Will a Diff gear change increase HP

[GreenGremlin]

think of the diff ratio like leverage (tall ratio is like trying to do a bolt up tight with a short spanner, however with a short ratio its like trying to do up that bolt with a bigger spanner).
a 3.08 is relatively tall, takes a while for the car to get going, but a 4.11 will give you more mechanical advantage if your motor can rev hard enough and make torque and HP hig enough up the rev range to use it.
pure physics.

 

[greenfoam]

Changing the diff will help you get more torque and power onto the road more quickly, that's why you go faster but once you are out of first gear and up in the peak torque-power range there's not much difference, then again it takes along to time for the other guy with a bit more peak power but stock gearing to gain back that .3 of a second you pulled in front in 1st gear so it's a good thing.

Also power is calcualted from torque and time (revs)

Read this and you will know all about it

http://www.epi-eng.com/BAS-PwrTrq.htm

 

[Patrio7]

this is probably wrong but heck

torque is, as mentioned the twisting forge of the engine, where as power is the engines ability to keep accelerating under load?