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29632Re: [classicrv] Turbocharging

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  • Scott Williams
    Mar 3, 2008
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      First of all, none of the discussion about turbocharging has been very
      relevant to diesels. A diesel doesn't have the same issues as a gas
      engine - compression ratio is a big deal with turbos on gas, not so with
      diesel, for instance. A diesel can make more power with a turbo, even
      without injecting additional fuel - I know of folks who've tested the
      theory by adding a turbo to their diesel Mercedes and didn't change
      anything else. Diesels just work SO differently than cars. A car needs
      an "ideal" air/fuel ratio (around 12:1 or 15:1, something like that) to
      make the most power. To make more power in a diesel, you just keep
      adding fuel, and are only limited by exhaust gas temperatures. Just
      another point to illustrate that they are totally different animals
      (turbos on gas vs. diesels.) I have the McInnes book on turbos, not a
      diesel book.

      As I said, a diesel can make more power with the addition of a turbo,
      even when the injection pump is left as-is (in other words, without
      turning up the fuel.) Also, with the turbo, you don't lose HP when you
      go up to higher altitudes, or when the air is thinner (like on hot days.)

      This isn't an argument for adding a turbo to any old diesel engine,
      though. I would say adding a turbo would be best accomplished if an
      engine was offered with a turbo as an option. Diesel engines are so
      much more difficult to hold together that I bet it would be difficult
      for a do-it-yourselfer (for example, they shake so much more than a gas
      engine, any welding done on exhaust manifolds to add a turbo mount would
      be likely to crack.)

      Just my (perhaps poorly informed) opinions.

      Scott in Penfield NY

      chris tryba wrote:
      > this sounds spot on....any idea what would be an "easy" swap of my current 555(triple nickle) cummins??? im lookin to take it out and replace it with a more modern diesle as mine seems to be haing new issues....it has run great for the 4 years ive had it...this past week...it is seeming to "bog down"
      >
      > any ideas would be great..
      >
      > chris
      >
      > Ron Mitchell <rmitchel@...> wrote:
      > At 03:59 PM 03/01/2008, you wrote:
      >> my issue isnt power....its mpgs!!
      >
      > I don't think turbocharging would gain you enough efficiency alone to
      > be worth the cost. At best, I'd expect 1-2 mpg increase, if any. Its
      > big advantage is being able to boost the power, without costing an
      > arm & leg in efficiency, as most superchargers do, especially the
      > Roots-type that we're used to seeing on top of dragsters. Those guys
      > are measured in gallons per mile. When not in use, a turbocharger
      > just sits there, doing nothing and costing nothing.
      > Your best bet for efficiency is to install a nice dual exhaust
      > setup to increase the airflow efficiency, get a good carburetor on
      > it and keep it in top tune. Change the air filter regularly and
      > switch to synthetic fluids all around. While synthetics are more
      > expensive, they last longer, have lower friction and will help
      > increase the mpg numbers. All of this might gain you 2-3 mpg and make
      > the cost worthwhile over the long run. Since many RV's sit for long
      > periods, the synthetics also have better adhesion properties and help
      > prevent corrosion to the drive train. There's no way you're going to
      > take a 1970's 14,000+ GVRW vehicle and increase it's mileage from
      > 8-10 to15-20. Not going to happen. Remember, you're pushing 2 4x8
      > sheets of paneling through the air at 50+ mph. But, at $3.00+/gallon,
      > even 2-3 mpg would help a lot. You have to measure the cost vs the benefits.
      >
      > Ron
      > 76 Coachmen
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