The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 07+ Chevy and GMC Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 06-09-2011, 10:42 AM   #51
Otsa580
I Love Rusty Chevys
 
Otsa580's Avatar
 
Join Date: Jan 2009
Location: Omaha, NE
Posts: 617
Re: what are you guys getting for mpg?

My 2010 Silverado ext cab 5.3 4x4 with 3.42's averaged 18 mpg at 75 mph on a 600 mile trip. In town which is 60/40 highway driving I average 15. I do not drive with a light foot because of hills and traffic. The truck has 5000 miles so she is hardly broken in.

I seem to get over 20 mpg at 60-65 but have yet to take the highway on a long trip.
__________________
1969 K5 Blazer
1997 1500 Silverado Ext Cab Z71
2010 1500 Silverado Ext Cab Z71
Otsa580 is offline   Reply With Quote
Old 06-09-2011, 11:51 AM   #52
HEI451
Account Suspended
 
Join Date: Mar 2011
Location: Yerington, Nevada
Posts: 864
Re: what are you guys getting for mpg?

The whole mileage game is linked to air/fuel ratios, and engine performance packages.

That said, with a cruise air/fuel ratio of say, 14.5:1, 60 mph would use LESS air/fuel flow than 75 mph. Any engine that uses less air to run, such as those with smaller displacements and air flow passages in the head, such as Honda, will get better mileage than other engines that are larger and have larger air flow passages, such as the old 153 Nova inline 4 cylinder.

One deviation to this rule is carburetor vs EFI systems. A carburetor relies on air flow past set orifii to pull the fuel into the engine, and that fuel is in the form of somewhat large rain droplets. EFI, on the other hand, uses pressure technology, which injects a more precise volume of fuel, doesn't rely on vacuum as the carb does, and the fuel is injected as a very fine "London fog" of a vapor.

So, smaller displacement, lower total air flow, more finite handing of the fuel/air mixture and fuel in a vapor form, over a giant rain drop = better volumetric efficiency, better mileage.
HEI451 is offline   Reply With Quote
Old 08-12-2011, 10:03 AM   #53
drew86
Registered User
 
drew86's Avatar
 
Join Date: Mar 2009
Location: Flo-rida
Posts: 40
Re: what are you guys getting for mpg?

I think there is something to be said in the difference in weight of wheel and tire combos also.I even experienced a slight loss in mpg's going from factory 17's to factory 20's.I also had a set of 20x10 kmc's with 305/50's for about 3 years on my 07,and they were definitely the worst.I thought they would be better with the taller tire.My truck is 2wd with the 5.3 and 3.73 gear.Averaged 13.5 with the kmc's,15.2 with factory 20's,and 16 with the 17's.

Last edited by drew86; 08-12-2011 at 10:04 AM. Reason: spelling
drew86 is offline   Reply With Quote
Old 08-12-2011, 10:40 AM   #54
piecesparts
Parts and more parts
 
piecesparts's Avatar
 
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,829
Re: what are you guys getting for mpg?

Quote:
Originally Posted by drew86 View Post
I think there is something to be said in the difference in weight of wheel and tire combos also.I even experienced a slight loss in mpg's going from factory 17's to factory 20's.I also had a set of 20x10 kmc's with 305/50's for about 3 years on my 07,and they were definitely the worst.I thought they would be better with the taller tire.My truck is 2wd with the 5.3 and 3.73 gear.Averaged 13.5 with the kmc's,15.2 with factory 20's,and 16 with the 17's.
I would say that for the most part the difference would not be the rolling weight, but the diameter of the tire. The amount of power that is needed to roll a 32" tire is more than what would be needed to roll a 28" or 29" tire. My new truck had factory 32" tires and now I have 30.4" tires on it. It did make a difference to the acceleration, not to mention the wheel well clearance.
__________________
Frank
piecesparts is offline   Reply With Quote
Old 08-12-2011, 10:48 AM   #55
rpmerf
Registered User
 
rpmerf's Avatar
 
Join Date: Feb 2011
Location: Rosedale, MD
Posts: 212
Re: what are you guys getting for mpg?

1970 c20 custom camper 350 8:1 compression, slightly more aggressive cam, 3 speed 4.56 rear 235/85R16 tires

I only measured it once, but I also was leaking gas out of the gas cap so I don't know how accurate it is. It was all highway, mostly around 65, but a few times I found myself doing 75 and a few times I took it up over 90. I got about 12mpg.

