Engine/Transmission (1998.5 - 2002) Power to wheels

[ESwartzer]

I have a 98. 5 cummins whith several power upgrades that I assume would put me in the 280 - 300hp bracket to the wheels. I am currently using 3. 55 gearing , and am considering a change to 3. 73 gears. Can anyone tell me how to figure the HP change to the wheels with the 3. 73s. vs 3. 55s , or if there even is one. I know that pulling my 5er would be easier with the lower gears,so i would think there would be a HP increase. Could someone fill me in please! Thanks ES













1998. 5 ext 3/4 4x4 full pillar isspro gauges+fuel 4in. exhaust K&N full ddt trans, 89% converter, 275 bosch injectors,Van AAken. 265/ 75/16 michelins, dello 400 in the engine, amsoil everywhere else

 

[WestTN]

3.73's

I'm not sure if you can get 3. 73's for your axle. The other ratio offered by the factory was 4. 10.

Also, most experts in RVing and racing say you should not bother with only one ratio step, as it will never be cost effective. It takes more change than that to be noticable. Of course if you need repairs anyway, then the cost would not be any different. The change you are contemplating is only 5% difference. 4. 10's would be about 9%. You will also introduce speedometer error.

 

[JFinke]

You will change the HP at the same speed as the power curve will change by the 5% gear ratio differance. As far as max HP it will be very close but the closer to a 1:1 ratio that you run the closer to 100% percent efficiency you will achive in the rear end. The higher the ratio (numerically) the lower the efficiency. Jake