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350 TBI great mpg!

This is a discussion on 350 TBI great mpg! within the Technical / Maintenance forums, part of the General Discussion category; I was driving my 94 Chevy with the 350 TBI yesterday on the highway just to see how many mpg ...

  1. #1
    4/6 dropped Silvy on 22s
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    350 TBI great mpg!


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    I was driving my 94 Chevy with the 350 TBI yesterday on the highway just to see how many mpg I would get and I was surprised. I got 22 mpg ranging from 60 mpg to 70 mph for 123 miles. It only used up 5.5 gallons.

    I measured it by filling the tank, then coming back to the same pump to fill again. All I have is a 4/6 drop and running 265/35 tires on 22s. I am happy with the results. I wanted to see if anyone else has this mileage?
    94 Chevy Silverado 2wd stock 350 K&N CAI no muffler dropped with 4/6 DJM kit rolling 22" Akuza wheels wrappped in Kumho 265/35/22 tires

    95 GMC 2500 2wd longbed 6.5 Turbo Diesel stock 3.73s 14 bolt rear

    2004 trailblazer 4.2 daily driver

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    Can I help you? ksukats57's Avatar
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    Re: 350 TBI great mpg!

    thats pretty good for a TBI, although you should run a whole tank to get the most accurate data.

    FWIW my cousin has a 2005 sierra ECSB 2wd with 22"s and gets 25 on the highway with the 5.3


    2006 Tahoe Z71

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    Registered User bwood's Avatar
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    Re: 350 TBI great mpg!

    My cousin had a 90 RCSB w/ the 5.7 & 3.08's, it was normal for him to get in the low 20's on mpg.

    Later we installed a Edelbrock TBI intake, some cam he got from A-Zone, electric fan, Hypertech chip/thermostat, headers, daul exhaust and 295/60R15's and the mileage was still good if you kept your foot out of it. It dropped on the highway when we put 3.73's in it.
    1998 GMC Sierra SLE 1/2 ton 2WD 305 Vortec
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    Re: 350 TBI great mpg!

    My 94 Sub got 24 on the highway, 18 around town.
    '98 K3500 7.4Vortec/4L80E, airbags, Bosch injector upgrade, Magnaflow exhaust, custom tuned by me!

    Click here for Vortec distributor cap info

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    Registered User x95Tahoex's Avatar
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    Re: 350 TBI great mpg!

    My tahoe is only getting 12mpg. Could it be because I'm using a cheap Bosch O2 sensor instead of a factory one ?
    95 Tahoe 4D, Flowmaster 40, Magnaflow cat/y pipe, TBI mods, TBIChip, Dyna Mod, B&M shift kit, 4.10s, nitto terragrapplers 285/70/17

    09 Silverado 1500 5.3 ecsb, Airaid Jr. Intake, Diablo intune diablew tuned....waiting for tcm support..

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    Registered User bradschevy's Avatar
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    Re: 350 TBI great mpg!

    Quote Originally Posted by x95Tahoex View Post
    My tahoe is only getting 12mpg. Could it be because I'm using a cheap Bosch O2 sensor instead of a factory one ?
    Don't Feel that bad, I'm getting arround 14 average... Maybe I should change some stuff, O2 sensor, sparkplugs? All I know is 20 is great....
    2013 Silverado 1500 ECSB -Black with z71 appearance package, debadged tailgate and doors. 5k HIDs in custom made projectors, K&N CAI, weathertech floormats, access tonneau cover

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    Supporting Member brutal's Avatar
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    Re: 350 TBI great mpg!

    was gettin 9 all around on stock engine

    1997 K1500 Built vortec 355
    transbuilderguy built 4L65E, yank, 14 bolt

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    Registered User jake760's Avatar
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    Re: 350 TBI great mpg!

    I get about 21 on the highway.

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    Re: 350 TBI great mpg!

