Fuel economy on a 440 maybe 493. With MPFI and T56 magnum

Fuel and Air Systems

  1. dodgekyle87

    dodgekyle87 Member

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    I’ve got a dumb question FUEL ECONOMY

    440 and holley terminator multi-port efi with timing control
    Possibly 493 stroker kit

    definitely aluminum heads
    T56 magnum wide ratio with .50 6th gear

    3.73-3.55 gears

    what you think fuel economy wise with this setup.
     
  2. 747mopar

    747mopar FBBO Gold Member FBBO Gold Member

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    I have pretty close to that setup only carbureted and get 19mpg.
     
  3. 493 Mike

    493 Mike FBBO Gold Member FBBO Gold Member

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    14 MPG.
    Mike
     
  4. Nate S

    Nate S Well-Known Member

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    There are a huge number of variables, you’ve made a couple better but cam, timing with vacuum advance, and compression ratio are still unknown to us. Oh, weight too. If all that is stock-ish you’re probably at 14, on the highway with fi and that tranny maybe you hit 19. Most people never actually check their odometers with gps either, their error is different than speedo error. Add up to 20% error to most observations.
     
  5. dodgekyle87

    dodgekyle87 Member

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    It will have a stock or vary mild cam, timing is computer controlled, not vacuum advance so i assume optimum timing on the fly per demand Using holley dual sync. 1969 coronet so there’s the weight. And compression I’m looking at around 10:1 with aluminum heads

    as for speedometer I will use Dakota digital with the pulse signal from the t56 mag pickup. I have this setup in another car and found it to be accurate down to about half a mph



     
    Last edited: May 13, 2021
  6. dodgekyle87

    dodgekyle87 Member

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    You using computer controlled timing?
     
  7. Nate S

    Nate S Well-Known Member

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    You’ve got the deck about as stacked in your favor as you can get it. I’d guess 15 / 18 city / highway.
     
  8. 68Moparmaniac

    68Moparmaniac Well-Known Member

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    Why worry about fuel economy? Dude your talking about a big block Mopar tucked in a body style that's about as streamed lined as a brick. Unless you opt out for a more modern drivetrain with all the bells and whistles your looking at maybe 12-14 city depending on your driving style.. highway 16-18...
    I guess what I'm saying is you don't buy a big block 69 B body for gas mileage. :drinks: You want gas mileage get a Prius...
     
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    • JerseyJoe

      JerseyJoe Well-Known Member

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      I didn't build a 493/4 speed MoPar to save gas. You won't either once you stick your foot in it.
       
    • 747mopar

      747mopar FBBO Gold Member FBBO Gold Member

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      I see your point to a degree, myself I bought mine to drive the crap out of it.. going from 12mpg to 19mpg sure encouraged putting more miles on it.:thumbsup:
      No, it's all old school. Mine is a 456" stroker, 452 heads, 9.8:1 compression, 750QF DP, mild cam (1,800-5,800 rpm), a Viper T56 and 3:55 gears.

      I'll warn you right now that you really need to put a lot of thought into your camshaft with that .50 6th... It's ridiculous! The 19mpg that I stated was with 4:30 gears in it and it's an accurate number as I have a GPS speedo plus I figured it up during a long haul to Canada (6hrs of freeway). The 4:30's put it in the sweet spot on the freeway (2,000ish) but really slowed the car down, you were shifting constantly. 3:55's work the best on my car but 6th is now only for freeway cruising and even at that I'm doing 80mph @ 1,800 rpm. I haven't figured mileage up since but I'd be willing to bet it's worse now, 1,800 is really getting borderline where it hummed right along at 2,000rpm.
       
    • slepr1

      slepr1 Well-Known Member

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      Somewhere between 'I must have a gas leak" and 'holy shit I can see the needle drop'.
       
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      • Curiousyellow71

        Curiousyellow71 Well-Known Member

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        Our 510 with 3.23 used to get 21 with a best of 23 average on a 110 mile trip. The combination makes a big difference. It's not so economical now but my smile is bigger then saving a buck at the pump.:lol:
         
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        • ckessel

          ckessel Well-Known Member

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          Other than the engine specs and diff ratio, one of the biggest influences on mileage is that appendage at the end of your right calf. Can you walk with a normal gait or is there so much lead in it that you drag it across the floor when walking?
           
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