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Finally got a new tow rig! (any other 8.1 owners out there?)

Old 10-06-2014, 09:42 AM
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Originally Posted by ICDEDPPL
Anyone Ive ever talked to pretty much says the same thing 10mpg no matter what , my experience is the same except for towing (6mpg) how you ^^^ get 16-18mpg is beyond me.
Blackbear performance tuned my truck, AFR`s are 13.5 cruise, 13.1 acceleration. Ive had long discussions (btw, you`ll never get him on the phone communication is email only)he keeps blaming parts. Ive replaced a few , (MAF, both 0`2s) now he sais its the coolant sensor or its burning oil. (doesn`t use any oil).

Damn Ive just reminded myself how much I can`t stand this truck, I gotta stop thinking about it or I`ll be on the web searching for a Diesel again.

Good luck with yours thou , as long as you don`t have an 80`s heavy resin bucket it should tow just fine
You REALLY have to pay attention to get that mileage. Cruise control gets a lot worse than manual petal control. There is a tiny sweet spot,i mean tiny. Using the dash MPG readout you can find it (yes I know math and do calculate old fashioned way). I didn't do an off the shelf tune. I also keep the fuel enrichment OFF below 3000 rpm, I sacrificed a little extra power below that, but helped mileage a bunch and had more than enough anyways. Best 50% (70 mph)hwy/50% (60 mph) off highway average I ever had was 13.1 mpg. Got 14.3 once on a long trip west across Michigan but that was all 60 mph non highway which is the sweet spot for this thing. That was truly driving like a grandpa. On any given day, my average is 10-11 because my truck isn't a daily driver and I do flog on it frequently, otherwise why have a BBC in a truck?

Im just saying, much better than stock mileage is possible, but I only pay attention on long trips because this is usually only time I ever fill the 40 gallon tank.

I did have a Quadzilla programmer in the truck before my HP tuners, but I had no mileage gain from that since it raised all my shift points and had full fuel enrichment settings. Also the shift points were so close to the rev limiter, it would bounce off the rev limiter instead of shifting at WOT. Pain in azz.

Last edited by Gimme Fuel; 10-06-2014 at 09:44 AM.
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Old 10-06-2014, 09:43 AM
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Originally Posted by Rookie
When I was out test driving 8.1 Avalanches (7 of them) not one of them was above 9 mpg ave on the dash history. And those usually lie on the high side. Seemed to be a great engine though.
Yea, in stock form, they sucked! didn't even feel like it had any more power than a 5.3 half ton when I bought mine.
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Old 10-06-2014, 11:14 AM
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GM may have not made the burbans in a d-max.....but its an easy swap from all i have read up on it. I was seriously looking for a 2500 burban before i came across my 2010 avalanche and the price was something i couldn't pass up.......but the 2500 burban with the 6.0 or 8.1 will take the d-max engine...its "mostly" plug and play.....depending on the truck you need to swap over the 4WD switch assembly, the power adjust pedals if the truck has them.....the diesel dash cluster (adding one extra wire back there) and some mods to the fuel pump. The Body will need a progressive body lift starting with a 2" spacer and gradually going to 0" at the back. If you search the forums online for "frankenburb" you will find a forum discussing the whole thing.
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Old 10-06-2014, 03:57 PM
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I put over 100K miles on an 01 CC Long bed w 8.1

10 MPG Period- one QT oil every 1200 Miles Period.
I check mileage almost religiously at fill ups- Put in 24 Gal - I went almost 240 miles Towing about 8 mpg

Now in the business fleet I have an 02 3500 Van- same motor- Same mileage- same oil usage
VERY strong motors!!
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Old 10-06-2014, 05:07 PM
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I have a 04 dually. I towed my straight bottom top gun and now my TS Playboy Cig. The truck tows great, it has 95k on it. I pretty much only use it for towing. It gets 7-8 towing. It gets 10-11 everyday driving. The Allison transmission makes this a great truck. Uses the typical quart of oil every 1500 miles while towing.
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Old 10-06-2014, 06:12 PM
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My older truck is a gas job 2500. Its a great truck that works hard and gets the job done but i get there quicker and with less fuel with my Duramax. I have no problem yanking my boat around with either one though.
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Old 10-06-2014, 07:24 PM
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Had an 02 dually. Loved the 8.1 and Allison but whenever you wanted to go somewhere your first stop was for gas. As previously stated 10 mpg. empty or loaded. Best was 300 miles on 32 gals. at or below speed limits towing a 26' velocity. Most performance mods just make you mash your foot down cuz it's fun so increased mpg. goes out the tailpipe.
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Old 10-06-2014, 07:38 PM
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Love the 8.1 2500 suburbans! I'm in my second one now, it's an '06. I had an '02 w/4.10 gears it towed a little better and would probably out run the one I have now, it has 3.73's. I get about 1-2mpg better with the '06. I bought this '06 with 22,000 it now has 117,000 on it been great to me. The dash says 10.4mpg avg. for the life of vehicle. I have figured it myself several times,11-12 on the hwy., around town driving kills the mileage. Every big block I have ever owned in a truck has gotten 10mpg, loaded or not, driving like a grandpa or like a stole it, doesn't matter, 10mpg give or take that's what you get. They are the best gas motor out there for towing.

Mine is stock. The info on the tune and mods is great. Ive been thinking about doing some things to it now that it's out of warranty.
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Old 10-06-2014, 08:02 PM
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I have 02 chevy crew dually 8.1, 5 speed Allison,4.10 gears..... Internet mileage is sometimes suspect .Yesterday I drove 130 miles to pick up a small boat (26' searay).Going there I went on some two lane rds and roughly half expressway .I usually drive as fast as reasonable to get somewhere. But I will run less than ten mph over posted speed limit, on cruise .So I was going 64 - 78 mph.Truck got over 11 mpg .Coming back with that little boat on cruise ,I stayed on interstate only (no two lane) running about 76-78. I got 6.8 mpg.Truck runs great .That is real world mileage, running with traffic...not holding back traffic
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Old 10-06-2014, 08:06 PM
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Yeah I`m starting to consider it.. like GIMME FUEL says fuel enrichment and other factors could make this perform a bit better. Hope n iggaBear performance didn`t lock my pcm.

Last edited by ICDEDPPL; 10-06-2014 at 08:37 PM.
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