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Gears in relation to MPG

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by InSearchofAk5, Jul 24, 2001.

  1. InSearchofAk5

    InSearchofAk5 Registered Member

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    Say you have 33" tires... if you have 4.10 gears wouldnt your MPG be higher than if you got say 4.56 gears??
    So higher your axle gear ratio the less mpg you get??
    Thanks
     
  2. Triaged

    Triaged 1/2 ton status

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    You will get the best mileage when you keep the motor withen its range of best efficncy. That is generally around 2400 RPM for a SBC (depending on engine mods). Because of this 4.56 gears will prob get you more city mileage and less on the Hwy than the 4.10.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
     
  3. ftn96

    ftn96 1/2 ton status

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    Ditto![​IMG]

    Beer!!!! Its not just for breakfast anymore!!.[​IMG]
    <a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
     
  4. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color=blue>Also just because the motor is spinning slower DOES NOT mean you will get more mileage. If your spinning in too low of an RPM range the motor cant produce enough torque to keep you moving so you press the [​IMG] pedal more. Oh yeah dont expect good mileage from these trucks, they're heavy and have poor areodynamics. We need more info, what trans do you have, what motor? Where do you use it moslty (highway or street)?</font color=blue>
     
  5. InSearchofAk5

    InSearchofAk5 Registered Member

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    Well i was thinking in terms of a tacoma, cuz thats what a friend has and hes getting lockers and gears soon and he has 33" tires. He wants the best MPG for city driving.
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Does it have a V8 in it? If so, I'd say 3.73s would most likely work. I'd want 4.10s. There isn't that much difference anyway. That's for 33s only though, bigger tire, more gear.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  7. solowookie

    solowookie 1/2 ton status

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    OK guys, highway speeds between 65 and 80, 700r4 tranny, what gear ratio would you go with??? (33" tires) I'm thinking 4.10's with the OD (that is still only 2200 RPM's at 75 with the OD).

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     
  8. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color=blue>Jeff go for 4.56. Figure that into the formula, it will bring your RPMs up a little more where they should be. If your going from 3.42s or 3.73s, theres no point in only going to 4.10.</font color=blue>
     
  9. RESTORE89

    RESTORE89 1/2 ton status

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    not sure what my rpm is cause no tach, but had 3.07 gears and it would not stay in OD even at 75 on highway, and got about 13 mpg, changed to 4.11'S and now it runs great on the highway in OD and gets almost 17mpg and i am running 33/12.50's. not to mention the great low end torque. just depends on how much highway driving you do. if mostly around town and off road "BIGGER IS ALWAYS BETTER" works for gears to not just motors


    It needs a bigger motor.
    what's in it now?
    doen't matter it NEEDS A BIGGER MOTOR
    89 350tbi/700r4h/np208/4.11's
     
  10. Itali83

    Itali83 1/2 ton status

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    What is the web site for this gear calculator?? I wanna figure out my rpm's Thanks.
    Ben 87 Jimmy
    <font color=blue>Rust=Bad</font color=blue>
     
  11. 90blzr

    90blzr 1/2 ton status

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    <a target="_blank" href=http://www.ring-pinion.com>www.ring-pinion.com</a> click on calculators at the top.
     
  12. solowookie

    solowookie 1/2 ton status

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    <a target="_blank" href=http://www.4lo.com>http://www.4lo.com</a>

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     
  13. dumbfounded

    dumbfounded 1/2 ton status

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    The mileage will depend on how and where you drive. If you're in the city most of the time a numerically higher gear will get better (if you can notice) on the highway a numerically lower gear is better (on flat ground). Another big factor is where you're engine makes its power and torque. If you're turning low revs and you have a mild to wild cam it won't do anything but drink b/c you'll have to give it more gas and get out less. But if you have a low end cam you'll be more efficient at lower revs and won't take all that much throttle to move down the road. But on a normal level road the lower the revs the better the gas mileage (just plain physics). So when someone is rebuilding an engine you really need to think about what you need. Not what will give a cool exhaust note or what sounds cool in conversation. Carburation is another huge factor. A 2bbl will drink to holy hell b/c the 2 barrels are bigger than the 2 smaller ones on a 4 bbl (if you can keep your foot out of it). But EFI with an od tranny and 3:55 or 3:73's will be gas friendly.

    Love, Peace, and Hair Grease...........
     
  14. riz

    riz 3/4 ton status

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    <font color=purple> So am I correct t osay that 4:56's would be perfect for a 700 tranny and 35's ????

    L8r,
    . Riz . <a target="_blank" href=http://www.geocities.com/rizmonkey>www.geocities.com/rizmonkey</a>
     
  15. Itali83

    Itali83 1/2 ton status

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    Thanks a ton!
    Ben 87 Jimmy
    <font color=blue>Rust=Bad</font color=blue>
     
  16. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    65mph - 80mph.... hmm I'm no psychic but I can foresee speeding tickets in your future no matter what gears you use! [​IMG]

    I removed my quote so gay, vegetarian, minority, eco-nazis who love Jesus, nuke spotted owls, vote Gore and smoke medical marijuana won't be offend.
     
  17. riz

    riz 3/4 ton status

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    <font color=purple> 80 m.p.h. IS the speed limit right ? LOL!

    L8r,
    . Riz . <a target="_blank" href=http://www.geocities.com/rizmonkey>www.geocities.com/rizmonkey</a>
     
  18. solowookie

    solowookie 1/2 ton status

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    <blockquote><font class="small">In reply to:</font><hr>

    65mph - 80mph.... hmm I'm no psychic but I can foresee speeding tickets in your future no matter what gears you use!

    <hr></blockquote>

    hey, not all of us live in CA where the have those really SLOW speed limits! LOL [​IMG]

    speed limits here on the interstate are 75 (I go 80 in a car ALL the time and drive right by cops and they never give me a second look), and the secondary roads are ususally 65 so 65 to 80 is the range that I usually drive in. it is not really speeding that much over here, just 5 over. [​IMG] (lucky me, maybe it is because there really isn't any people in Wyoming, all we gotta do is watch out for the sheep and the cows. if your rigs big enough they just go splat anyway)

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     
  19. Thunder

    Thunder 3/4 ton status

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    Not where i live. The cops hardly look at you unless you are doing over 80 (speed limit is 75) . We can use detectors too.
    Love my 3.73s and 31" tires on the interstate.

    <font color=orange> You are just jealous, because the voices only talk to me.</font color=orange>
     
  20. riz

    riz 3/4 ton status

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    <font color=purple> Detectors are illegal here !

    L8r,
    . Riz . <a target="_blank" href=http://www.geocities.com/rizmonkey>www.geocities.com/rizmonkey</a>
     

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