Schoolbus DT360 engine swap in truck-horrors!

Discussion in 'Diesel Tech' started by mccormick, Mar 28, 2011.


  1. mccormick

    mccormick Farmall Cub

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    OK, I thought I was being pretty smart, I found a local Low milage school bus with a DT360, 540Allison well maintained and CLEAN CLEAN CLEAN! Price was right and I was going to put an old farmturck cab and sleeper on the bus chasis to make a toy hauler for antique shows and the like. Everything was cool and I was thinking how this was going to be so much better than the guys doing it with a Cummins on a 1ton Dodge Chassis when I Discovered the school bus was only getting 4-5 MPG! Goodness, this aint good! Of course the truck body will not push the air the 93 school bus did but it can't be a lot better with a trailer. THe gov is set a 2700 pushing around 60mph all out. I realise I could get an Allison with an overdrive but that is a lot of money. Is there anything I can do as far as an overdrive or a two speed rear end with a high ratio? Any suggestions would be appreciated, its got spokes with 9.00x20s so I might put bigger rubber on it if it would help? Thanks for your advice, Aaron
     
  2. John Donnelly

    John Donnelly Administrator Staff Member Administrator Moderator

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    4-6 MPG is pretty good for what it is.

    With what you plan to do it will probably get 10 MPG.

    If you need to lower at speed RPM, put an over drive on it or get taller rear axle gears. A two-speed rear end isn't gonna do it for you with what you plan to do. Two-speeds are for gear splitting so you can drag uber-heavy loads over mountains.

    I would overdrive it.

    -John
     
  3. vegestar

    vegestar Binder Driver

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    Here in my area I have a bunch of hippie guys that thought it would be cool to buy an old school bus, run it on wvo and drive it across the country. Their plans all changed once they realized the horrible mileage and the fact that they can only drive 55. School buses were never really intended to travel at sustained highway speeds and are geared more toward safety (meaning they are heavy as hell).

    The two I service regularly are both dogs, 1 is B-series Ford shortbus with a 6BT, the other is an International with a DT408. What's that? Never heard of a DT408? That's cause they only made it one year, it was a mistake. Also a mistake was the joke of a radiator they put in the thing, it overheats at the faintest sight of a hill. I'm going to be replacing the cooling system for him next week so he can drive back east. He wanted me to install a wvo conversion but I told him money would be better spent getting the rig in better running condition and buying diesel.

    Anyway, back on topic. I'm sorry you found out the hard way that school buses don't make a good platform for custom towing vehicles. Any changes you could make wouldn't net that much of an improvement. My advice is to find some hippie guy to buy the bus for twice what you paid and invest that money in a better truck. You could probably do some goofy camper conversion and quadruple your money, just my .02.5. Good luck!
     
  4. mccormick

    mccormick Farmall Cub

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    Well, the school bus is mounted on a truck chassis, other than the Allison being an oddball if you take the weight of the body off it should preform as good as a truck. I pull my 5th wheel sometimes with my 78 Brigidere with a 6V92 and even it will do better than the schoolbus but the frame is not long enough for a sleeper. Just what is available as far as changing rear end ratios or overdirves? I know when I was a kid there was lots of Semis around with two transmissions, could a guy mount a standard transmission backwards behind the Allison? I could make it all work with the price of fuel today but if it goes sky high I am going to have a lot of time and money in a vehicle I can not afford to use so I am doing my research now. Thanks guys!
     
  5. Cory Smith

    Cory Smith Farmall Cub

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    Allison transmissions are really good at killing power and mileage. If you are after mileage a 5 or 7 speed from a medium duty truck and higher rear end gears will help alot.
     
