wstar's Journal

wstar

So, to sum up the (perhaps obvious to some!) things I've confirmed from looking at gears lately:

Given the shape of all VQ horsepower graphs, the things that really matter in the end, once you've seen the data, is "How do the gear gaps relate to each other" and "what's my max speed in top gear". As long as the gear gaps get shorter as you go higher in the box, and you don't run out of top speed, you're winning by going to a lower rear end ratio in terms of area-under-the-curve on the HP-vs-Speed graph (subtleties about shift points/delays notwithstanding).

In both the 6MT case and the 7AT case (ignoring the useless 1st gear, anyways), the gaps do get smaller all the way up the gearbox. While both exhibit the same basic narrowing of the gap as you go higher, the 7AT has significantly wider gears at the bottom and narrower at the top, vs the relatively-stable profile of the 6MT's gears, meaning there's probably less advantage to extreme gearing in the 6MT (but it's still there).

The percentage change in gearing per upshift looks like this:

7AT: 35.1% -> 36.0% -> 30.9% -> 29.2% -> 13.8% -> 10.4%
6MT: 38.7% -> 30.1% -> 21.7% -> 21.3% -> 20.6%

Top speeds in top gear with various rear ends discussed above, assuming 275/35R18 and a 7500rpm redline:

7AT:
3.357 -> 220
3.692 -> 200
3.917 -> 188
4.083 -> 180
4.364 -> 169
4.636 -> 159
4.900 -> 150

6MT:
3.357 -> 214
3.692 -> 194
3.917 -> 183
4.083 -> 175
4.364 -> 164
4.636 -> 154
4.900 -> 146

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