A/F ratios are very important, so I plan to install a set of A/F ratio gauges one day to get it tuned in as precise as a carb from the 70's can be tuned. Another big factor that problems almost all cars is fuel atomization. Liquid fuel does not burn, only atomized fuel. There are alot of crazy ideas out there like putting a screen below your carb or tapping the intake ports to help swirl the A/F mixture better.
__________________
1970 C20 Custom Camper 350 Auto
rpmerf is offline   Reply With Quote
Old 09-06-2011, 04:12 PM   #56
KMK454
Registered User
 
KMK454's Avatar
 
Join Date: Jan 2007
Location: USA
Posts: 443
Re: what are you guys getting for mpg?

With those MPG numbers, they may as well have nixed the 5.3 with DOD and gone for the old 5.7 or 6.0 mill with more horsepower and torque. At the end of the day, it's a two and a half ton brick designed to do work; cutting power for tenths of an MPG isn't worth it, and while there are cost savings to be had, the truck has to be driven tens of thousands of miles over the course of many years to see worthwhile savings from going with a 5.3 over a 5.7 or 6.0.
__________________
Kurt
Instagram: @kurtkphoto
1978 C10 Silverado
1991 Camaro B4C
KMK454 is offline   Reply With Quote
Old 09-06-2011, 11:55 PM   #57
piecesparts
Parts and more parts
 
piecesparts's Avatar
 
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,829
Re: what are you guys getting for mpg?

I can say that the 5.3 that I now have is stronger and has more roadability than the 91 that I sold, when I bought the 2011. The computer tune may have something to do with that. It is a strong engine and the acceleration is much better. The gain in gas mileage from the 91 is not so noticeable, but the performance is.
__________________
Frank
piecesparts is offline   Reply With Quote
Old 09-13-2011, 05:38 PM   #58
LEEVON
Registered User
 
LEEVON's Avatar
 
Join Date: Jul 2006
Location: Nixa, MO (Springfield area)
Posts: 4,535
Re: what are you guys getting for mpg?

I surmise that we can thank federal regulation for the DOD's, AFM's and other do-nothing addons. Enjoy it while you can though, 54.5 mpg by 2025!
__________________
'18 Silverado Z71 Crew Cab ~ '15 Challenger R/T Scat Pack 392 ~ '11 Escalade ESV ~ '71 Cheyenne swb ~ '66 Country Sedan ~'50 3100 bagged ~ '80 Wife ~ Late model kids

LEEVON is offline   Reply With Quote
Old 10-05-2011, 12:49 AM   #59
73CheyenneSuper20
Registered User
 
73CheyenneSuper20's Avatar
 
Join Date: Nov 2008
Location: San Bernardino, CA
Posts: 92
Re: what are you guys getting for mpg?

My DIC is reading an overall average of 11.5mpg's...
2008 6.0, 4 speed trans (4L70E), 3.73 gears, 4x4, 5'9" bed, extended cab, 20" aluminum rims, 35x12.50 Toyo's, Cat-back Magna Flow exhaust 1 into 2 duals out the back, some air intake like K&N, and a Hypertech programmer, 85k miles.

I didn't do any of this stuff, I bought it like this in Jan with just under 76k on it. I haven't did the mpg's on paper, but roughly from fillup to fillup it's about right (fillup with about 20 gallons, went about 220 miles, etc)

The Hypertech re-adjusts for the tire size and corrects the speedometer... I think I'm gonna plug it in and see what it says about the program it's running...
__________________
'71 C25 Camper Special, 402, TH400, Longbed, Power Loc axle, Figuring out the rest of the details....
'10 Dodge Charger SXT - DD
'91 Kasel M101A2 3/4 ton trailer (It has Chevy rims!)
73CheyenneSuper20 is offline   Reply With Quote
Old 10-08-2011, 05:56 PM   #60
willinwtx
Registered User
 
Join Date: Sep 2011
Location: san angelo,tx
Posts: 14
Re: what are you guys getting for mpg?

my 2011 rclb with the 5.3 and 6 speed and 3.42 averages 15.5-16 has 20k on it. it's an oil field truck and 70 percent of my driving is dirt road under 40 mph. my 08 with the v6 and 3.73's averaged 14 the entire 175000 miles i had it.
willinwtx is offline   Reply With Quote
Old 12-05-2011, 01:34 AM   #61
Bad70sbchevy
Registered User
 
Bad70sbchevy's Avatar
 
Join Date: Aug 2009
Location: Newberry,FL
Posts: 269
Re: what are you guys getting for mpg?

