I have a 2000 Diesel Ram 2500, 4"straight exhaust,K&N filter, 85K miles, 5 sp.std. Running a SuperChips box. I have a close friend with an 01' identical otherwise. I get 18+mpg, he gets 22 with no box. What is the diff?

 

What gears do you have in the two trucks?

 

Reply: 3.55 final drive. (both trucks) I drive mine highway at 2000 rpm. (approx. 67 mph) My buddy drives his like he stole it!!!!

 

2000 rpms at 67mph sounds like a 4.10 geared rearend. At 70mph I turn about 1900 rpms with 3.54 gears and a auto tranny.

These trucks start loosing fuel mileage above 1900 rmps.

 

Thanks for the input. I bought the truck used about a year ago (from a dealer) It was advertised as 3.55 gearing. I have no gripe about power, just non-tow economy. The 4.10 issue answers a lot of questions. Is there any code on the veh. to check without jacking it up and counting revolutions of the wheels and drive shaft?

 

It should say on the sticker on the bottom of the hood.

 

Mine has a sticker in the glove box that told me what gears I have and what axles.

 

Glove box as stated. It's pretty easy to see.
The difference would explain the situation very well. Driving a bit slower would help some. (like 60-62 with those gears)

 

how are you computing mileage are you using the display in the truck do you both have the same size tires also,I get on the highway around 17 mpg unloaded loaded its 11 mpg

 

I calculate the mileage my self. (do not have onboard readout) Set trip meter on odometer to 0, fill tank to same level each time. Divide miles traveled by fuel on fillup. I used the friends truck to check on his ranch for him while he was on a cruise for a couple of weeks and I was astounded by the difference between the two seemingly identical trucks, same gearing, transmissions, tire size, fueled at same place and about 10K more miles on his. As noted both are 3.55 diff. (verified) I have the "improvements" on mine and his is "bone stock" Thanks for all the feedback----OGR