Hey Guys,I'm looking for any information (help) on milage.I'm thinking of buying a 2001 Freightliner 12.7 Detroit,10 speed smartshift.373 ratio 22.5 tires.I would like to turn it into a toterhome.I will remove the front axle only run a single.The home will be a 16 footer,will be hauling a trailer 34ft.about 20,000-22,000 so to say the least it will not be working to hard.what kind of MPG can I expect,would I be better off with a 358 ratio or a 307.I plan on criscrossing the county so I'll be on flat and in the mountains.P.S. the Detroit has 430 horeses.Thanks for any help.have a
G:) :) D day. Walter :help:

Most DDIV's get close to 7mpg. at 80,000lbs. You should get high 9's minimum...T

My '98 was getting right at 6.5mpg set at 430 horses running 80,000lb.+ loads with 3.55 gears and tall 24.5 rubber. While having it inframed, I shipped the ECM out and had it reflashed to a low-NOX 500hp setting. Mileage jumped up to about 6.8mpg. With the set-up you are describing (approximately 40,000lb. gross), I'd expect about 7.5mpg. If you have your mind set on this rig, go with lo-pro 22.5 tires, 3.23 gears (or close to it), and have the ECM flashed to 500hp. That should get you up in the 8-8.5mpg range easily.

Thank you guys for your replys,I like T's a little better high 9's touching 10 would be great.I don't know what the ECM is.How is it good to turn up the horse power and not have axle ratio.Does the horespower make up for the high ratio over time as far as better milage goes.This horse power and ratio has always gave me a headach,I'm not dead set a this set up if somebody else has a better idea I'm all ears.
Thanka again Walter :)

You'll be lucky to get 9mpg on an empty rig. You've got a large engine, with a heavy ass drivetrain, and your light weight will be somewhere in the 15,000 pound range. Add a 16 foot home on it, then hook a 22,000 pound trailer to it, and you are definitely looking at 40,000 pounds gross. If you think you can drive a 40,000 pound vehicle in both the mountains and flatland, and average 10+mpg, it ain't gonna happen. The best way to get mileage is to make as much horsepower and torque that you can, and use freeway gears (3.07's for example). But finding drop-ins with that gear ratio will probably be difficult, because most rigs use gears from about 3.23's and up. You could run tall 24.5 rubber to lower your RPMs even more, but then you've got quite a climb into your bunk, the vehicle will have a higher center of gravity, it's more wear and tear on your brakes and clutch, plus you'll be adding several hundred pounds of weight to your rig. Diesel trucks are designed to haul 80,000 pounds consistantly. Mileage is a secondary concern (lucky for the oil companies). If you can't live with the thought of 8 or 9 mpg, I'd consider trying to find a diesel powered bus or motorhome that can tow a 22,000 pound trailer instead of trying to convert a big rig.

"T"- If you own your own rig, and can tell me how to get 9+mpg on a 40,000 pound rig (or in my case an 80,000 pound rig that's loaded half the time), please speak up. I'd love to cut back on my $1000+ per week fuel bill.

Most of my customers are getting 7 and change when driven themselves. 6.4- 6.7 when driver driven. FLD112's do better than 120's also. Don't know what you have. Keep in mind he's building a camper. Self contained and generator driven. Cut the overnight idle out and run on gen. power, remove the power divider and second shaft. Clean injectors and tite overhead, good oil and 1/2 gal. Lucas. Ya, well into the 9's, no prob... The mileage increase comes from the low nox re-flash, not the 500hp bump, and only with an inframe and updated pistons. Timing advance is faster on the low horsers. Mail trucks and lite loaders get better mileage with the low horsers than the 500's. He's lite, sooo... Junk the 10 speed and put in an RTLO14713 without a pump. Trade for tall rubber and see where you land. Eatons and Rockwells go to 2.64 and above, so how fast you wanna go? 3.36 and 3.23's are the cheapest gears to buy, and the most available at salvage yards. A good set of takeouts are $1500 still, and you only need the rear driver... No I don't own one. Just rebuild them, every day. Good luck...T

Thanks Guys,this is what I need is a real life driver and a man that helps drivers(owners) by building this stuff everyday.I'll take high 8's maybe 9's,I would rather ask you guys then some RV owners that will BS you.Thanks a lot for your time.
Walter :)

Most of my customers are getting 7 and change when driven themselves. 6.4- 6.7 when driver driven.

