Originally posted by lazs2
funked has it... torque is needed to pull tall gears. torque is what you feel when acceleratning. All gearing is a "torque multiplie" the less torque you have the more of a multiplier you need.... lower gears and lower top speed. if you have little torque and tall gears, you will not be able to "pull' the gears... say a 2.75 rear end gear with a 150lbs of torque... at 7,000 rpm and say... 200 hp.... the 150 ft/lb of torque car should go about 190mph say but.... the car won't be able to get to those 7000 RPM in top gear because without enough torque the engine won't have enough grunt to punch that kind of hole in the air. The motor simply would not rev past say 4000 rpm.
aerodynamics play a huge role also. In the old days you would just let huge torque numbers poke the holes in the air at speed. That still works and works even better now with modern overdrive transmissions.
lazs
Lazs, actually gearing and ratios are a divizer not a multiplier of net power.
A 5-speed will give you the same top speed as a 7-speed though in an application where the automobile lacks torque throughout its power band or is very peaky, the 7-speed will get you to top speed faster.
(disregarding air resistance & assuming theres enough usable torque for the 5-speed)
ragards,
coffee