Insight into Dyno and blowby results

Discussion in 'Freightliner Forum' started by zablon, Feb 17, 2015.

  1. zablon

    zablon Bobtail Member

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    Feb 16, 2015
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    Hi not sure if this would be the right place for this but shopping around for a used truck i was handed the results sheet of a dyno run performed on one candidate. The truck is a former Prime company 2012 cascadia, 360k miles, 455 rated hp DD15 def engine, 3.36 rears, and 10 speed trans.
    Dyno operator indicated blowby is -3.09, tested max actual hp put out was 446 and that everything was within specs.
    Now there's alot of info missing like torque figures, engine load, egt, so i will get a ecm printout and also take it to another shop that could give a fuller picture of whats going on with this engine including an oil analysis. But before that's arranged what do you members of this forum make of these numbers/results.


    Dyno.jpg
    Dyno_b.jpg
     
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  3. jdp2011

    jdp2011 Bobtail Member

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    Dec 12, 2011
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    Only 9 hp loss at the wheels. Wow
     
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  4. spyder7723

    spyder7723 Road Train Member

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    Never trust a used truck salesman. Get your own dyno at a shop of your choosing. If they won't age to you taking it somewhere else, don't deal with that dealer.
     
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  5. zablon

    zablon Bobtail Member

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    Feb 16, 2015
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    True, i am always skeptical of any sales person as i understand they are doing their job...sales...which unfortunately for the most part doesn't fully coincide with most buyers interests. Because this truck is being sold at a freightliner dealership, i will ask the dealer if it would it be possible to do another ppi ( even if i have to pay for it) with me present at the shop to observe the mechanic check it over and dyno it again or should i just take it to an independent shop for this type of inspection?
     
  6. spyder7723

    spyder7723 Road Train Member

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    Take it to an independent shop. Never use the salesman's shop or mechanics. Yes, you will have to pay for it, but I'd rather spend five hundred to find out why not to buy a truck, than spend fifty thousand on a truck with problems.

    I wouldn't trust that dyno. There is just no way it's only losing 9 hp from the engine to the wheels. That tells me either it's completely rigged to fool you, or the mechanic that did the test didn't do it right. A lot of energy is lost in the drive line. I'm sure technology has improved but it used to be expected to lose 20 percent on perfectly good running engine. Hell, just the fan coming on could suck up 50 hp.
     
  7. jdp2011

    jdp2011 Bobtail Member

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    Dec 12, 2011
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    I think the only way the dyno results could be accurate is if the engine was up rated to 500 hp. Otherwise I agree with Spyder7723 take it to a different shop.

     
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