GM/CHEVROLET HORSEPOWER AND TORQUE CURVES
If you study the performance curves below you will see two major benefits of GearSplitting. As an example we’ll use the TH400 or 4L80E trans chart with a Vortec 7.4 (454). Gears are multipliers of torque so at 3,000 rpm in 2nd-over the torque multiplier is 4.73 where without the GEAR VENDORS you would get into 2500rpm in 3rd-direct at 4.10. The difference in engine torque is only 10lbs ft. but the difference in the multiplier 4.73 vs 4.10. That’s over 18% more working torque.
At this same moment horsepower at 3,000rpm is 260 instead of 210 @ 2500 which is over 23% more horsepower with all the reliability of your stock powerplant. To figure the drop in rpm or torque multiplier from on gear to the next calculate as follows: Final Drive Ratio of the gear you are shifting to, divided by the gear you are shifting from, minus 1, times 100. The difference from 1st-over to 2nd is even more dramatic. This is why if you are towing or loaded heavily, the best way to reliably improve performance is with the GEAR VENDORS UNDER/OVERDRIVEâ„¢. It’s the same reason the big 18 wheelers have 2 and 3 speed auxiliaries for 10 to 15 or more gears.
Click on graphs to enlarge.