Fuel millage

Discussion in 'Engine Performance + Maintenance' started by kennythewelder, Aug 14, 2019.

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  1. kennythewelder

    kennythewelder B31-3 (6-G) certified

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    Post your MPGs city- HWY. What year, what engine, mod or OE, what gears you running, and what size tires. Mine is a c1500 97 Vortec, exhaust, tuned for premium, and I get 11 city 16 HWY. 342s and 275/60/15s. I met up with a guy at the gas station last fill up, who clammed 16 city and 20 HWY. Same truck. I said man you must have 273 gears. So post yours and let see what everyone else is getting.
    Thanks in advance.
     
    Last edited: Aug 14, 2019
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  2. Schneider96

    Schneider96 Newbie

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    I average 14.5mpg combined with my mixed weekly commute.

    Have gotten around 19 on long freeway trips.

    5.7 vortec, 96 4x4 4door Tahoe. 3.73s


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  3. smdk2500

    smdk2500 I'm Awesome

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    95 5.7 5 speed 4x4 rclb 2500 265-75-16 4.10 straight pipe no other mods 8 mpg
    95 6.5 auto 4x4 eclb 2500 265-75-16 4.10 3in downpipe 4" from down pipe back S&B air intake 15mpg combined.
     
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  4. Seanthemechanic

    Seanthemechanic Newbie

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    92 scsb with the stock tbi 350 minus a chip, muffler, y pipe upgrade, 3:73’s, built 700r4, 20’s. I get combined almost 15


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  5. Trigger_guard

    Trigger_guard I'm Awesome

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    97 1500. Carbed 5.7 5speed 3.73s 32in tyres 5500lbs wet

    I average 12.8 on 89oc


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  6. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    88 C1500 scsb 5.7 TBI, 170cc/69cc runners, 62cc chamber, 2.02"/1.60" Al heads, 207/213 @ 0.050" .466"/.484" cam (w/1.6 rockers), 46mm bored TB, 61Lb/hr injectors, running @ 28psi, shorty headers, mandrel bent Y pipe, high flow 3" cat, 3-chamber 3" muffler. EBL Flash2 ECM, WB O2, with EGR delete and Hyway lean cruise enabled, stage 2 (600hp) 700r4 trans, 4.11:1 gears. I get around 13-15 MPG and don't have a city to drive in, LOL. Who cares it's fun to drive!

    Edit - stock 235/75/15s
     
    Last edited: Aug 14, 2019
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  7. 98chevy2500SS

    98chevy2500SS OBSessed

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    '97 Chevy K1500 F44 Z71 ECSB: 5.7 Vortec, 4L60E, 3:73s w/ G80, duals w/ single dual-in/dual-out stainless Magnaflow muffler, LT285/75r16 AT/MT hybrid - 12-14 mpg together.

    '98 Chevy K2500 Z71 ECSB: 5.7 Vortec, 4L60E, 4:10s, true dual exhaust w/ stainless Flowmaster 40s, LT265/75r16 - 12-13 (guessing) mpg together.
     
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  8. L31MaxExpress

    L31MaxExpress I'm Awesome

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    1997 Express 1500 5.7/4L60E and 3.42s with P295/50R15s would get 18 mpg highway and 12-13 in-town. Tune, Thorley Tri-Ys, 395 marine cam, EGR delet, Marine intake, still 18 mpg highway. Swapped to a 4L85E and 3.73 9.5 14-bolt. Still 18 mpg highway and 10-11 in town. Swapped full 1 ton running gear under it with a 3.73 gear and LT265/75R16s. 18 mpg highway and 10 mpg in-town. Swapped the heads for Assault Racing 205cc and a 218/228 @ .050 cam with 1.6 rockers. Same MPG. Swapped in 5.13 gears. 13 mpg in-town and 17 mpg highway. Currently building an 11:1 383.

    1999 Tahoe...305 with a Lunati HE 268 cam, long tube headers, 2.25" exhaust piping, volant CAI. S10 converter, 3.42 gears and P305/50R20s. 15 mpg city and 23 mpg highway. Swapped the 305 out for a Mercruiser 425 HO cammed 8.1/4L80E when the 4L60E died. Using a 4.3 4L80E van high stall converter. 8.1 is stock save for the cam and shorty headers. 12 mpg city and 18 mpg highway. Cruises 1,800 rpm @ 70 mph.

    All MPG values are with lean cruise enabled at about 16.5:1 air/fuel ratio on flat road.

    1983 G20 van with an 8.1/4L80E/3.08 gears. GM 454/502 HO cam, 2nd gen camaro long tubes and tune. P295/50R15s. 15 mpg city and 19 mpg highway.

    A wideband and real time tuning really helps save fuel.

    That being said TBI swirl port head engines usually came paired with taller 2.73 or 3.08 gears and are the mileage champs of the GMT400s out on the highway unloaded. My old 83 G20 with a TPI on a 350 TBI with a GM LT4 cam and tri-y headers would often pull 22-23 mpg highway.
     
    Last edited: Aug 15, 2019
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  9. BNielsen

    BNielsen I'm Awesome

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    1996 Chevy K2500 Extended cab short bed, Vortec 454 backed by a 4L80E with 3.73 gearing on 285 BFGs; last I checked I was getting 10.5 city, not sure what highway mileage would be but I expect 12-13.

    There's definitely room for improvement with the 0411 though, I just need to quit being lazy and order HPTuners so I can get to adjusting.
     
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  10. Wade

    Wade I'm Awesome

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    12city- 15HWY. 1994, 350 TBI/4L60E , Ultimate TBI mods, TBI spacer, open element filter with cowl induction hood. vette servo, Long tube headers, 2 1/2" true dual exhaust with 12" glasspacks. 3.73 gears, 295/75/16's
     
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