05-12-2018, 09:38 PM | #57 | ||
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Quote:
How sure are you that there was no wind at all? You're talking about differences of 0.01s, even a tiny little bit of wind can make that difference. Quote:
Do five 4th gear pulls on the same road back to back and you'll have a much better sample set to look at.
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05-12-2018, 10:12 PM | #58 |
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I'm not entirely sure his car can reach the top of 4th gear with his fd... I usually use 3rd gear and find it adequate for logging. Not as good as 4th, but isn't an excessive speed up top for a highway.
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05-12-2018, 10:35 PM | #59 |
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wparsons: and in your example i'd double those 4th gear runs to be performed in both directions. Exactly to cancel out possible wind impact.
But also yes, 4th gear is a bit excessive, at least on public roads. From memory when i recently was on track where at end of longest straight i for first time was able to redline 4th, speed IIRC was 170-180kmh on speedo. Speeding ticket at such might be .. a bit on costly side |
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05-12-2018, 11:06 PM | #60 |
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Same here. With 4.1 FD I think the top of 4th is over 105mph. Not trying to get a felony just for the sake of logging.
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05-13-2018, 12:21 AM | #61 |
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My offer to check your math stands.
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05-13-2018, 12:37 AM | #62 |
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He means it. Checking math is like porn to him!
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05-13-2018, 01:00 AM | #63 |
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05-13-2018, 01:07 AM | #64 | |
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Quote:
Last edited by nikitopo; 05-13-2018 at 01:31 AM. |
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05-13-2018, 01:25 AM | #65 |
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Math do not lie, but you have to model the problem correctly. You asked twice about total weights and diameters. A total weight and diameter is enough ONLY for the solid pulley. On the OEM pulley you have two different pulleys the one inside the other joined together with a rubber. You need the diameters of both and the weights of both. No one can really provide these numbers, unless someone takes apart the pulleys and measures the two weights. Then you have to create a model that the inside pulley is rotated by the center hub and the outside pulley is rotated by the inside pulley. With such model you would find that the rotation inertia is MUCH BIGGER and it not only relevant to the weight difference. As said before it is a complex problem and there are unkonwns in the equation (i.e. the weights of the OEM pulleys). It is much easier to make some measurements and see how the car behaves with standard tools like the virtual dyno app.
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05-13-2018, 01:38 AM | #66 | |
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Quote:
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05-13-2018, 01:40 AM | #67 |
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Have you ever done this kind of modeling? Because you sound just like someone who has read enough to talk about it but have no practical experience.
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05-13-2018, 06:44 AM | #68 |
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Of course I have done this many times and published results in scientific journals. It is very common when you are modeling a problem mathematically to verify somehow your conjectures or even have an expert from another area that will check the results and tell you if they make any sense or not. There exist even journals that will not accept any theoretical model without additional practical evidence or some kind of application.
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05-13-2018, 10:37 AM | #69 |
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05-13-2018, 10:53 AM | #70 | |
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Quote:
A heavier vehicle takes more energy to accelerate to a given speed as a lighter vehicle. If that acceleration is over the same period of time, the heavier vehicle will have had greater power applied. Virtual dyno probably starts with the acceleration numbers and back calculates the amount of energy that must have been put into the vehicle using the kinetic energy model. If your mass is off, your power output calculations are off. |
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