Hi – I'd like to get some input and opinions on a Cummins N-14.
I have a 2001 Century Single axle with a 370 HP N14, 10 speed (.74 OD), 3.91 rear gear, 22.5 tire. According to my GPS the motor turns 1550 at 60 MPH and 1650 at 65 MPH. I tow a 36 foot gooseneck car trailer. The trailer weighs 12,000 – 14,000 pounds at the very most.
I'd like to be able to roll along at 75 mph at 1400 rpm. I used the Roadranger website and their road speed calculator says to use a 3.08 or 3.25 ratio depending on the tire (498 or 501 revolutions per mile).
I haven't reprogrammed the computer to "owner operator" spec. as I wanted to do that after I changed the gears.
1) Do any of you have any experience with gear ratios and the "pros & cons" of a longer gear verses a shorter gear and how it affected their trucks performance, economy etc.
2) Also what are your thoughts on increasing horsepower output? How does this effect the fuel consumption? There are two schools of thought. The first is – If you increase HP you would increase fuel consumption. The second is- If you increase HP the engine works less and therefore consumes less fuel. Does anybody have any experience with this?
Right now the truck gets right around 8.5 – 9 MPG at 60 mph towing the empty trailer mentioned above (7000 lbs.).
Any input would be appreciated.
Chuck
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