Tacsavage

There was a recent article in one the diesel mags, I will have to look for it. Where they were trying to up the fuel mileage on a 6.0 ford. They got it up to about 23 mpg by doing intake, exhaust, tires, and chip. They decided to try and do even better, so added a gear vendor. They actually lost mileage because the gearing dropped the rpms below the optimum range for that engine. They figured that it would increase mileage if they were able to run 85 mph. So I guess you have to look and the various factors. I would look at what rpms you run, where you live (flat land or mountains), whether or not you tow, your tire size, gear ratio, trans, etc. A lot of factors to look at. Tough decision for sure. Tac

dslpwr81

Hey guys. I have a few buddies here in town that have gear v. in thier trucks, and they all have told me that they didn't really notice any increase. One says he can see around 1 or 1.5 difference, but once again.... there are so many factors out thier. Oh, and I think that HOV hit it right on the HEAD!!!!!!!!!!!!!!!!!! I feel I can't say that loud enough. lol I agree that wind is the killer in MPG. Not so much RPM. Think about how much better mileage you get with a sweet tail wind doing 80mph? Even higher RPM, but better mileage than if you were at 60mph in normal conditions.

Nsomniac05

Hey Nelrod, where you talkin about the foothills of NC on I-40? im orriginally from Yadkin County. I went to Forbush High school. you trackin?

nelrod

Hey there insomniac - - I am in Burke county, near Hickory and Morganton. I am from Alabama, but went to school at Carolinas Medical Center, and ended up here working in Hickory. Been here in NC total of 22 years. I obviously like it. I have roamed around in Yadkin County on my motorcycle before, beautiful place.

gorms

I'm confused... why don't the new common rails get better mileage??? I've been considering trading up for either a 2nd gen 24V or an 04-06 common rail. I'm not very interested in the new 6.7's reading about all the emission issues and fuel mileage. It may be corrected in a few years, but... seems like there must be an easier way to make it all work simply.

Disregarding emissions, my ancient 12V consistently gets 17-19 around town going easy (never less than 16), and 19-23 highway; empty of course. With my 1971 11' in-bed camper, 12' trailer with two dirtbikes and all of our gear/firewood/gas etc. weighing in total of over 7k lbs cargo I get 18 on the highway going 70 mph. I have seen too many 24V's reporting under 17mpg empty!. Why can't dodge/cummins get the numbers up? My fiance's Jetta TDI gets almost 60mph highway, and no less than 43 in town.

PS wind has an astronomical effect on MPG. I know this from windmill calculations- doubling wind speed offers 8 times the power available I think...or is it 4 times the power? Either way, its exponential, so the faster you go the drag increases more and more.

nelrod

Can't have 325 hp and 610 ft lbs of torque and still get the kind of mileage your 98 12 Valve gets. How much HP and torque is yours rated. The HP wars year after year is where we ended up. (I, and most people love it though) I bet they could detune to whatever hp and torque you have and get pretty close. However, we have the dreaded 3rd injection event, which, I understand it sprays fuel for sole purpose of keeping the catalytic conveter hot. I would love to have a good ol electronic free 12 Valve like yours, way more dependable, way better mileage. Anyhoo, that's what little bit I think I understand.

stickler

Agreed. Our speed limit here is 100 km/h or 62 mph. I get very near 20 mpg US at that speed, and closer to 23 at 55. The wind drag makes a huge difference. Ever check mileage when running into a strong head wind or even worse, a head/side wind? Yup, it plummets like crazy.

Best I ever got was one time running in an ice storm. It was so slippery I never got over 35 mph for over 200 miles. Well over 35 mpg US had calculated. But who else would ever run that slow? LOL!

I've often meant to do a test in direct at speed limit, to see if maybe I'd do better at higher RPM. I'm only running 1750 at 62.

moorepower

3rd gen are much heavier! Weight, Power, Lead feet

kuhkuhkyle

I ran 864 miles to north eastern Colorado from North eastern nevada. I filled up in Rawlins Wyoming. Its 519 miles roughly and had a little under a 1/4 tank. That was doing 75 mph, and with the Smarty loaded on SW9 4.11 wild. Forgot to change it before i had to leave for there. The tires have helped a ton for mileage. Calculated it was 19.7 mpg. IMO thats very good for the weight and size of the truck. I'm happy with it. Fuel prices are a killer but if i wanna drive my truck, i have to pay them.

HIGHGEAR

Drove 688.5 miles on one tank of fuel. Granted, I was driving conservative and never went over 65mph. The majority was about 90% highway running, set cruise at 65 mph, the other 10% was city running. I had the SMARTY set at SW#3, TM#2, TIMING#4, RP#2 and WASTEGATE#1. For my truck this is great. Hand calculated it, I was getting 19.6 mpg. (trip meter said 23.6)

cquestad

Not worth it...drag increases with velocity at and exponential rate...

It will help...but not much.