Gear Ratios: Misinformation at its worst.

Discussion in 'Experienced Truckers' Advice' started by Hammer166, Apr 28, 2021.

  1. Hammer166

    Hammer166 Crusty Information Officer

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    And both segments are chasing lower RPM at Cruise, but for different reasons.

    The best BSFC numbers from a diesel occur somewhere on the lower end of the plateau of torque Peak. And they're trying to push the RPM down to lower frictional losses.

    Gasoline engines in automobiles use a much smaller percentage of their total power for cruising. They are also much more efficient with larger throttle openings to reduce intake manifold vacuum. So they operate well below torque Peak in order to allow for those larger throttle openings. By going to more gears with more overdrives, they can keep their final drive ratios low to maintain acceleration while still keeping the very low Cruise RPM.
     
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  3. REALITY098765

    REALITY098765 Heavy Load Member

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  4. REALITY098765

    REALITY098765 Heavy Load Member

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    I guess I am using the bicycle analogy.
     
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  5. REALITY098765

    REALITY098765 Heavy Load Member

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  6. REALITY098765

    REALITY098765 Heavy Load Member

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    What muscle car had 308 gears?
     
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  7. Hammer166

    Hammer166 Crusty Information Officer

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    In the early 80's, Mustang GT and iROC Z's were the "muscle" cars, and they generally had 3.08. Mid 80's 5 speeds started to show up, 3.23 was an option.
     
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  8. Magoo1968

    Magoo1968 Light Load Member

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    Aka snowmobile clutch
     
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  9. SmallPackage

    SmallPackage Road Train Member

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    3.08’s were standard in the 3rd gen firebirds.
    My wife bought her 2nd gen ‘81 in ‘84. It was a low miles trade-in with 301 V8, 3.08’s and TH350. Has had a 400 with 3.42’s since 1996.

    Hence musclecar in quotes. They were for the day.
     
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  10. REALITY098765

    REALITY098765 Heavy Load Member

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    I consider those pony cars ,not muscle cars.
    1970 340 duster 390's
    70 W-30 and buddy's w31 had 390's
    70 stage 1 Buick had 342 cause it had AC, without AC had 364;s
    with lower [higher numerically] available on most of those.
    Even a 68 z28 had 411's
    87GN 342's
    Didn't a B-dart have 456's?
     
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  11. Hammer166

    Hammer166 Crusty Information Officer

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    I bought an 82 Mustang, my first new car. Didn't make it 6 months before it had a 4bbl and dual exhaust. It embarrassed a lot of IROCs and TAs. It gave vettes hell, too, but they could hook up so much better off the line it was tough to reel them back in. Still miss that car.
     
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