I want to know whats the highest consistent numbers you guys get with your 1st gens high 20's? maybe even low 30's? I am interested because I have a long commute and I have to travel rough roads and its wearing my commuter car out so I am considering using my truck as my daily commuter I don't want to but I may have to so your MPG numbers would be apprciated thanks!

 

I can get into the low 23's. I average in the 19's. Some tanks I get 14. It all has to do with the way you drive. A valet switch is a big help also, and afc tuning.

 

Around 20-23 Driven right. Especially with a 2WD D-250 with stock tires and a 5sp. I have seen 27 with a D-250 auto senior driven! (my Dad)

 

It's a 97 but the ideas are the same http://www.dieselpowermag.com/tech/g...s/viewall.html

Lift will cost about 1 mpg for each 2", brush guards and winch bumpers will cost 1 mpg, expect 1 - 2 mpg less in winter. Fuel: summer fuel gets 3% better mileage than winter. Winter air can drop mileage by 8-15%. Warming up the truck in the mornings 1/2 a gallon an hour at 650 rpm, do that for 10-15 minutes, 5 days a week.... B20 can lower your mileage by 1%.

Keep you in the Cummins "Sweet Spot" 1300-1500 RPM Cummins Turbo Diesel News and http://cumminsengines.com/assets/pdf...whitepaper.pdf

Bigger/wider tires will kill mileage, taller and skinny are better. Watch your PSI.

 

I consistently get 24 on the highway when I go to east Texas. It's about 140 miles one way at 70 mph. That was with the 33s. Haven't checked the 37s but they definitely dropped my rpms. Added a Denny T at the same time so I'm sure it really dropped.

 

Hey Mike, ... how do you define "sweet spot"? The whitepaper link didn't work for me so I need to ask. I pull my 25' 5th wheel camper all summer, and if I get below about 1700 rpm I've got no power, just noise and smoke. My fondest wish for my truck is to get more gears to I could keep the motor in the 1800-2200 range. Meanwhile with my OEM 5spd I get about 23 mpg(Imp) empty and 15 pulling. I'm sure I'd do better with more gears since now I need to roar 2nd and 3rd gears over 2500 rpm to catch the next gear above 1500 rpm. (I obviously don't speed-shift, au contraire I double-declutch on every shift up or down).

 

You'll need to keep in mind that your gallons are bigger then the American drivers on here. To convert US figures to Imperial gallons multiply by 1.2

 

TRY this http://cumminsengines.com/every/customer/secrets.page?

 

With the completly stock non tweeked engine exept for some cheap 30-40hp injectors I usually got 18-22mpg (u.s. gal). The mpg's have went far south since then though..

 

I think the jury is still out on B20. Pulltilbroke got one of his best MPG with IL B20... I think I remember him telling me that he would have filled up in IA with straight diesel or B5. That same trip I got 23 mpg. Low 20s seems to be my average during summer.

Posted via Velocity LG ALLY

 

Okay so roughly 20-25 depending on tires time of year heavy foot and tranny and gearing and anything that drags and 25 with a trailer thats pretty good!

 

I get 25-ish mpg at 65mph, with 3.07 gears, OD, and lots of timing.

 

Valet switch? and afc tuning?

 

I have the same gears od and no timing haha

 

I could find no information about B series or ISB series engines. All rpm recommendations were for ISM and ISX engines that have much lower redlines than our higher revving B series. Usually, those engines are all done at 2100-2300rpm or less.

And as much as I like the mpg study dieselpowermag did on that truck, I don't take it as a realistic test at all. It was never stated how many miles this test was done at. A 150-200 mile test is not realistic at all. It was not stated how the truck was filled either (until the pump clicks, or until fluid is to the edge of the filler neck?). This was not written like a true, scientific study to eliminate these questions of variables. I've seen other fuel economy "study's" at DPM that was documented VERY well. I can not remember the writer, or the truck used, but it was well documented. They mentioned traffic, average speed, weather, and they did all tests over at LEAST 1 FULL tank of fuel if not more.

Perhaps this test was done for a full tank of fuel (which would be almost 900 miles) and it would be a plausible study. But to leave out the information when it's clear that the magazine recognizes these variables in another article leads me to believe this was a short run test for an hour or two.