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Thread: Highway gears?

  1. #16
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    It just seems high for a stock engine. I get 17mpg no matter what highway/city lol. But mines got the cpi crap.
    For TBI it usually take a-little more modding than a just TB-spacer to get that kind of mileage in my experiences. But every engine is different

  2. #17
    Senior Member bigjsp's Avatar
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    i don't think people really understand the true nature of what a good over drive tranny does. 4.10s with a 0.7 high gear is like a regular tranny and 2.87 except you have a lock up convertor. lowering the gear ratio so the torque convertor doen't stay in lock up will kill milage and put extra heat in your tranny particularly if you tow.

    another thing is what can be done by just bolting on a set of travel wheels and tires. 25'' tall tire vs 27.5'' tire = 10 percent.

    24 to 29 = 20 percent


    for the money the tbi spacer for a gm is the best ever performance enhancement and gas milage increase possible for just about any vehicle

  3. #18
    Registered User wagonmaster's Avatar
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    Quote Originally Posted by bigjsp View Post

    another thing is what can be done by just bolting on a set of travel wheels and tires. 25'' tall tire vs 27.5'' tire = 10 percent.

    24 to 29 = 20 percent


    for the money the tbi spacer for a gm is the best ever performance enhancement and gas milage increase possible for just about any vehicle
    You change your tire size, you change your speedometer. Are you going to compensate for that, too?

    When I sold AEM intakes they would include a throttle body spacer IF they found a horsepower or mileage increase. Guess what, NONE of the GM intakes had one. My opinion, and I have sold and installed hundreds of TBI spacers in various vehicles, is they offer very little performance inprovement. Same as that Tornado POS.

    Intake upgrades, ECM reprogramming, better exhaust. All that together worked really well to improve HP and mileage on every truck, sometimes with truly amazing results.

  4. #19
    Senior Member bigjsp's Avatar
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    Spacer picked up 1 mpg and enough hp on shop truck to gain 3 mph going up the big hill near our shop. Cheap enough and simple enough to try.
    A big hill is almost as good as a drag strip.


    The tornado didn't work.

    The point of the tire size was that before spending money to change gears from 3.73 to 3.42 it would be simpler to just bolt on a different set of tires for a week.

  5. #20
    Zombie Killer 6SpeedBlazer's Avatar
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    Quote Originally Posted by bigjsp View Post
    Spacer picked up 1 mpg and enough hp on shop truck to gain 3 mph going up the big hill near our shop. Cheap enough and simple enough to try.
    A big hill is almost as good as a drag strip.


    The tornado didn't work.

    The point of the tire size was that before spending money to change gears from 3.73 to 3.42 it would be simpler to just bolt on a different set of tires for a week.
    i prefer my t56 and 4.10's i cruise down the highway at 62mph with only 7% throttle.

    then again my motor makes enough low rpm torque to make that possible.

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