Quote:
Originally Posted by Michael_S
But you have to look at the gears inside the transmission.
If I remember right, the 4 speed automatic had 3.04 first, 1.57 second, 1.00 third, and 0.68 fourth gear.
The 6L80E first four gears are: 4.03, 2.36, 1.53, and 1.15.
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4L60/65/70-E: 3.06:1, 1.63:1, 1.00:1, 0.70:1
4L80/85-E: 2.48:1, 1.48:1, 1.00:1, 0.75:1
6L80/90-E: 4.03:1, 2.36:1, 1.53:1, 1.15:1, 0.85:1, 0.67:1.
The 4L80/85-E takes less power to turn and is thus more efficient, however with more gears and a better spacing the recovery RPM helps keep the engine in the fat part of the torque curve.
The 6-speeds do a better job with less rear gear, but with 3.42:1 final gears that 6th gear is essentially useless on all but the flatest ground.