04-17-2007, 04:41 AM
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Quote:
Originally Posted by hightower99 View Post
Power includes torque...

I never ever said that this happened without torque...

I said it can't happen without power.
Well what yuou've been typing and us reading is that it is POWER that defined acceleration and we were pointing out the error in that.

It is TORQUE at the wheel that moves the car and it is the application of that torque over time that is the power. Hence how it is actually MEASURED in teh "real world"
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  #426  
Old 04-17-2007, 09:03 PM
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Originally Posted by hightower99 View Post
Revetec: Try to understand Alastor's point. He isn't saying that in any given gear that peak wheel torque happens at peak power. He is saying that for any given speed peak power will allow for the greatest amount of torque to the wheels for that speed. He is completely correct.
You can feel your peak acceleration can't you? Drive your car. Then post here what RPM you can feel it the strongest. Is it at the point of RPM you have peak power or peak torque? Go on and try it.

Most cars I have driven (and having an automotive engineering background as I have, I have driven quite a lot) you can feel peak acceleration at the RPM that peak torque it at. Yes more work is being done at peak power, but the discussion is about torque and acceleration. Go and drive your car and feel it.
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  #427  
Old 04-17-2007, 09:35 PM
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Ok last time I looked at this thread (roughly page 19) theres was an arugument about what torque does and what Horsepower does............



It's still the same arguement, what is going on?
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  #428  
Old 04-17-2007, 09:47 PM
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Quote:
Originally Posted by hightower99 View Post
Power includes torque...

I never ever said that this happened without torque...

I said it can't happen without power.
But with as much as you say stay on the power side of things it would be nice if you went into the torque side of moving the rear wheels more..

Quote:
Originally Posted by The_Canuck View Post
Ok last time I looked at this thread (roughly page 19) theres was an arugument about what torque does and what Horsepower does............



It's still the same arguement, what is going on?
S.F.A
It's slightly moved away from before only slightly, It went from i think we all agree now that the power might be working hardest in high RPM but in the torque curve it will be the best for acceleration..

Now it's torque at the rears moving the car forward.
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  #429  
Old 04-17-2007, 09:58 PM
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Originally Posted by SlickHolden View Post
Why is a..
1992 VP Commodore faster then a...
1995 VS Commodore.

Both use the same V6 but the VS has it's upgraded internals for more power and better fuel economy, Both use the Same GM Auto's 4L60.. Both use the same live rear with same diff ratio 3.08..

Weight VP Commodore 1337kg.. VS Commodore 1372kg
Power VP commodore 127kw@4800Rpm 293Nm@3600Rpm.
Power VS commodore 147kw@5200Rpm 304Nm@3600Rpm.

I'd like the guys who know all about power to be able to answer this one, 20kw upgrade in power but only 11Nm Torque.
There times 0-100km/h are pretty large apart from the factory. Also 1/4 drag times also from factory.. Any question needed to be ask ask away.

It's not the last new Commodore to be slower infact they have all been more powerful yet slower since 88. Yes they pack on the weight, But big power increases Vs small torque upgrades gets you thinking.
Firstly the VS is revving higher to produce 147kW. This derives from better breathing. The torque curve is flatter due to better breathing at higher RPMs but the peak torque is much the same.

Look....Power and torque go hand in hand. As I have explained before, a tractor has huge torque but little power which provides very strong pulling power and no top speed. F1 cars have high power at high RPMs but suffer from from low down torque requiring them to be revved to high RPM and dropping the clutch to get them off the mark. Both extremes are no good for street use.

Best case is high flat midrange torque for fuel economy and pulling power and good breathing at top RPMs to provide best maximum power. We can all argue about which is better, but the truth is both are important for performance, economy and maximum speed. Higher torque is good for strong acceleration without the need for revving the engine so high, and in turn uses less fuel.

This is why we are seeing car manufacturers selling transmissions with over 6 gears now, to keep the revs down. If you keep the revs down then the power made at the lower RPMs decrease. So a good high flat torque curve is there to make the car drive instead of bog down. High power provides good rev range and top speed after the torque curve drops off.

There will never be a winner in this discussion as power is derived from torque and RPM. It's a bit like which car manufacturer is better between Holden and Ford etc. The trick to good acceleration, economy and drive ability is to provide a flat torque curve and not let the torque curve drop off to fast, so it provides a good power curve after the torque gets past its peak, which helps continue the acceleration and provides top speed.