    Quote Originally Posted by skills4lou View Post
    My 94 Sub got 24 on the highway, 18 around town.
    my 95 is about the same. stock 350

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    Big Daddy 1-8-4-3-6-5-7-2's Avatar
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    Re: 350 TBI great mpg!

    My brother gets 18 highway with his '94 Burb with 7" lift, 4.88 gears, and 36" Iroks.

    My almost stock '96 Burb only gets 14.2
    :-)

    '96 Suburban, 17x9 Helo's, 37" Toyo MT's, 14 bolt sf, 5.13 Yukon by Custom Differentials, Black Bear tune!



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    hucking fates this server FordeatinZ71's Avatar
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    Re: 350 TBI great mpg!

    best i ever got out of my '91 K1500 with 3.42 gears, ext. cab, TBI 350 and 700R4 was 20.

    2004 GMC Sierra SLE Z71 rcsb, 5.3/4L60E/3.73/G80 time bomb...3" lift, tinted 03+ Silverado tails, plasti-dipped 16" wheels (unknown brand), 285/75/16 Thunderer M/T Extremes, Thrush Welded muffler...

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    Re: 350 TBI great mpg!

    When you guys start asking why your mileage dosen't compare to everyone else's we need more info. Specifically what gears in the diff, what size tires, (stock or taller, if taller how much taller) and how you drive.

    I can get 16, 16.5 in town with my 96 and 17 17.5 highway. To get 16 16.5 in town I have to keep it at 2,000 or less but it's possible. (yes it's a Vortec but that shouldn't be much better then a TBI)

    My 03 I have been getting 19.5 average in town. But I haven't been putting my foot down much either. (for those who don't know diesel does get better mileage, just cost more to maintain, and this is just an example).

    The best I have gotten so far is with my 89 Camaro. 23 highway running a little rich. But that lacks the weight of a fullsize and is also geared with 3.08's

    For the two who asked why theirs was so bad I have a couple questions?
    If you have 4.10's that kills gas mileage.
    Do you know what gears you have?
    How well have you keep the truck running?
    When was your last tune up?
    What kind of oil are you running?
    How do you drive?


    03 Silverado ECSB, Dmax, Allison, 3.73 G80
    96 Silverado ECSB, 350, 4L60E, 3.73's Powertrax Locker
    05 Cavalier
    74 Corvette Stingray, 350, 4 speed
    49 F-1, flathead 6, 4 speed, 2wd, unknown rear end. Old rust bucket.

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    hucking fates this server FordeatinZ71's Avatar
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    Re: 350 TBI great mpg!

    Quote Originally Posted by kcb37 View Post

    The best I have gotten so far is with my 89 Camaro. 23 highway running a little rich. But that lacks the weight of a fullsize and is also geared with 3.08's
    there's also a "slight" aerodynamic advantage there...

    2004 GMC Sierra SLE Z71 rcsb, 5.3/4L60E/3.73/G80 time bomb...3" lift, tinted 03+ Silverado tails, plasti-dipped 16" wheels (unknown brand), 285/75/16 Thunderer M/T Extremes, Thrush Welded muffler...

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    Re: 350 TBI great mpg!

    I can't argue with that, the point was that the gears and weight make a difference. That brings me to another thought.
    If you have a 1/2 ton it should get better mileage then a 3/4 or 1 ton, also reg cab short box 2wd 1/2 ton to a crew cab long box 4wd dually.


    03 Silverado ECSB, Dmax, Allison, 3.73 G80
    96 Silverado ECSB, 350, 4L60E, 3.73's Powertrax Locker
    05 Cavalier
    74 Corvette Stingray, 350, 4 speed
    49 F-1, flathead 6, 4 speed, 2wd, unknown rear end. Old rust bucket.

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    Re: 350 TBI great mpg!

    Quote Originally Posted by 94stepside5.7 View Post
    I was driving my 94 Chevy with the 350 TBI yesterday on the highway just to see how many mpg I would get and I was surprised. I got 22 mpg ranging from 60 mpg to 70 mph for 123 miles. It only used up 5.5 gallons.

