Quote:
Originally Posted by minispeed
Why stop at 6, 8 speeds are plenty now and the 10s are coming.
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With a manual box on ~2-3L engines and smaller displacement high revving engines I think 5 close ratios + 2 standard wide spaced (that means like 0.7 ish) is good enough, a lot of the time the last gear on the automatic version is ~70% of the reduction ratio of the last gear on the manual transmission, so basically adding an extra gear to what manual boxes are now should bring a good 10-15% improvement in highway fuel economy on most cars.
With under like 160hp 6 is probably enough, shorten the first 5 a tiny bit and then use the 6th one to drop the revs down a bit more, maybe 10-20%. MT economy car gearing isn't usually all that bad, when you consider the requirement of being able to run up hills and against wind and stuff in last gear.
With large displacement engines 8 or more is good of course. Lambos with their 7 extremely close ratios on a 7L engine could use like 10 lol. I think they cruise at the typical rpms you find on 2L engines.