Quote:
Originally Posted by mao
Kato,
Most people assume WOT to be max power. This is not true as rpm is only one derivative of actual torque.
There can be area above the graph as well.
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Area above the curve is infinite.
Mao, go pick up a mathematics text book and understand what area under the curve means. It is not a car/dyno term.
Anyone who has studied intro to calculus in year 11 will know what an integral is. When people refer to the area under the curve, they are in fact referring to the integral of the torque curve.
Stolen a pic from wikipedia:
The blue shaded area is the area underneath the curve (ok so is the yellow, but hey a dyno graph won't cross the axis so let's ignore). What you want to do on a dyno is maximise this total area. Usually if you have a more 'rectangular' shaped torque curve there is more total area than a peaky 'triangle' shaped torque curve. Again the earlier the curve starts producing a maximum and the longer it holds on till it tapers off provides the maximum area.
The integral of torque with respect to angle (which you can convert from rpm) gives you work. Maximising work is the name of the game.
Quote:
Originally Posted by mao
As mentioned, rpm is just one derivative of torque.
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Incorrect. Please understand what a derivative is.
Quote:
Originally Posted by mao
A lot of guys talk about lag and torque especially on a WOT graph. A WOT graph tells you less than 10 percent about how a vehicle will perform.
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I would disagree. A dyno plot will tell you 90% of how a vehicle will perform. Applying the dyno plot knowledge to the track in question (whether it be drag, road, rally or circuit) will show you how the vehicle will perform. A true driver will use the data from the dyno to know when to shift to maximise the vehicle. A hack will rev a car out to 8,000rpm because that is the maximum rpm shown on a dash and then change gear into the wrong section of the torque curve.
If I am going to the drags, knowing approximately what rpm max torque is at and where it tapers off defines my shift pattern. Same principle for which gear to select coming out of a corner on a track.
Quote:
Originally Posted by mao
torque * RPM * 1/5250 = hp
I am tempted to post here. Will post up some formulaes on the dyno thread during the week including injector calculations etc.
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This formula only applies to torque measured in ft-lb. Most of us prefer torque in Nm so the following will apply:
Power (kW) = [Torque (Nm) x RPM] / 9549
Quote:
Originally Posted by mao
You can achieve more torque at a different load other than WOT. That is area above graph, even in the same gear.
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I would be surprised to see a vehicle tested in the same gear providing more torque at partial throttle. This just doesn't make sense to me. A dyno is setup to read 1:1 gear ratio's. Changing to other gears on the dyno will produce different results, but when you calculate the gear ratio back, it ends up pretty similar.
Yes I know when you look at a trace of a map there are many different cells that get used depending on throttle position/car load. A correctly set up dyno should still simulate the maximum for the car. If you are making more torque at 50% throttle, there is something very wrong.