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05-10-2013, 06:17 PM | #1 |
Registered User
Join Date: Sep 2009
Location: Beaverton, OR from WA State
Posts: 1,515
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Need some real numbers, MPG...
I have been following a few peoples' build threads and I am looking for some good solid numbers on economy. I'm talking daily driven, mixed, hwy, city, anything. Also, how the truck and engine is configured. I have an '83 4x4 3/4Ton and it will be getting an LQ4 and an NV4500, might even regrear it from 4.10 to 3.73. I am trying to estimate what my economy will be. My intent is to inject it with a 4bbl manifold drilled for injectors, and an air-only throttle body on it. Maybe a mild cam, looking at the SDPC HT1 cam. Specs: HERE Also, LQ9 flat top pistons are a possibility.
I am sure, going from the old carb'd 400sbc to an LS will be a big change and there will be a period of time when the skinny pedal gets a workout, but I am really interested in what kind of economy these engines are getting in our old iron.
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Devin 1983 GMC High Sierra 2500, 4x4, RC/LB, 400 S.B., SM-465, NP-208, Corporate 10 bolt & 9.5" 14 bolt 1996 GMC Sierra SLE 3500 DRW, 4x4, EC/LB, Vortec 454, NV-4500, BW-4401, AAM 925 & AAM 1050 1997 GMC Sierra SLT 1500 4x4, Z71/F44, EC/SB, Vortec 350 My Introduction with my '83s History New Daily, the '96 |
05-10-2013, 07:06 PM | #2 |
Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: Need some real numbers, MPG...
I get 17 mpg average on my C20 Burb with a 5.3/4L60E, 6.0L & yours being 4x4 will be lower, Im guessing around 13-14mpg as a realistic average.
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05-12-2013, 09:25 AM | #3 |
Registered User
Join Date: Jul 2011
Location: Mt Brydges Ontario
Posts: 181
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Re: Need some real numbers, MPG...
I'm in the process also of putting in an LS in a 2wd 70. However my 67 with a fairly healthy 408 smallblock and a 700R4 with 3.42 gears knocks off 17 on the hwy.I'm going the LS way just because I got a whole low mileage 2000 truck for $600. It's just cheaper for me. Your mileage will increase but not by a huge amount.If your drivetrian is in good shape now I wouldnt do a LS swap completely based on fuel mileage.But an LS sure runs nice.In my opinion the symplicity of your current setup is worth something too.
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05-19-2013, 04:11 AM | #4 |
Registered User
Join Date: Sep 2009
Location: Beaverton, OR from WA State
Posts: 1,515
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Re: Need some real numbers, MPG...
Anyone else? There are a ton of our classic steel trucks rolling around with LS mills...they finish their builds and quit reading this section?
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Devin 1983 GMC High Sierra 2500, 4x4, RC/LB, 400 S.B., SM-465, NP-208, Corporate 10 bolt & 9.5" 14 bolt 1996 GMC Sierra SLE 3500 DRW, 4x4, EC/LB, Vortec 454, NV-4500, BW-4401, AAM 925 & AAM 1050 1997 GMC Sierra SLT 1500 4x4, Z71/F44, EC/SB, Vortec 350 My Introduction with my '83s History New Daily, the '96 |
05-19-2013, 05:37 AM | #5 |
It's alsways something.....
Join Date: Nov 2008
Location: Douglasville GA
Posts: 1,171
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Re: Need some real numbers, MPG...
One of the issues, especially with the earlier models (mine is 71 blazer) is that a lot of us are cruising around with LS power, but don't have a working speedometer/odometer. A board member has figured a solution and many are getting started adapting a S10 electric speedo into the 67-72 instrument panel. Stay tuned, MPG info will be coming when the ability to calculate becomes available.
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1968 RS Camaro 'Vert Matching number 327 and M21 Muncie 1968 C10 Black with red interior and orig paint. 5.3 / 4l60e,3:73 POSI 17" Torq Thrusts 1968 CST 514 Red with black interior. Buddy Buckets, Factory A/C, PS, PB- 20" AR custom shop TT, 5.3 and 4l60e |
05-19-2013, 01:11 PM | #6 |
meowMEOWmeowMEOW
Join Date: Sep 2009
Location: MKE WI
Posts: 7,128
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Re: Need some real numbers, MPG...
I get 13-15 local and up to 17+ on the highways locked up around 60. I have a decent amount of drivetrain to turn, so I think the numbers are decent all things considered. Once I'm not running drag radials on the back, my mpg will go up a tad too.