My 2010 Silverado 4.3V6 with 3.23 gears gets 18.5mpg mixed between rush hour traffic and highway, I ain't complaining.

BTW if you really want better gas mileage you would have to run leaner fuel ratios (that the engine would allow), but you can't pass emissions. I'd have to disagree with carbs getting worse fuel mileage than FI due to them generating a larger dropplet. If tuned right ideally, a carb could achieve the same fuel mileage, but with EFI it is much easier to tailor an ideal fuel curve than a carb and you can get feedback from O2 sensor.
__________________
1970 Chevrolet C-10 w/355sbc
2010 Silverado Daily Driver
1971 Mercedes 280sl project car
Bad70sbchevy is offline   Reply With Quote
Old 12-16-2011, 11:42 AM   #62
OLDIRON69
Registered User
 
Join Date: Mar 2007
Location: Ben Wheeler,Texas
Posts: 992
Re: what are you guys getting for mpg?

05, 2500HD 6.0 4.10 gears, last 7.5 hour road trip at speeds of 75-85 I actually got 12.5 mpg! I have never babied the truck and it has 175K miles. The best I got ever was 16 hwy doing 65 the entire way on a very flat road witht he cruise set. When I replace it I plan on a custom tune.
__________________
05 2500HD 6.0 excab
69 LWB-Gone but not forgotten!
68 Dodge Charger 383/727
69 Dodge Charger-440/4spd
OLDIRON69 is offline   Reply With Quote
Old 12-16-2011, 12:36 PM   #63
tonyscustomrides
Registered User
 
Join Date: Sep 2009
Location: Ferndale, WA
Posts: 36
Re: what are you guys getting for mpg?

i bought a 2011 gmc sierra, rcsb, 2wd, 5.3 AFM Flex Fuel,6 sp, 3.42, all stock and im gettin 22mpg averaging 50mph (back roads). This is no lie, i barely believe it myself. I havent driven it on the highway much, ive had it for two months and just rolled over 1500 miles.
__________________
77 chevy k10 Bonanza-Restored when i was 17
76 chevy c10 short box-scrapped
81 chevy c10 silverado short box-project
64 impala 2 dr hard top-project waiting to get started
tonyscustomrides is offline   Reply With Quote
Old 01-02-2012, 10:45 PM   #64
Chrislidgett
Registered User
 
Join Date: Jan 2012
Location: Omaha Nebraska
Posts: 38
Re: what are you guys getting for mpg?

I just hit 10000 miles on my 11 crew 4x4 I had fast motorsports tune it with 600 miles on it and I average 17.2 mpg back and forth to work hwy/city mix on the 3 hr trip to my parents house I will get about 21
Posted via Mobile Device
Chrislidgett is offline   Reply With Quote
Old 01-09-2012, 02:35 PM   #65
stroker87
Registered User
 
Join Date: Nov 2011
Location: Chicago, IL
Posts: 319
Re: what are you guys getting for mpg?

Quote:
Originally Posted by drew86 View Post
I think there is something to be said in the difference in weight of wheel and tire combos also.I even experienced a slight loss in mpg's going from factory 17's to factory 20's.I also had a set of 20x10 kmc's with 305/50's for about 3 years on my 07,and they were definitely the worst.I thought they would be better with the taller tire.My truck is 2wd with the 5.3 and 3.73 gear.Averaged 13.5 with the kmc's,15.2 with factory 20's,and 16 with the 17's.
+1

truck with rims lager then 17" will get lower MPG, my 07 suburban with the stock 17's on the Hwy gets 18.5mpg running 70/75mph with my 22" rims same speeds same trip (Chicago to Cleveland) only get 16mpg, mix city/hwy avg 12.5mpg but i have a heavy foot and any time i'm on the e-way i'm driving over 80mph

now I have a programer that I put in economy when taking a trip and can get 17.5mpg with my 22" wheels but it really kills the performance of the suburban and makes it feel like a V6

as for the AFM its a joke only time it gos in to v4 is down hill or when i lift my foot off the go peddle to stop
stroker87 is offline   Reply With Quote
Old 01-09-2012, 02:50 PM   #66
piecesparts
Parts and more parts
 
piecesparts's Avatar
 
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,829
Re: what are you guys getting for mpg?

