Quote:
Originally Posted by upsidedownfunnel
Quote:
Originally Posted by OverDrive
The sad thing is it shows the redline is lower than S55. That sucks
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Any engine mated to a torque converter auto will have a similarly low redline. Torque converters deform when they spin too fast. That's why some performance cars have lower a redline when mated to an automatic. That's also why I'll be interested to see what the redline of the M3 Pure 6MT will be. |
The torque converter is locked at higher rpms; so there is no slippage. The lock-up clutch physically links the impeller and turbine with the TC, effectively changing the TC into a purely mechanical coupling.
There is no deformity, as you say. When the TC is slipping (is not locked) the limiting factor is heat build up. Programming of the TC stall speed is used to control heat build up and driveability.
What you're referring to is a ballooning effect from centrifugal forces within the TC at very high rpms. I doubt a 7600 rpm is cause for excessive ballooning. The VQ37HR in Nissan/Infiniti applications revs to 7600 with a standard TC equipped 7 speed auto.
BMW's turbocharged inline 6s are all about low-end grunt and rapid spool times. The emphasis, good or bad, has moved away from high rpm excitement to savage low end thrust......really has nothing to do with rpm limitation on the 8HP series ZF transmissions.