Diesel motor/AT trans choices

[Indianracing]

Hi all,
I`m interested in getting a MDT as a conversion with a garage. I`m just researching diesel motors for MDT applications. I prefer something made from 1993-2003, before more stringent emissions. I`m also looking for something already built with a toilet and shower that I can upgrade.
I like the International and Freightliner trucks. The DT466E series seems to be the best motor for longevity and service. Most Freightliners have the Cat 3116, 3126 series which seem underpowered unless tweaked to the breaking point. The Cummins N14 seems like the better choice, but I`ve rarely seen one in a MDT. Can a Freightliner FL series, up to 2002 or 03, be retro fitted with this motor and if so, costs? Also, what is the best AT for any of these trucks in an Allison? Thank you all in advance! Art

 

[Dogtales]

You may want to give this a try if you haven't already:

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[Indianracing]

Thanks Dogtales,
I`ve used racing junk for years. I`ve also found the site "escapees" which has tons of good info.
This is going to be a slow process to zero in on the right unit. I would like to retire to the road for about 5 years full time. Stuck between an MDT and HDT in an all in one unit. Fuel mileage is the biggest concern and overall reliability.

 

[Bob86ZZ4]

From the very little bit I know about MDT's I'd suggest you forget about them. Go look for a HDT. I don't think your mileage is going to be any worse. The availability and cost will be better for an HDT I think. My son bought a '03 Freightliner FLD120 Classic, with the Cummins N14 engine, big huge condo sleeper with upper bunk, for $18k. It's got a straight 10 transmission which I know you aren't wanting. But, he's been using it for almost 2 years with almost no problems. It's a working truck so he's running 80k lbs. most of the time. Those N14's were great motors.

 

[Indianracing]

Thanks Bob86ZZ4,
After researching the last 5-6 weeks, I`m coming to the same conclusion about HDT`s vs. MDT`s.
On the bottom of your email and your avitar, is that your rig? What are you getting in overall mileage with your setup with the 3.42 rear and the Eaton 10 speed, an Autoshift?

 

[Bob86ZZ4]

Yes, that's my rig (well actually it's the banks but in about 20 years it will probably be paid off). I scale at about 29k lbs. with full water and fuel. I pull a 24' enclosed car trailer with car and lots of tool and spare parts. Guessing the trailer weighs about 8k when full. It's a fully aluminum frame trailer so empty it's only 3k. I pull the trailer about half the time. I cruise at 70-72 mph most of the time. I'm seeing about 1500 rpm's at that speed. I'm very very anal about my fuel mileage record keeping. I have put 40k miles on in the 5 summers I've owned my rig. (I live in MN so it's tucked away for half the year). Lowest mpg is 8. Most often I'm in the mid 9's mpg. Often closer to 10 w/o the trailer. I usually cover about 700 miles a fuelling. So that means there are lots of stops and starts and city driving mixed in with the highway miles. Once I topped up and got directly onto the highway and drove about 200 miles and got off and topped up. Got 12.x mpg (can't remember exactly but mid 12's I think, my log book is in the rig which is 30 miles away from me right now so if I remember next time I go to it I'll refresh my memory). I have 92k miles on it now. I've been told these big engines get better mileage when they get up to 100k miles. I do think I've been getting better avg. mpg lately than when I first bought it with 50k miles on the clock. I've got a 3 pedal autoshift.

 

[bushpilot-TC]

i have simular experience to bobs.
I just rolled 105k miles - and we're averaging about 15-18k a year

were get a very consistent 9.9 mpg (cruise set at 72mph).
the worst I've ever seen is 8.6 (hauling ass thru the mountains of tennessee to the northern tip of virginia).

our recent best was this past august - blacksburg va to ft walton beach at 12.8 mpg

the 12.8 included a few hours of generator run time - (sleeping in rest area w/ air conditioning) and we were pulling the jeep. That particular leg of our trip our speeds were slow (50's & 60s) for about have the drive (south of atlanta).

Our coach is a Freightliner Columbia (42ft, all house, no garage) w/ an MBE 4000 (12.8L, 450hp) & the 12spd Meritor/ZF Smart-Shift

Lightly loaded I top the scales around 26k thats w/ 1/2 tanks of water (120 gal) and 1/2 tanks of fuel….i need to reweigh w/ full tanks, clothes/food & the jeep (just for fun).

 

[Indianracing]

Thanks Bob and Don for your input.
What do you think the difference would be if your rigs were twin screws? I was looking at a 2000 Freightliner that had the 435hp Detroit with 10 speed Autoshift and he was averaging about 8 mpg, which seemed a little low to me. The unit has a garage and weighs in about 30k, and that was bobtailing it with no trailer.
I`m sold on the Detroit 60 series and the Eaton 10 speed Autoshift. I`m thinking if it`s twin screw you need at least 500hp or the 14.0 liter 515, which is another good proven motor. A bigger motor should breathe better and get better mpg since your not having to push it as hard to roll out with a 28-30k rig.
I ask an lot of questions because I want to make the right decision when I buy. I will probably have to finance, but that`s o.k. too, since it will allow me to buy something better that will last the next 20 years..... Art

 

[bushpilot-TC]

I wanted and was looking at twin screws, i liked the idea of having an added margin of safety in extra tires & traction…..then i started pricing tires (3k dollars per axle)….while nice to have…i simply didn't need the extra weight carrying capacity.

NOw….unless you're towing a stacker or a huge trailer i can't imagine needing the 2nd screw.

if i had more HP, id use it…and i surely wouldn't be getting better mpg.

I've got twin 60 gal tanks and would wish i had larger ones - just for the range, although the longer we own the coach we end up stopping every 300-500 miles just so the dog & i can take a break.

 

[Indianracing]

Hi all,
I`m interested in getting a MDT as a conversion with a garage. I`m just researching diesel motors for MDT applications. I prefer something made from 1993-2003, before more stringent emissions. I`m also looking for something already built with a toilet and shower that I can upgrade.
I like the International and Freightliner trucks. The DT466E series seems to be the best motor for longevity and service. Most Freightliners have the Cat 3116, 3126 series which seem underpowered unless tweaked to the breaking point. The Cummins N14 seems like the better choice, but I`ve rarely seen one in a MDT. Can a Freightliner FL series, up to 2002 or 03, be retro fitted with this motor and if so, costs? Also, what is the best AT for any of these trucks in an Allison? Thank you all in advance! Art

Getting back to my original question, above, has anyone changed out a cat 3116 or 3126 to a bigger motor (HP and torque) in a Freightliner FL series MDT?

 

[Iron Pony]

Yes I have swapped out the little Cat 3126 for a ISC cummins. But I'm a highly experianced heavy equipment mechanic. If You do it you will have to have the engine wiring harness and ECM from the donar. And be able to get the complete wiring diagram for the truck. The engine wiring diagram is real easy to get. Trucks not so much. The good news is the Cummins ISC 8.3L was used in some freightliner FL70 trucks so finding a adaptor harness to go from the Cummins engine to the Freightliner chassis should be able to located. And that would make the job way easier