It is not the fact that the rims are larger in diameter. It is the taller tire and the affect that it has on the RPMS and the power needed to make it move. If you go 20" rims, but the tire is approximately the same diameter,then the RPMS will be the same and the MPG will be the same. I am getting decent mileage with my 265/50/20 tires on my new truck, just because it works well with my gear ratio. Plan your change and align gears and tires effectively.
__________________
Frank
piecesparts is offline   Reply With Quote
Old 01-09-2012, 03:30 PM   #67
stroker87
Registered User
 
Join Date: Nov 2011
Location: Chicago, IL
Posts: 319
Re: what are you guys getting for mpg?

Quote:
Originally Posted by piecesparts View Post
It is not the fact that the rims are larger in diameter.
your right its the WEIGHT difference pick up a stock 17" wheel then a 22" wheel you'll see what i'm talking about I've had a few set of rims (8 and counting) on my suburban and most was the same over all tire height so the speedometer would ready correctly but the weight of the bigger or even just a different wheel that weights more in the same size is what kills mpg

my stock tire size is 265/70/17= 31.7 Overall Diameter

my aftermarket wheels have 305/40/22= 31.6 Overall Diameter but weight a lot more then the stock rim/tire combo so mpg suffers

the more they weight the more power it takes to turn them even if they are the same size

if you typed your current tire size correctly you should be getting better MPG that size 265/50/20 is a 30.6 Overall Diameter witch is smaller then the stock 20 inch size that is 275/55/20 and that is a 31.8 Overall Diameter tire

Last edited by stroker87; 01-09-2012 at 03:37 PM.
stroker87 is offline   Reply With Quote
Old 01-09-2012, 09:55 PM   #68
piecesparts
Parts and more parts
 
piecesparts's Avatar
 
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,829
Re: what are you guys getting for mpg?

Quote:
Originally Posted by stroker87 View Post
your right its the WEIGHT difference pick up a stock 17" wheel then a 22" wheel you'll see what i'm talking about I've had a few set of rims (8 and counting) on my suburban and most was the same over all tire height so the speedometer would ready correctly but the weight of the bigger or even just a different wheel that weights more in the same size is what kills mpg

my stock tire size is 265/70/17= 31.7 Overall Diameter

my aftermarket wheels have 305/40/22= 31.6 Overall Diameter but weight a lot more then the stock rim/tire combo so mpg suffers

the more they weight the more power it takes to turn them even if they are the same size

if you typed your current tire size correctly you should be getting better MPG that size 265/50/20 is a 30.6 Overall Diameter witch is smaller then the stock 20 inch size that is 275/55/20 and that is a 31.8 Overall Diameter tire
Remember the wheel and tire are rolling weight and so with that in mind, there is only a small portion of it that is actully suspended and adding weight to the vehicle. It is not the weight that you are dealing with as much as it is the circumference that you have to get the wheel to turn effectively to make it work. Turning a small gear is easier than turning a larger gear with the same output ratio from the tranny. That is why drag racers go for the different lower gears for different length tracks

You are right, my tire diameter is smaller than the monsters that were on the truck when it was stock. That smaller diameter along with my 3.42 gearing makes the application of torque to the ground much easier, since the smaller diameter essentially changes the gear ratio to a lower gear.
__________________
Frank
piecesparts is offline   Reply With Quote
Old 01-09-2012, 11:48 PM   #69
stroker87
Registered User
 
Join Date: Nov 2011
Location: Chicago, IL
Posts: 319
Re: what are you guys getting for mpg?

Quote:
Originally Posted by piecesparts View Post
Remember the wheel and tire are rolling weight and so with that in mind, there is only a small portion of it that is actully suspended and adding weight to the vehicle. It is not the weight that you are dealing with as much as it is the circumference that you have to get the wheel to turn effectively to make it work.
if that was true why is it that with my 22" rims witch is just a touch smaller Overall Diameter then my stock 17" rims I loose 2.5mpg??

driving the same trip cruise set at the same speeds??? I run from Chicago IL. to Cleavland OH. on business a lot I have made the run many times on my stock rims and on my big rims with my stock rims I get about 65 mile more to a tank

Sorry for the hijack, every one
stroker87 is offline   Reply With Quote
Old 01-10-2012, 03:49 PM   #70
maxh
Registered User
 
maxh's Avatar
 
Join Date: Sep 2009
Location: Lethbridge, Alberta
Posts: 174
Re: what are you guys getting for mpg?