  6. bmacguyver

    bmacguyver High Wheeler

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    i know on my 1754 with a fairly hot dt466 and a 5.81/8.11 rear when swapped out the allison at545 for a spicer 5 speed i went from 7 mpg 8.5-9 mpg. pulling my 38 foot camper i only drops to 7.5 mpg. top speed is 68-72 mph depending on wind and hill. but full load speed is closer to 50-55 mph, the slowest ive had it pull down to on a hill was 63 mph and was only at 15 lbs of boost highest boost ive seen on it being 34 lbs BRIEFLY under acceleration in high gear. with an auto trans a 2 speed rear isnt used to split gears, but instead is used as a range extender.

    hth

    mac
     
  7. CareyWeber

    CareyWeber Diesel Herder / Moderator Staff Member Moderator

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    The cheapest way to lower the RPMs is to put bigger tires on it. The best way would be to get one of the newer 7 speeds manual transmissions.

    With a manual transmission and lower RPMs 8 - 9 with 10 being max is a real possiblity.
     
  8. Roger McGregor

    Roger McGregor Farmall Cub

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    I'm feel your pain, I picked up an BlueBird FE with 5.9 Cummins cheap,
    only to find out about the dreaded AT545 Allison, If you check around
    on the school boards everyone hates this transmission. The AT545 has
    a non-locking torque convertor, which means you run the engine
    up to full governor rpm and hope something happens. Also note that the
    545 needs 2400 rpm to be at full operating pressure. My engine is governed
    at 2600 rpm. So the accelerator is just an on off switch. My gears are good
    enough to 70 at 2600 rpm, but I'm lucky to make 60 mph on the flats because of the slip.
    Going manual would be the best but it's a lot of work.
    The most reasonable swap is the MT643, it locks in 3nd and 4th, are pretty
    cheap to come by and are not electronic controlled. However you will need
    everything from the crankshaft back.

    As far as Towing goes are you planning on putting a Commercial license
    on the truck. I always wanted to run a Crew cab Dt446 until I found out
    what the license would cost and the fact that I would have to scale.

    That's why I'm going the Bus/RV route, In Iowa just need like 4 things, toliet,
    cooking,HVAC,and cooler to make it an RV. At which point I can pull what I
    want as, as long as it doesn't in involve making money.

    I figure I'm saving money on the cost of truck and license, not on the fuel.
     
  9. IH64Scout

    IH64Scout Dreams of Cub Cadets

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    I finally understand why buses sound like they're working hard and not moving at all....

    -Jon
     
  10. fredsterra

    fredsterra Y-Block King

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    The Dt360 is a great city delivery truck engine. Miles ahead of the DV-550 it replqced.

    But it is by NO means a Dt466! You can do a few things to help a bit. But I don't think you will ever be happy with it.

    That's one reason so many tractor pullers and racers run old tractor trailers now. You can get a lot of power cheap. Plus if you don't need the tandem. Make it a single axle and save of fuel, tires and road taxes. (Check Your Local Laws on that to be sure!)

    Most trucks you can simply remove the front drive axle and extend the driveshaft.

    A Freightliner FLD112/120 Or Navistar 9200/9400 with an M11 Cummis or 11.1L Detroit are cheap! Everyone wants a N-14 Cummins, C-15 Cat or 12.7 Detroit.

    One of my employees just sold his 9700 COE 11.7 Det. that he ran every day and great Virgin rubber for about $7,000 to an exporter that shipped it to South Africa. And I thnk the guy got a great buy. But a typical cab over will run about $4500.00 around here.
     
  11. Dave Nuenke

    Dave Nuenke High Wheeler

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    DT 408????? Are you sure you aren't thinking of a DT404? The 404 was relatively common on the ag and construction side, we have one at work in the big Payloader, and it's an excellent motor. I've never heard of them beign used on the truck side of things, but there is no reason one wouldn't work, as it would bolt right up, though one might want to recal the pump to optimize for road use. When it comes to manual vs. auto, I think that an auto saps the power out of all the DT's, it's just less noticable in a 466 because there is more power there to start with..... I wholeheartedly second the comments about just finding an older semi truck. They are cheap, have the power, have the brakes, and you won't be working one at all. In South Dakota you can farm plate one for about $200 a year @ 26 ton, and you are good as long as you don't haul commercial. For what you are looking at you wouldn't have to plate that high, I do because I use mine as a semi, and should probably plate it higher, but haven't gone through the paperwork to do so yet. (One of those things that doesn't cost much, but is a pain in the butt, they pretty much want to make sure that it's legit private use).

