06-07.5 LBZ & LLY Duramax PowertrainDiscussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect
how many rpms does your truck revs going 65 mph and how many mpg do you get at that speed. im trying to find my sweet fuel economy spot but it seems that the faster i go the better it gets, the slower i go the shittier it becomes. at 65 mph my truck revs at 1500 rpms and roughly gets around 14.5 to 15 mpg. my friend has a 05 lly and it revs 2200 rpms at 65 and he gets 20 mpg, although its a 2wd on stock 265 tires. i thought at first that it seems a little high going 65 and it should consume more fuel at that rpm. so if i was revving my engine at 2200 rpm would my MPG increase or decrease? i have been trying to find my peak torque rpm where it will maintain optimum fuel economy.
__________________ 2006 Chevy Silverado 2500HD crew cab with a LLY 6 speed Allison 1000
6" RCD suspension lift rollin' on 20' Driv wheels and 325 nittos
4" Silverline cat back exhaust (want to rid of it for a turboback 5")
Engine all stock for now
I don't know about 65 but @ 70 my lb7 is @ 2000 rpm's and I have been averaging 21 mpg on the highway. I am running completely stock even down to the tires...until this spring!
__________________ 02 Chevy 2500 LB7 CC LB 6 speed manual 64k miles 4X4 brushguard, toolbox, Husky floor liners
someday: 5" TB exhaust, Edge Juice w/ attitude, 4" lift, Fass fuel system(try to save my injectors), south bend clutch
95 ranger ex-cab 2wd 60k...part time truck
02 explorer 4.0 AWD 85k...wifes ride
i get better fuel economy running 1700-1800RPMS then at 1500-1600RPM's on our LBZ..
__________________ James
TyreBoyz Pulling Team
Pulling Truck called Late Nights.05 LLY 3500 EC LB DRW tuned By Idaho Rob.
Work truck,06 LBZ 2500 CC SB SRW,tuned by Idaho Rob and PPE at times
My Truck now,1987 Chevy 2500 350 tweaked,6" SuperLift,350 V8 bored 60 over,Elderbrock headers Cam and Titanium Rockers,750 Twin Pumped Holley Carb and some other goodies.crank dynos over 400HP.
I believe I'm sitting at about 1800 rpms at 70mph.
I also get slightly better mpg at 70 than I do at 55,60, or 65.
After 70 things start to tail off though.
__________________ 2007 LBZ 2500HD CC SB 4x4 Red
Leer canopy, Aries Oval step bars, 18" AR Cannons wrapped with General Grabber HTS 275/65R18's, everything else stock.
Love this truck....HATE the fuel economy yea yea, I know it's a truck, and YES I want the same mpg as a Civic
i get about 18 mpg at 60 mph, 20-21 mpg at 68 mph. sorry i have not paid enough attention to the rpms to remember what they were. but we are fairly close on tire sizes so you might be about the same.
__________________ '05 2500hd cc sb 4x4
duramax 6.6turbo/allison
265's (had to get rid of them 315's)
front keyed and leveled
b&w hitch and 5th wheel conversion
5% window tint, gm nerf bars
Stock 4 now; new exhaust and tuner soon,
tranny upgrade when I gots the monies!!!
thats interesting. at 75 mph i get better fuel economy too.70 is not too bad but anything under 66 mph it becomes crappy. at 75 its around 1700 rpm i believe. its going to be hard for me to keep it at 75 on the highway most of the time because where i drive,they put a shitload of photo enforcement all over the highway which is absolutely ridiculous! if you go 10 mph over the speed limit it will flash you and send you a hefty fine through the mail.
__________________ 2006 Chevy Silverado 2500HD crew cab with a LLY 6 speed Allison 1000
6" RCD suspension lift rollin' on 20' Driv wheels and 325 nittos
4" Silverline cat back exhaust (want to rid of it for a turboback 5")
Engine all stock for now
i get about 18 mpg at 60 mph, 20-21 mpg at 68 mph. sorry i have not paid enough attention to the rpms to remember what they were. but we are fairly close on tire sizes so you might be about the same.
you say you get around 20 mpg, theres gotta be something wrong wit mine since i usually get around 15 most of the time. but you have a 5 speed and i have a 6 speed tranny, arent 6speed tranny supposed to get better fuel economy? did you have your speedo recalibrated or any tuner on it? my speedo is pretty much off by 10 mph or more as i go faster than 70. so im pretty sure my miles are off by a few miles when i hand calculate my mpg.
__________________ 2006 Chevy Silverado 2500HD crew cab with a LLY 6 speed Allison 1000
6" RCD suspension lift rollin' on 20' Driv wheels and 325 nittos
4" Silverline cat back exhaust (want to rid of it for a turboback 5")
Engine all stock for now
What if you put it in manual mode and only ran it in fifth gear to get the rpms up alittle? I do not know if it would be too high ( I have a 5speed), might be worth a try. Mine gets 20mpg at 70mph 2200 rpms.
yea i was thinking put it in manual and run it in 5th gear for low speeds around 55 to 65 then 6th gear over 65 mph. my friend at my work claims that the dealership told him that he has a 6 speed tranny in his 05 and tells me his revs at 2200 at 70. i kept telling him he has a 5 speed cuz a 6 speed drops about 300 rpms lower than 5 speed does at highway speed.
__________________ 2006 Chevy Silverado 2500HD crew cab with a LLY 6 speed Allison 1000
6" RCD suspension lift rollin' on 20' Driv wheels and 325 nittos
4" Silverline cat back exhaust (want to rid of it for a turboback 5")
Engine all stock for now
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and it should consume more fuel at that rpm. so if i was revving my engine at 2200 rpm would my MPG increase or decrease? i have been trying to find my peak torque rpm where it will maintain optimum fuel economy.
yea yea, I know it's a truck, and YES I want the same mpg as a Civic 
Linear Mode