Well my 07 nnbs cc 2wd did wicked this past weekend. Driving flat with cruise set I got 26mpg at 145k or 90mph in 4 cyl mode. Kickin it to V8 I was getting atleast 22mpg at that speed.
__________________
Instagram @maxh15
#maxhtrucks
maxh is offline   Reply With Quote
Old 01-10-2012, 09:58 PM   #71
piecesparts
Parts and more parts
 
piecesparts's Avatar
 
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,829
Re: what are you guys getting for mpg?

Quote:
Originally Posted by stroker87 View Post
if that was true why is it that with my 22" rims witch is just a touch smaller Overall Diameter then my stock 17" rims I loose 2.5mpg??

driving the same trip cruise set at the same speeds??? I run from Chicago IL. to Cleavland OH. on business a lot I have made the run many times on my stock rims and on my big rims with my stock rims I get about 65 mile more to a tank

Sorry for the hijack, every one
What is your gear ratio, tranny type, and what are the two different tire sizes that you are running? If you put your engine at a point where it is now running at an RPM that is just out of the band on the opposite end, it works the other way.
__________________
Frank
piecesparts is offline   Reply With Quote
Old 01-16-2012, 02:36 AM   #72
Bad70sbchevy
Registered User
 
Bad70sbchevy's Avatar
 
Join Date: Aug 2009
Location: Newberry,FL
Posts: 269
Re: what are you guys getting for mpg?

Quote:
Originally Posted by stroker87 View Post
if that was true why is it that with my 22" rims witch is just a touch smaller Overall Diameter then my stock 17" rims I loose 2.5mpg??

driving the same trip cruise set at the same speeds??? I run from Chicago IL. to Cleavland OH. on business a lot I have made the run many times on my stock rims and on my big rims with my stock rims I get about 65 mile more to a tank

Sorry for the hijack, every one
It's probably resulting from a higher rotating mass from the 22" wheels. It takes more power to turn a heavier tire than a lighter one. Either that or a smaller OD is causing the motor to turn more rpms at 65 which can also cause a dip in mpg depending on how much of a difference in OD.
__________________
1970 Chevrolet C-10 w/355sbc
2010 Silverado Daily Driver
1971 Mercedes 280sl project car
Bad70sbchevy is offline   Reply With Quote
Old 01-17-2012, 02:22 PM   #73
FMBL
Registered User
 
FMBL's Avatar
 
Join Date: Jan 2010
Location: NRH, TX
Posts: 198
Re: what are you guys getting for mpg?

07 yukon 5.3 auto 3.42's with 305/45-22 seems to get 12.5-14.5 city, hwy or combined.
__________________
78 El camino
89 GMC SWB
98 Z28
99 2dr 2wd Tahoe (sold 8/31/2012)
07 Yukon SLT
09 G8 GT
FMBL is offline   Reply With Quote
Old 01-18-2012, 09:37 AM   #74
swb85
On a budget like Fred Sanford
 
swb85's Avatar
 
Join Date: Oct 2005
Location: Topeka, KS
Posts: 2,030
Re: what are you guys getting for mpg?

Even with identical overall tire diameters, heavier rims (ie, higher mass) will absolutely hurt fuel economy, along with acceleration and braking. Look up Newton's law of motion if you're having trouble wrapping your head around it.
__________________
'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
swb85 is offline   Reply With Quote
Old 02-25-2012, 07:42 AM   #75
cadpwrd
Registered User
 
cadpwrd's Avatar
 
Join Date: Oct 2008
Location: Fredonia NY
Posts: 65
Re: what are you guys getting for mpg?

Last weekend I took a trip to Canton, OH (with a pitstop at Summit Racing in Tallmadge). It was about a 3 hour drive from where I live in western NY. My 2wd RCSB with the 4.3 averaged 19.6mpg with the cruise set at 73mph. That's the best Ive seen on the highway. I usually average 13/14 mpg around town and 17/18 on the highway.
__________________
'86 C-10 Shorty-500 cu in Cadillac powered project truck
'13 Silverado ext cab Z-71 lowered 2/4
cadpwrd is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 01:27 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com