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      12-04-2012, 07:27 PM   #25
Brigadier General

Drives: 130i
Join Date: Nov 2011
Location: QLD, Australia

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Originally Posted by bradleyland View Post
You'd be amazed how many cars benefit from shifting before redline. This is especially true for turbo charged cars where the torque band comes on early. I've done plots on a couple of cars (one turbo, one NA), and both benefited from shifting before redline. The turbo charged one more so than the NA. Both were running stock ECU software.

Gearing multiplies torque, but it does not affect power. Peak acceleration will come at peak power. Engines like the S54 will work best when shifted at redline, but that's the exception, not the rule (for road cars).
yeah i know it's beneficial on MANY cars,

gearing still effects acceleration, if you have a 14:1 overall ratio and xxx HP, it'll accelerate faster than 13:1 and xxx+10 HP, until your HP drops way down closer to redline

even if power drops of WAY before redline, it's always beneficial to go a LITTLE past peak power, to the point a higher gear will accelerate you faster.

turbo cars SHOULD make peak power at redline, with anappropriate sized turbo etc.. as any power production should be overcome by pushing in more air.. cars like the N54, howeer, weren't designed from te start as racecar style, so the turbos can't push that far.

graphs of RB turbos show that peak power CAN be made at or near 7000rpm in the N54.. peak torque almost holds to there as well (but a huge hump a bit below 6)