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08-31-2014, 10:00 AM | #221 | |
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08-31-2014, 10:16 AM | #222 | ||
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As far as trap speed goes, isn't that more dependent on engine power than outright shift speeds? At least not a major influence? |
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08-31-2014, 01:16 PM | #223 |
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I would guess that shift speed will make a difference. There are two shifts in an F8X over a ¼ mile run, hence a DCT car spends .4~.8 seconds more time accelerating than a 6MT. That is certainly worth a few mph. This probably could be demonstrated through simulation.
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08-31-2014, 03:38 PM | #224 | |
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Or am I missing your point here? EDIT: Since the car doesn't stop during a shift but keeps rolling towards the finish line, the 0,2s difference, doesn't necessarily mean it spends just 0,2s less time accelerating. A average manual shift is probably around 0,3-0,4s. R&T compared a MT with a paddle shift and found that each gear change took 0,37s on average (in that car) and dropped 0,9MPH on the paddle shifted car. http://www.roadandtrack.com/go/news/...hift-gearboxes |
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08-31-2014, 08:50 PM | #225 | |
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Let's assume that, as you stated, the DCT equipped M4 is 0.2 sec faster through the quarter mile compared to the 6MT, so the DCT has 0.2 sec LESS time to accelerate. However, since the manual car needs to shift twice over the quarter mile run, it stops accelerating twice for a period of 0.3~0.4 sec each (the time it takes to execute the shift). The DCT does not stop accelerating during the shifts so it gains back 0.6~0.8 sec of acceleration time. According to the R&T article, the 6MT M4 needs 2.1 sec to accelerate from 110 to 120mph. Hence the 0.4~0,6 sec of additional acceleration time that the DCT gets is worth 2~3mph. It is that additional speed that allows the DCT to cross the line 0.2 sec before the 6MT... (that 0,2 sec at 117mph is worth about 30 feet, that is considerable). |
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09-01-2014, 12:27 AM | #226 | ||
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This also points to one other significant advantage that needs to be accounted for when using simple trap speed calculators online. I'm not sure they are set up for 80ms shift times...? IIRC the OP didn't want to share which shift times they used in their simulation... That is a point I haven't really thought to much about, but it might be a factor that will influence simulation results. |
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09-01-2014, 05:50 AM | #227 |
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The OP refrained from posting the shift times they used earlier in the thread, but, IIRC, they later posted they used 50ms. Since in a simulator, the shift time represents the period of time when acceleration is interrupted, I believe that a shift time of 0ms should be used for DCT.
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