Quote:
Originally Posted by sdhotwn
Here's some of the basic math without actual shift points.
Gear Ratios: 1- 4.11, 2 - 2.32, 3 - 1.54, 4 - 1.18, 5 - 1.00, 6 - .85
So a shift from 1st to 2nd... the torque at a given point in the rpm's would have to be 1.77 times greater for it to not to be a loss in acceleration. a 2-3 shift - 1.5X, for a 3-4 shift - 1.3X.
Attached is a graph of the torque dynos from the M3/M4 (assuming the CS uses similar tuning on the S55 to the ZCP and not the M3 CS variant).
Flywheel torque at redline is ~310 ft-lbs. The 3-4 shift has the smallest multiplier I listed putting you at needing about 403 ft-lbs to make even. It looks like you'd exceed this if drop back below 5000 rpm's. However, if you shift earlier, 7,000 rpm's torque is at 350 and you'd have to drop back to a torque above 455 ft-lbs, which doesn't exist (for the ZCP curve). I'm not spending the time to calculate with final drive etc what the actual rpm change is with the shifts either here, but I'm doubtful we are getting 2500+ rpm drop on a 3-4 shift to get you back below 5,000 rpm's anyway, so it further reinforces the situation.
So moral of the story is if you have the ZCP tune type curve in our CS, you shift at redline for maximum acceleration.
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Your the man. I guess that’s why it’s there eh! I need to install a shift light now. The rpm cluster is pretty tough to quick glance it without any red