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'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD
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05-19-2013, 02:48 PM | #7 |
Registered User
Join Date: Sep 2009
Location: Beaverton, OR from WA State
Posts: 1,515
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Re: Need some real numbers, MPG...
chuckmc8, I saw that cluster thread and it is fantastic. There is a lot of work that went into it and I think it is great that 67-72 has such a OEM looking solution. 81+ has one from the factory with the 90-91 V-series clusters, they technically fit back to '73 but are cosmetically incorrect.
BR3W CITY, say your build recently, great looking truck. Next to my '83 I spent a lot of time with my dad in his '65 on the farm, such a great truck.
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Devin 1983 GMC High Sierra 2500, 4x4, RC/LB, 400 S.B., SM-465, NP-208, Corporate 10 bolt & 9.5" 14 bolt 1996 GMC Sierra SLE 3500 DRW, 4x4, EC/LB, Vortec 454, NV-4500, BW-4401, AAM 925 & AAM 1050 1997 GMC Sierra SLT 1500 4x4, Z71/F44, EC/SB, Vortec 350 My Introduction with my '83s History New Daily, the '96 |
05-23-2013, 04:38 AM | #8 |
Registered User
Join Date: Sep 2009
Location: Beaverton, OR from WA State
Posts: 1,515
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Re: Need some real numbers, MPG...
Bump
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Devin 1983 GMC High Sierra 2500, 4x4, RC/LB, 400 S.B., SM-465, NP-208, Corporate 10 bolt & 9.5" 14 bolt 1996 GMC Sierra SLE 3500 DRW, 4x4, EC/LB, Vortec 454, NV-4500, BW-4401, AAM 925 & AAM 1050 1997 GMC Sierra SLT 1500 4x4, Z71/F44, EC/SB, Vortec 350 My Introduction with my '83s History New Daily, the '96 |
05-23-2013, 12:57 PM | #9 |
Truck and auto performance nut
Join Date: Feb 2007
Location: McKinney,Texas
Posts: 3,848
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Re: Need some real numbers, MPG...
My 4600-4800lb TrailBlazerSS with 4.10 gears gets 12 around town, 14 average, with 16-17mpg being about tops for any highway mpg at 70+.
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Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken |
05-23-2013, 02:10 PM | #10 |
Registered User
Join Date: Nov 2012
Location: Salt Lake City, UT
Posts: 520
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Re: Need some real numbers, MPG...
I daily drive my truck. It's a 1985, 3/4 ton, long bed, lifted with 33 inch tires and 4.10 gears. I have a stock 5.3 hooked up to the stock th400. I get 11 mpg.
My milage is bad due mostly to my gears, 3 speed trans, and tires. It's better than the 7 mpg I was getting from the stock 350 though. When I put an overdrive trans in it, that should help a lot. |
05-24-2013, 08:13 AM | #11 |
1965 Chevy C10, 2005 4.8L/4l60
Join Date: Aug 2004
Location: DFW Texas
Posts: 8,546
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Re: Need some real numbers, MPG...
I have a 4.8/4l60e in my 65 and I get an average of 15 city and 19+ hwy. I have gotten 20.5 when there wasnt much wind. these are at 65 and I dont hot rod my truck ( why would i with a 4.8 right?)
If mileage is what your looking for in a big truck like that get a Cumins and a nv4500 with propane injection. your truck is huge and you unfortunately wont see the mileage most of the ls is known for for swaps.
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Clyde65 Rebuild of Clyde http://67-72chevytrucks.com/vboard/s...84#post8338184 69 Aristocrat Lo Liner build http://67-72chevytrucks.com/vboard/s...84#post7561684 support our troops! |
05-24-2013, 11:11 AM | #12 |
Registered User
Join Date: Nov 2001
Location: Springfield, MO
Posts: 2,939
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Re: Need some real numbers, MPG...
I will be able to report back after we start on the power tour. In stock form I did pretty good 18 - 20 but after a cam it dropped now I have a turbo but I am hoping that doesn't hurt during normal highway driving. I have also added a T56 but lowered my rear gear to 4.11:1. Time will tell.
These trucks are heavy and the frontal area is huge, the drip rails don't help matters any. Realistically I would love to pull over 20 mpg and it might be possible but speeds over 70 I am afraid we will run into that wall. I believe I have things dialed in good for this trip but again with my weight I bet I will still suffer.
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Dave 1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap 1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?) "A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome". "If it doesn't fit force it...If it breaks then it needed to be replaced anyway!" |
05-24-2013, 11:27 AM | #13 |
Registered User
Join Date: Apr 2013
Location: Douglasville, Ga
Posts: 212
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Re: Need some real numbers, MPG...
Im getting right around 20 in mine, its stock and i drive like a granny...lol 65 tops in most cases, and a lot of back roads at 50ish.
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68' c10 stepper 5.3/4L60e Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=578917 |
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