We used to own a 2000 DDEC 12-liter, 430 HP in W900L pulling 53/102 dry box. KW ECM showed high 7's for fuel mileage. The best I ever did was 8.4. Looking at buying 2006 FTL Coronado high-rise condo, 18-spd, 3:58 and L/P lo-pro 22.5 and 53 dry box. Normally like to run 5 MPH below interstate speed limit and all east of Texas. Curious as to REAL fuel mileage expectations, if any of you have good experience with pre-07 DDEC motors. Thanks guys.....
Detroit Diesel, 06 515 HP fuel mileage
The 14 litre doesn't do quite as well.... still, I'd guess that low 7s would not be unreasonable. With an 18 and 3.58s it's pretty well geared to run 65 unless it's a double overdrive, and might actually do worse if you slow down without running in direct.
With all the egr crap compared to that 2000 you will be lucky to get 6.5.............I have an '05 mid-roof columbia with a 10speed and 3:55 gears and run 62-63mph, idle NONE and with the pittsburgh power muffler grossin 76k i can get about 6.6
10 Speeds wont get the mpg of a 13/18 speed. I drove a 10 columbiaa and got terrible mileage. No thankyou. The truck I am looking at now has a 13 and should put me in the mid 7's in a century. I drove Century's for CR England with a 13, had no problem getting 7.6 with a load. Most of them were 500 hp. For that matter here is the specs of what I am looking at.
EngineDET 6014.0 515
Front Axle SetbackYES
Front Axle WR12,000
Rear Axle Ratio3.42
Rear Axle WR40,000 lbs.
Fuel Tanks Count 2
Fuel Capacity 200
Suspension FRGHT Suspension ModelFA240000
5th WheelAIR SLIDE
Front Wheel Type ALUMINUM
Rear Wheel TypeALUMINUM
BBC/Cab LengthRoof Fairing
NO Side FairingPartBody
LengthExterior ColorMED RED
Interior TypeSTANDARDInterior ColorGRAPHITE BLACK
Mileage Adj Price $ 37,250
And as far as those spec's you may wanna do some research as that was a 9sp transmission converted to 13sp and the only benefit to switching it to a 13sp is resale value according to www.roadranger.com/ecm/idcplg?IdcService=GET_FILE&dID=204935 you would be better of having a 10 speed and running it in Direct drive then that 13sp with a final .73 but hey what do I know it's early and I haven't had coffee yet lmao
13 or 10 or 18 or whatever it dont matter im not a trans expert but the gear ratio in the rears is what you need to figure out to match the directdrive gear in the trans. if you want to pull a hill like there is no tomorow then gear low and sacrafice mpg. if you want mpg gear high and sacrafice power in the hills. i have a 16913 with 3.70s behind about 650 hp grossing an average of 126000 to 132000 and average 4.4 empty runing 65 i only get 6.2 at the best. but i set it up to pull a hill.losttrucker Thanks this.
The truck listing showed 3.42 rears. I have that ratio in my truck now and have a love/hate relationship with it. In most cases, it is a fine ratio. But overall, based on my loads and runs, I would be much happier with 3.55 or 3.58. I usually have to split down to 12 with the 3.42 rears to keep from lugging once I run below 60mph. With 3.42, 1400 rpm will put you right on 65 mph, 1300 gives you 60 mph, give or take depending on the tires. 1400 in 12th will give you 55 mph. That is also is with a .73 final ratio in my 13 spd. In 12th, I have .86 ratio, direct in 11th.
Overall, I usually average around 7 mpg year round, a little less in winter, more in summer. Generally running average of 70,000 lb and doing a high percentage of two lane, rolling hill roads.
That '06 is spec'd pretty well for general freight. You should be able to negotiate the price down somewhat. On the surface, seems like a decent working truck. But, like most things nowadays, it needs to be researched out well to reduce the risk of getting a lemon.Last edited: May 13, 2010