Must be some pretty flat land (or very light loads) out there.

Cut the overnight idle out and run on gen. power, remove the power divider and second shaft. Clean injectors and tite overhead, good oil and 1/2 gal. Lucas ...only with an inframe and updated pistons.... Junk the 10 speed and put in an RTLO14713 without a pump. Trade for tall rubber and see where you land. A good set of takeouts are $1500 still, and you only need the rear driver.

Sounds like quite the list to make 9mpg. Since you build these trucks, how much do you think all this would run? I'm seeing a minimum of $20,000. Also, I'd hate to spend a couple grand going to tall rubber just to "see where I land".

The mileage increase comes from the low nox re-flash, not the 500hp bump, and only with an inframe and updated pistons. Timing advance is faster on the low horsers. Mail trucks and lite loaders get better mileage with the low horsers than the 500's.

I get better mileage climbing a mountain with half throttle to a 500hp engine, than having it floored with a 430hp engine (plus downshifting). Doesn't matter if I'm empty or loaded...

I talked to a guy that converted a Freightliner to pull his race car. He had 430hp Detroit and the forward drive axle was removed. He had allot of problems with U-joints because of the drive shaft angel. He lower the carer bearing to fix it. He was shocked by the fuel mileage. He claimed 10mpg and said the he had a D-Max be for that could only get 9pmg pulling the same trailer.

:exactly: :rolleyes:

If I'm wrong, then I'm wrong. BUT, the facts that I have given are based on MY everyday experiences. I am the one pumping the fuel into my tanks every day. I am the one driving my rig up and down the road every day. And I am the one paying the fuel bill at the end of the month. If anyone has the incentive to get good mileage, it's me. That's why I chose to buy a Detroit over a Caterpillar (although I regret that now because I have to go to Freightliner to get parts for my Peterbilt). My arguement is not based on "You should get...", "My customers say...", or "A guy told me..." Until someone can post up some ACTUAL miles driven/fuel used numbers, I'm still skeptical that you can get a 10+mpg average from a 40,000+ pound rig that runs both mountains and flat ground. And I wouldn't be the person to spend $60,000 building a rig, just to HOPE that it gets good mileage...

Dude, we're all on your side. I truly wish you, and all of us, could get 50mpg with the way fuel prices are now. I've seen 10 single truck owner-operator/ customers of mine sell out this year already, and every half mile on the highways everywhere is an old hopper bottom or bull rack set-up sitting in a farmers yard for sale. Fuel prices suk, period... If you re-read all the posts on this thread, I quoted the truck he's already building. I just suggested the 13 speed to add 'cause he'll hate the 10 (if he's a trucker). I'm sure you can testify to that. He just asked where he'll land mileage wise with the build he's doing. Don't think anyone said 10+, and I know I wouldn't have. Well into the nines is very possible. Been there, dun that. Yours is a work truck. It won't happen for you. You can play turbo/ injector games and maybe even cam timing to get into the 7's, but you have to way the trade off. $2700 in injectors and a $1500 turbo with labor is a big chunk for .2 or .3mpg (or not?). Duz work tho, depending on current build... The info I gave is also based on MY experiences, which is very broad. I'm on my 22nd year doing this, and just finished my #1500 overhaul party this weekend (#500 was big, #1000 was huge, this one was stupid and I'm probably dun now :o: ). I think I still hold all of the records for single turbo over-the-road road torque and mileage numbers that actually live to 700,000 (handfuls of 1000hp's, 2 1200hp drivetrain crushers, piles of old 310B's getting 8+mpg hauling mail, egg cartons, etc...). I'm not gonna lie about ANYTHING, and all my info is always free. I have no secrets, and all my numbers and builds and tricks are there for the taking. Just ask. I'm not really a pick-up guy (tho I've got some cool ones out there). All I do is big truck, 4X4 Steiger type farm stuff, dozers, quarry motors, big piston work motors that most people never heard of. Don't have to bend over as much... BTW, Pete is a TEPS type dealer and can sell Detroit parts for the same as Freightshaker, tho they aren't required to. I know Detroit is trying to lock everyone out after the buy-out wars, but they haven't succeeded yet, and not sure if they ever really will, despite what THEY will tell you. Call or IM me if you have any questions or just want to talk some more. Be cool and good luck with all...T

