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Old 10-01-2018, 09:38 AM
bmwman528e bmwman528e is offline
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Quote:
Originally Posted by bcredliner View Post
Not all E53 diffs are plug and play.

Why do you plan to go from 3.91 to 3.64 or 3.15 diff ratios?
For a boosted application the longer the gear the better within reason. With a 3.91 and a 4 speed 4l80e the rpms will be relatively high at freeway speeds etc. If this was a 6l80e trans maybe the 3.91 would be a good setup. At 80mph in overdrive with a 3.91/4l80e you will be turning 2700RPM. With a 3.15 you are at 2200RPM.
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