Build your own diesel RV

Discussion in 'Shiny Things' started by Joz, Apr 27, 2011.

  1. Nailhead

    Nailhead Free at last!

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    8000 ft/lbs? :eek1

    Now THAT'S good metallurgy!
    #61
  2. Joz

    Joz What could go wrong?

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    It was difficult to measure the 460 while in the chassis and I did it a while ago, but I think the Cummins was only 2 inches longer & about the same width (with the turbo & accessories). I don't know about the bellhousing and the Allison clearing the existing floor pan cut out nor the dog house. I'm fully prepared to modify those. I fully believe it all will clear the firewall without issue. Only time will tell.

    From what I've read, I will need to modify the dog house to make more room for the engine. No problem.
    #62
  3. Streamin' E

    Streamin' E Half-assed adventurer

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    I'm in.
    #63
  4. Carlo Muro

    Carlo Muro Supercàzzola

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    even a small engine with a granny low and double x-fer cases could make 8000 at the pinion. If you have a 100:1 crawl ratio and 5.13 gears it takes less than 400 lb ft at the engine to get to 8000 lb ft at the drive shaft yoke. At that point, the axles themselves would be twisted to the tune of 40,000 lb ft...mind you that you might have to mark the tire with chalk to prove to yourself that it's turning:lol3
    #64
  5. VxZeroKnots

    VxZeroKnots Long timer

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    depending on tire size 3.54 seems alright, i wouldn't go any higher than 3.73 to keep the revs down, but I'm unfamiliar with the ratios in the allison. can we get a model number off the tranny and your tire size? We can figure out what RPMs you will be seeing at the engine using one of the many online gear calcs.
    #65
  6. Zecatfish

    Zecatfish XTique Rider

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    You can solve the diesel generator issue.
    Find an engine from an old Thermoking, they used Isuzu 25HP engines, or an old Carrier, they used Kubotas, from a reefer trailer and add a generator head to it.

    With new smog laws out in California etc the old units are nearly worthless today and the engines run forever. My thermoking has 34,000 hours on it, just started to use a little oil. The Carrier I have has 31,000 hours on it and uses no oil.

    They're heavy for a genset use, but I doubt you could find anything more reliable.
    #66
  7. Joz

    Joz What could go wrong?

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    @ZeroKnots: The Allison is a 542. The tire diameter is 30". I remember seeing a calculator somewhere that you put in the high gear ratio, diff ratio and tire diameter and it would tell you what engine RPM at what speed. Too tired to do it tonight but if you're bored I'd sure appreciate an estimate. Thanks!

    @CatFish: Hmmmm.... that's a good idea but probably out of scope for the next few months. It was previously suggested that an unleaded genset converted to propane would drink fuel. While I don't use it too much I really don't want to fill the propane as often as diesel. I'll keep my eyes open and if I stumble across a small diesel like you suggest I'll snag it just in case!
    #67
  8. Range Motorsport

    Range Motorsport Junk collector

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    at 65mph you will be turning 2584rpm in 4th gear at a 1:1 ratio. Otherwise known as redline for that motor and pretty common on most diesel buses, coaches, and general fleet vehicles.

    Here are your transmission ratios 3.454/2.253/1.407/1.000 and reverse 5.02

    A secondary OD unit would be sweet in this rig to bring the RPMs down to a more fuel manageable 1800-2200rpm.
    #68
  9. Nailhead

    Nailhead Free at last!

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    I'm having difficulty getting behind that one: we're turning an 8.5" bit at the end of 7800' of pipe and torquing up to 8500+- ft lbs. downhole-- I have trouble believing that a driveline could endure anywhere near 8K.
    #69
  10. VxZeroKnots

    VxZeroKnots Long timer

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    turning those RPMs trying to maintain hwy speeds will kill your gas mileage. Sounds like OD in your future.
    #70
  11. Joz

    Joz What could go wrong?

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    Wow! Those numbers don't look so great. I'm open to suggestions: regear the differential? divorced OD unit? I can't seem to find any married units. Besides, for what I'd pay for a new Gear Vendors unit I could just buy a 6 speed automatic transmission and solve the whole problem. I would prefer to stay with a fully mechanical transmission. A transmission requiring an electronic shift controller just opens a new can of worms.

    Ideas?
    #71
  12. troidus

    troidus Long timer

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    55mph was the prevailing speed limit when both the RV and the Dodge were built, so I'm not surprised that it's geared that way. Maybe a 2-speed rearend could be found, but whether the ratios would be any better is a crapshoot. If the wheelwells are big enough, maybe you could go up a couple of tire sizes to drop your effective rpm at 65.
    #72
  13. Range Motorsport

    Range Motorsport Junk collector

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    A .8 final gear would give you 2050 rpm at 65mph so I would look for an old divorced OD unit for a few hundred bucks. Apparently the Spicer 5831 is a popular unit.
    #73
  14. ghostryder

    ghostryder Long timer

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    In!!!
    :lurk
    #74
  15. Carlo Muro

    Carlo Muro Supercàzzola

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    he likely did mean 800 instead of 8000. If the tires couldn't slip you'd have a mess with said 400 lb.ft engine and 100:1 crawl ratio gearing. Not sure what the weak link would be:lol3
    #75
  16. Nailhead

    Nailhead Free at last!

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    The axle shaft, most likely. DAMHIK.
    #76
  17. Range Motorsport

    Range Motorsport Junk collector

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    "Some Specifications on the Dana 70:

    Max gearing is a massive 7.17:1
    Excellent Locker Selection
    1.5” 35 Spline Shafts
    Max Torque Rating: 8,000 lb-ft or 8,800 lb-ft for the HD
    Nodular Iron Housing"
    -http://www.greatlakeoffroad.com/Dana-70-Disc-Brake-Swap.html
    #77
  18. NDEBT

    NDEBT Long timer

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    I still say it will take a lot of fuel to offset the cost if the gasser is still strong.But honestly I do shit like this too and understand. I Usually wait till I blow the old one up though. If there is anthing you want to know about the chassis PM me the vin. I work for a Ford Dealer so I can get you the specs.
    #78
  19. Joz

    Joz What could go wrong?

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    @NDebt: Thanks for the VIN check offer. I've already run it through and didn't find out much - not that I care. It was an unfinished body (whatever the actual term is) when it left Ford so the VIN isn't as helpful as on a regular truck.

    On the way home tonight, right around the corner from my house I pass a wrecked F250 with a couple'a good old boys tearing it down. It has the 7.3 PowerStroke Diesel. It's been sitting there for a few days now with the front end totally wrecked. Apparently he hit some of those 'safety' barrels on the highway - you know: filled with sand. Anyway it wrecked the front axle, frame, front clip, etc. The long and short of it all is that he's pulling the engine & transmission to put in a 'new' truck he just bought. He's parting out the rest......

    So on a hand shake deal I got dual tanks, all the fuel lines, the filler necks, fuel switching setup - the whole kit! The price was reasonable & I'm happy. If my original (gas) fuel tank is galvanized then I can't use diesel in it. Apparently diesel fuel will dissolve the coating and gum everything up.

    The plan is to stop by on Thursday afternoon and strip it all out!

    SWEET! Funny how things just work out sometimes!
    #79
  20. Nailhead

    Nailhead Free at last!

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    Nice! :clap
    #80