Nick's comments about the GM 5.3 being "gutless" (at least off the line) reminded me of something: torque management. I recall the 5.3 getting some flack from the 5.7 guys who claimed the 5.7 had more low end torque; but it appears that GM upped the TQM at some point with the 4L60/65. [I also recall some guys turning it off, via tuners.] Some poking around (see this thread ) indicates the 4L65 was 380ft-lb input torque and 680ft-lb output. In 1st gear (3:1) that means less than 230 peak allowed; that can be what, 25% reduction on the early 5.3's, and a third on the later ones?
Novak indicates the later 6L80 is 440 max input and 664 max output. Torque management still has to be used (although the 2:1 second gear probably near-full torque once in second). [The 6L90 allows 885 max output.]
Strikes me as odd, but it probably makes some sense: once past a certain torque output, a truck (or even SUV) becomes traction limited. Other driveline parts might not be rated for much more toque. And once out of first gear, full torque is allowed.
So I guess my question is: do the other transmission makers (Ford, ZF, etc) have similar limitations, where max input torque can exceed max output torque when in first gear?
[Heck--I almost forgot--a torque convertor can get upwards of 2:1 torque multiplication. That's not near max torque of the engine, but it's gotta be a factor too.]
Novak indicates the later 6L80 is 440 max input and 664 max output. Torque management still has to be used (although the 2:1 second gear probably near-full torque once in second). [The 6L90 allows 885 max output.]
Strikes me as odd, but it probably makes some sense: once past a certain torque output, a truck (or even SUV) becomes traction limited. Other driveline parts might not be rated for much more toque. And once out of first gear, full torque is allowed.
So I guess my question is: do the other transmission makers (Ford, ZF, etc) have similar limitations, where max input torque can exceed max output torque when in first gear?
[Heck--I almost forgot--a torque convertor can get upwards of 2:1 torque multiplication. That's not near max torque of the engine, but it's gotta be a factor too.]