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Changing final drive gears have 0, nil, nada, effect on engine power! There is no change to the engine power curve. When done properly, dynomometer testing accounts for this variable.
What you will gain is more rapid acceleration with the same engine power since your torque multiplier is higher.
I still think there would be some small loss of power with lower gears. I believe this is always the case when increasing mechanical advantage. I don't think it would be a significant loss, about like the difference between a dyno run in 3rd gear versus 4th.
This is a dyno done for something else but I had the 4.44 gears up and running at the time.
See for yourself.
- 4IG CAI, 4.44 gears otherwise stock.
- 4th gear pull
- Ambient temperature with industrial fan blowing into the front scoop.
- 9000 miles + on my car.
While there are small differences in losses for different ratios, they are _small_. And when you consider that there are a number of gears and lots of other sources of driveline loss, it becomes almost unnoticeable. The difference in loss between a 3:1 gear and a 1.5:1 gear is _theoretically_ less than 1%. Taken in the context of overall driveline loss, this would be very small indeed (less than 1 hp). The difference between a 4.10 and 4.44 rear gear should be even less.
If you could do runs in 2nd, 3rd and 4th and hold load time constant (not an option on inertia dynos such as the dynojet), you'd find that power varied less than 1%. If any changes did show up from a rear gear swap, I'd expect them to be due to a change in gear design, or changes in installation/clearances.
09-08-2003, 04:01 AM