    I measured it by filling the tank, then coming back to the same pump to fill again. All I have is a 4/6 drop and running 265/35 tires on 22s. I am happy with the results. I wanted to see if anyone else has this mileage?
    That's hard to believe what gears are on your rearend? Plus what more did it bring it up with them rims & tires also were you following a 18 wheeler also was it all downhill?

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    Re: 350 TBI great mpg!

    I get 13-14 highway and 10-11 city and not happy about it at all. I never cruise in it anymore...only when I need to use it..and THAT bothers me. I love driving it but damn it costs a lot. I think my only option is to sell my work car and get me another cruiser....2000 WS6 TA with LS1. I think I could be happy in one of those.
    1993 Chevy 5.7 tbi Z71, vortec heads, GMPP tbi vortec intake, 2" TBI and bored intake, TBI spacer, Comp Cams 08-409-8 XTREME 4x4 roller cam conversion, Hedman full length headers, 3" body lift, 33" tires, Paxton Performance tune (aka 94Blazer383), 4.10's, Hypertech powercharger, built 4l60e.

  17. #17
    73-98 trucks for life...
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    Re: 350 TBI great mpg!

    22mpg to cali and back at 85mph with a/c here.
    78 c10, shortbed/stepside: 5/5" drop, muncie M20, 388 stroker. Playtoy and first vehicle.
    98 gmc x-cab: 5.7L, 17"s, 5/6" drop, flowmaster,K&N, air ride helper bags, kicker sterio.
    06 Honda CBR600F4i: freakin rocket ship
    ----------Disclaimer: I can't spell-----------

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    Registered User Heslekrants's Avatar
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    Re: 350 TBI great mpg!

    I put a 350 Vortec topped off with a TBI in my Son's 90 Camaro and he's getting 25mpg.

    My 99 Suburban was getting 20+mpg on the hwy with the stock motor. I got 25mpg a few times when I was commuting from Austin Tx to Denver Co on a weekly basis for 9 months. That's a 900 mile trip 1 way and sometimes I would drive straight thru without stopping for anything.
    1999 K1500-Int balanced 383, 10:1 pistons,534 lift cam,6"rods,195cc alum heads,1.6RR,welded alum vc,LT4 knock module,,headers,Flowmaster SUV50,highflow cats,drilled/slotted rotors,HID headlight,14Bolt SF 4.10 gears & 13"rear disc

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    hucking fates this server FordeatinZ71's Avatar
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    Re: 350 TBI great mpg!

    [threadjack]Heslekrants, if your son isn't in the Cascade Crew, he should check them out...them or the Pacific Northwest Camaro Club...really good people...[/threadjack]

    2004 GMC Sierra SLE Z71 rcsb, 5.3/4L60E/3.73/G80 time bomb...3" lift, tinted 03+ Silverado tails, plasti-dipped 16" wheels (unknown brand), 285/75/16 Thunderer M/T Extremes, Thrush Welded muffler...

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    Re: 350 TBI great mpg!

    Thats really no suprise. TBI is a very fuel efficent system if its in good working order. You have strong lowend torque, heads that promote lowend torque with the swirl in the intake to help mix the air fuel mixture better for a better burn, a heated intake for better fuel atomization, and its just good. The best I have gotten from mine is 18 running 60-65 but the last I really drove it I was getting a consitant 16-16.5 mpg running 70-75 mph. Not bad for being severely over geared at cruising speeds. 2400-2500 at 75 sucks IMO. I'm hoping that with 35's and the LT4 hot cam I can bring the mpgs up some to around 18-20ish consistantly on the highway.
    1995 Silverado - ported vortec heads, 4L80E, efans, LT4 Hot Cam, Rear disc brake conversion w/drilled and slotted rotors
    1999 NBS Silverdo - transgo HD2 shift kit, 3 inch dynomax ultra flow, Ford keys and 305/70-16 Mickey ATZs

 

 
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