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Thread: 94' Z71 gas mileage

  1. #1
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    94' Z71 gas mileage

    What kind of gas mileage should my 94' Z71 with 150k miles get?

  2. #2
    Forum Moderator Boudin's Avatar
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    That depends. I assume you have the 350 and probably have the 3.73 rear end. With any mpg values that one might get, it can vary depending on a lot of factors. Engine size, rear end ratio, driving habits, ac on/off, "tuned up" engine, air filter dirty/clean, etc.

    What kind of mpg values are you getting? Without knowing any details other than what you provided....I would expect maybe 15-17 on highway and 13-15 around town.

    Hope this helps.

  3. #3
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    got a 350 with a clean air filter and the ac off around town and i have 150k miles on it and get 9mpg around town

  4. #4
    Forum Moderator Boudin's Avatar
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    What size tires do you have on the truck? The 9mpg you said seems a little low....but with so many factors involved it could be a simple matter of a calculation mistake due to equipment changes. Before i get into that....Any idea what you are getting on the highway?

    If you change your tire size, you may already know that your speedometer is off. One thing you may have not realized is that it throws off your odometer too. Spending on what tire size you have now and what the original size is, you might either be getting worse than you calculated....or better. If, for example, you are running bigger than stock tires, your speedometer is only registering 60 mph when you are really going 72 mph. This is a difference of 20%. So, your mpg calculation would be off by 20% as well. Now, this would turn your 9mpg into 10.8mpg.

    Have the plugs ever been replaced? Fuel filter?

    I know how much it hurts at the pump....trust me. I drive an 84 3/4 ton and dont have an overdrive tranny. On top of that...I have a 4.11 rear end. On my best day, I might get 12 mpg....but most of the time, it's like 8-9 mpg.

  5. #5
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    My 94 Z71 extended cab has a tonneau cover on it, 31" Wild Country tires, 350, rebuilt transmission... looking at 18mpg on highway and 13mpg in town (I'm lead footed). Bosch +2 Platinum plugs, 3" exhaust and a K&N cold air.

  6. #6
    Full Member mcgwirecom's Avatar
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    I have a'93 5.7L I put on a Airaid K&N air filter and a spacer under the throttle body. I don't think it helped fuel economy. It is basically about 10MPG around town. I remember back when it was new I went on a trip and got about 600 miles on a tank highway. So what is that? Is tank 24 gal?

  7. #7
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    i was wondering the same thing. i just got a 97 gmc sierra xtd cab 4x4 with 350 auto with 123,000 miles. i have only ran one tank thru it and it got 15.2 mpg. thats round town and back n fourth to work. one thing i did notice that i don't like is the weenus fuel tank. it must only hold about 20 gal as i ran it down to about 1/8th of a tank and it only took 15 gal to fill it. i just came from a ford super duty with 7.3 with a 38 gal tank. so this gmc seems like a can watch the gauge go down as i drive!

  8. #8
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    15.2 on a 350 with 4x4 is pretty good IMO. I have a 94 2wd with a 350 and get about that just to work and back thats it.
    1994 white ext cab chevy silverado 5.7 rolling 230k miles
    stock with air filter lid flipped,
    open flowing exhaust to a 40 series flowmaster dumped.
    God Bless America, Support our Troops!

  9. #9
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    Boudin has it about right. I have a 1995 Z71 and my mileage is about what he said.

  10. #10
    Full Member 98chevyz71's Avatar
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    i have 98 350/3.73/intake/headers/cam/tune and i average about 12-16 i like how my truck sounds at wot

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