Reverting back to my previous posts, the best way to drive your engine is to rev your engine to maximum power and change gears into maximum torque.
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  #430  
Old 04-18-2007, 12:31 AM
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Quote:
Originally Posted by revetec View Post
Look....Power and torque go hand in hand. As I have explained before, a tractor has huge torque but little power which provides very strong pulling power and no top speed. F1 cars have high power at high RPMs but suffer from from low down torque requiring them to be revved to high RPM and dropping the clutch to get them off the mark. Both extremes are no good for street use.
Torque and power are inseperable. In the tractor case it's pulling power is equal to the power that it makes, the massive torque is needed to make that power at the low RPM that the engine operates at. In the F1 case the low torque means the engine produces very low power at low RPM which is insufficient to accelerate the car with the frictional loads it has to overcome (not to mention the low inertia of the engine).

Quote:
Originally Posted by revetec
This is why we are seeing car manufacturers selling transmissions with over 6 gears now, to keep the revs down. If you keep the revs down then the power made at the lower RPMs decrease. So a good high flat torque curve is there to make the car drive instead of bog down. High power provides good rev range and top speed after the torque curve drops off.
actually 6 speed transmissions have been marketed so that you can hold the engine in the high RPM range of the engine.

Quote:
Originally Posted by revetec
Reverting back to my previous posts, the best way to drive your engine is to rev your engine to maximum power and change gears into maximum torque.
Yes you are right assuming that the ratio spacing is sufficeint to allow RPM to drop to peak torque when you shift from peak power...
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  #431  
Old 04-18-2007, 04:07 AM
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Quote:
Originally Posted by revetec View Post
Firstly the VS is revving higher to produce 147kW. This derives from better breathing. The torque curve is flatter due to better breathing at higher RPMs but the peak torque is much the same.

Look....Power and torque go hand in hand. As I have explained before, a tractor has huge torque but little power which provides very strong pulling power and no top speed. F1 cars have high power at high RPMs but suffer from from low down torque requiring them to be revved to high RPM and dropping the clutch to get them off the mark. Both extremes are no good for street use.
But it's still slower, The other day with my over 300,000km VP i gave it a video camera test to 100km/h.. It's not the normal VN-VP take off it's a little flat like a VS on take off it's out of tune a little to rich it is flooding on take off slightly but it still did a 8.7sec. When moving it's fine, But on take off i should stall it up. Ever since i got my exhaust done it's been a much faster car in the mid range and down low it's missing a touch.
Best way to test it is with a G-Tech or grab a Helmut and go to calder park:0.

Quote:
Originally Posted by revetec View Post
Reverting back to my previous posts, the best way to drive your engine is to rev your engine to maximum power and change gears into maximum torque.
I agree with that because it's better to rev it up just for that torque spot in the next gear...
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  #432  
Old 04-18-2007, 05:15 PM
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Quote:
Originally Posted by revetec View Post
Look....Power and torque go hand in hand. As I have explained before, a tractor has huge torque but little power which provides very strong pulling power and no top speed. F1 cars have high power at high RPMs but suffer from from low down torque requiring them to be revved to high RPM and dropping the clutch to get them off the mark. Both extremes are no good for street use.
Power is more important for tractors than torque (more power means that you can work faster). In any case, the torque produced is not that much higher for most tractors compared to high performance turbodiesel cars.
Regarding F1 cars, http://www.youtube.com/watch?v=twkiJkBA5bc

Quote:
Originally Posted by revetec View Post
Reverting back to my previous posts, the best way to drive your engine is to rev your engine to maximum power and change gears into maximum torque.
It is unlikely that it will provide maximum acceleration as maximum acceleration at any speed is in the gear where the engine will provide the most power. I'm sure this has been mentioned already though.
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  #433  
Old 04-18-2007, 05:38 PM
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Originally Posted by H12 View Post
Power is more important for tractors than torque (more power means that you can work faster). In any case, the torque produced is not that much higher for most tractors compared to high performance turbodiesel cars.
DeRoy RACING trucks for Dakar ...

800hp --- lots of power, comparable to F1
3100Nm .... kind of makes an F1's near 380Nm seem silly

"not much higher" ? What are you comparing ??
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  #434  
Old 04-19-2007, 06:55 AM
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Originally Posted by Matra et Alpine View Post
"not much higher" ? What are you comparing ??
500-600 Nm.
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  #435  
Old 04-19-2007, 07:41 AM
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Originally Posted by H12 View Post
500-600 Nm.
Stock medium range trucks are abotu 1000Nm.

Could you please update your profile to include your approximate location so we can identify the norm of the types of trucks you woudl see /
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