    Dave
     
  12. mccormick

    mccormick Farmall Cub

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    I suppose the smartest thing for me to do is go ahead with the project as is and hope that once the bus body is gone the weight ratio will help the fuel economy. If not then either a different transmission or scrounge up an overdrive plus bigger tires. Since I am only going to use it a few times a year it would take a lot of diesel to equal many new parts. I already own a semi but if your wanting a non comercial truck for antique and horse shows you have some issues with using it for personal events. Plus the state told me on a private vehicle that is never used for farm-hire it can be treated like a pickup in all respects but if I ever get caught using it for work then drivers would have to have CDL, Logs, scale issues and the whole works not to mention paperwork on the truck. I have been using an older Chevy 1 ton with a 427 to pull my trailers and it only gets about 5-7 MPG but I want a sleeper so I can stay with my stuff and the tonner just don't have the weight I would like with a heavy trailer. Thanks for all the suggestions, I wish I lived in an area to find all the cheap parts but things are pretty hard to find around here. Thanks again.
     
  13. stu simpson

    stu simpson High Wheeler

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    Both DTA360s I ran in my trucks got excellent mileage and reasonable performance. The lo-pro box truck with an AT542 got 10 empty and 9 with about 3K# of stone and tools in it. The rollback with a 5+2 got 12 to 13.5, and thats with a 22' steel body and a knuckleboom (and a load of 2 Scout 800s). I wanted to put in a 6+1, but my mileage was already great, and the transmission is expensive. Both trucks had a higher RPM range than the 466s, liked to run warmer than its larger brethren, mech. injection and electronic alike. BTW the DTA360s were mechanical injection only....I wonder how the mileage would have been if they had ever converted to a fully electronic system ala the DT466Es??? I think it is a fantastic powerplant and easy to work on.
     
  14. vegestar

    vegestar Binder Driver

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    Umm, I'm not an idiot. It says DT408 right on the sticker on the valve cover. Like I said, they only made them for one year and that is why YOU haven't heard of it. It'll be here Sunday, I'll take some pictures for you.


    I'm sure these engines a capable of proving themselves worthy, as long as the running gear behind them is adequate as well. It is the same size as a 6BT and we all know what those little puppies can do. I think the major issue (besides weight) is the Allison, but there is not much to do about that without deep pockets. So you are probably well served with forging ahead with your plan. Like you said, you plan on using it only a few times a year, spending large coin would be a foolish thing to do.
     
  15. Roger McGregor

    Roger McGregor Farmall Cub

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  16. Dave Nuenke

    Dave Nuenke High Wheeler

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    I wasn't trying to imply that anyone was an idiot, more along the lines of honest mistake. I'm really the one who screwed up as the 404 is not a DT motor at all, it's the motor in my 856, the motor I was actually thinking of is actually a DT414. What year is this DT408? Now you have me curious if it's a slight variant of the 414 (or they just fudged the cubes to make a "different" OTR motor), or something different entirely.

    Dave
     
  17. vegestar

    vegestar Binder Driver

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    From what I've gathered that DT408 was made in late model year 1994. The bus I am working on is actually titled as a '96 but that doesn't say much. In all my searches for parts all the catalogs have it listed as '94. Sorry, I wasn't implying you referred to me as dumb, more likely my sarcasm didn't come out quite right, lol.
     
  18. vegestar

    vegestar Binder Driver

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    DT 408 pics as promised, check out the goofy radiator/ intercooler setup. Yay, my Scout made it in the picture!
     

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  19. CareyWeber

    CareyWeber Diesel Herder / Moderator Staff Member Moderator

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    Can you get more pics of the radiator/ intercooler setup?
     
  20. vegestar

    vegestar Binder Driver

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    Yes sir, right away! lol
     

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