Dude, we're all on your side. I truly wish you, and all of us, could get 50mpg with the way fuel prices are now. I've seen 10 single truck owner-operator/ customers of mine sell out this year already, and every half mile on the highways everywhere is an old hopper bottom or bull rack set-up sitting in a farmers yard for sale. Fuel prices suk, period... If you re-read all the posts on this thread, I quoted the truck he's already building. I just suggested the 13 speed to add 'cause he'll hate the 10 (if he's a trucker). I'm sure you can testify to that. He just asked where he'll land mileage wise with the build he's doing. Don't think anyone said 10+, and I know I wouldn't have. Well into the nines is very possible. Been there, dun that. Yours is a work truck. It won't happen for you. You can play turbo/ injector games and maybe even cam timing to get into the 7's, but you have to way the trade off. $2700 in injectors and a $1500 turbo with labor is a big chunk for .2 or .3mpg (or not?). Duz work tho, depending on current build... The info I gave is also based on MY experiences, which is very broad. I'm on my 22nd year doing this, and just finished my #1500 overhaul party this weekend (#500 was big, #1000 was huge, this one was stupid and I'm probably dun now :o: ). I think I still hold all of the records for single turbo over-the-road road torque and mileage numbers that actually live to 700,000 (handfuls of 1000hp's, 2 1200hp drivetrain crushers, piles of old 310B's getting 8+mpg hauling mail, egg cartons, etc...). I'm not gonna lie about ANYTHING, and all my info is always free. I have no secrets, and all my numbers and builds and tricks are there for the taking. Just ask. I'm not really a pick-up guy (tho I've got some cool ones out there). All I do is big truck, 4X4 Steiger type farm stuff, dozers, quarry motors, big piston work motors that most people never heard of. Don't have to bend over as much... BTW, Pete is a TEPS type dealer and can sell Detroit parts for the same as Freightshaker, tho they aren't required to. I know Detroit is trying to lock everyone out after the buy-out wars, but they haven't succeeded yet, and not sure if they ever really will, despite what THEY will tell you. Call or IM me if you have any questions or just want to talk some more. Be cool and good luck with all...T

I'm not saying we're taking sides here. I know we are all on one side: trying to keep the screwing from the oil companies to a minimum. And Tierod said he knew a guy that claimed 10mpg+, that's why I called BS on that. As for the 10spd/13 spd deal, I've had both and liked both. Only thing about the 10 spd was that the jump from 9 to 10 seemed like it needed to be closer. And Super 10's just suck cause you're splitting gears all the time. 3 local Pete dealers and a Western Star dealer refuse to touch Detroit stuff cause of all the BS they have to go through to get the parts. When Freightliner bought them out, they recalled all the parts in everyone's inventory. Then they told the retailers they would have to reorder everything they wanted. Pi$$ed them off enough that they decided it wasn't worth the hassle. Congratulations on rebuilt #1500. I used to work on trucks/forklifts/tractors years ago, but then an old timer gave me a priceless piece of advice: It's a whole lot easier to drive 'em than it is to work on 'em!

Detroit tried that here, so everyone put an order in on exactly what they already had and said go for it. Screws turn both ways!! Wish I could drive, but the rumble puts me to sleep. Not too good for that job. Anyway, good luck guys...T

Hey T,are you in the phone book or can you mail me off line.
Thanks Walter wjkola@msn.com :grd:

wjk54 check ur mail