Anyone ever chipped or tuned their 8.1's for better economy? I've got all the power I need but looking for mileage. No, I'm not complaining about getting 7-8mpg towing, just wondering if there's help out there.

My buddy put 285's on his and the mileage went to hell so he chipped it and it brought it back to normal. I guess it would help even more if he wouldn't have put the bigger rubber on it.

get a nelson's tune, or a westers tune. they are far beter than any hand held programmer.

when the milage "went to hell" after puting on 285s...did he correct for the 7% or so loss in mileage simply due to less rotations per mile of the tire when increasing in size? Also, when he "chipped it" and mileage increased....was that simply cause of reprogramming for 285s? I'd imagine so. If not....I'm gonna "chip it" cause I'd love more mpg.

I did the same thing....except corrected for the increase in tire diameter mathamatically. I did not notice any measureable difference in mileage from before or after increased tire size. I think the 8.1L has so much torque that it really doesnt take much more fuel to get/keep her going. Barelly felt the difference even driving but I usually drive conservatively and pretty much idle from a stop light to get going otherwise it spins the tires or starts to abruptly when gassed (I hate Electronic Throttle Control ETC!).

With the numbers he still lost about 2mpg.

With the numbers he still lost about 2mpg.

What did he do to fix it??

I have the westers tune in mine with free flowing exhaust and intake mod. When I did the tune I said that I didn't care about milage give me the power and I will tell you what this thing is awesone. It will cook the rear wheels from 0-80 on the gravel roads" don't want to do it on the tar might hurt the drive line" the thing sounds like a stock car and feels like one to. Milage was the exact same b-4 and after the tune. If you think about it a 2.5L car will get 30mpg if you were to drive 3 of them your milage would be 10. Just remember the 8.1 has a lot of cubes and one hell of a lot of pulling power. If you want the milage do as I did but a $200 pile of junk for back and forth to work and leave the HORSE in the shed.

If you think about the mileage issue you just can't get your money back from any of the supposed upgrades. Your truck has a given weight and you have to expend a given amount of power to move it. This is why you don't see any real difference in mileage for the 8.1 and 6.0 gasser. I think the main difference in the diesel mileage is due to the fact that the fuel has more btu's per gallon rather than the engine technology. A polished and balanced engine will have less operating loss but would not live long enough to get the cost back from fuel savings.
The various tunes available can meet special requirements or desires for specific situations but they will be lacking in other areas as a result. The factory tune is designed to best meet all round use on regular fuel without overheating under load.

im with him thoes chips for gassers cant make much of a difference for mileage if they do anything at all, they are giving you more fuel so how is the better mileage gonna work?

Thanks for the replies, I was a bit skeptical about the tunes and chips but a neighbor was trying to tell me how good they are. I do have a run-around car as SUPER-H mentioned, 1990 buick with 180,000 miles and I'm concerned that it may be on it's last oil change! Trying to decide if I look for another beater or get the truck out of the garage!

I've owned 3-8.1L's and one 6.0-w/4:10's. The 01 8.1-4:10's was in a burb and it got 11 no matter what. The 03-8.1-4:10's in a burb also gets 11-12 no matter what. The 6.0 was in a ext-cab pick-up and it got 12-13 no matter what. I just bought a new 06-8.1L-crew cab pick-up-ally-3.73's, and the little computer said it got 14.5 on the way home from the dealer, about a 4hr ride with 2-3 long traffic delays creeping for about 40 minutes. don't know how accurate it is, but i'll find out on the next full tank. either way you look at it, it's kinda silly to have a 6.0 when the 8.1 does near the same, if not better in the new ones? of course the new 6.0's w/DOD and VVT should do better but they'r just coming out, so we'll see on those too. Wish the 8.1 was offered in the new 07-HD's with DOD and VVT, but we all know the 8.1 has been discontinued and why i just bought a 8.1 classic. Can't wait for gm to potentially/hypothetically get us an 8.1 replacement.

we all know the 8.1 has been discontinued and why i just bought a 8.1 classic. Can't wait for gm to potentially/hypothetically get us an 8.1 replacement.

The 8.1 hasn't been discontinued, it just won't be offered in the pickups anymore. The Kodiak and TopKick will still get the 8.1 option, and the Marine (Mercruiser/Mercury Marine) still gets the 8.1.

I have the Predator programmer with the 87 octane tune uploaded into my Avalanche. On a 4,500 mile trip from Houston to Raleigh and back it averaged 13.9 MPG (hand calculated). 3.73:1 gearing. The best MPG that the DIC read was 14.5 around 69-72 MPH with the cruise on for one long stretch of interstate.

One thing that a tuner (at least the Diablo Predator) will do is allow you to change transmission parameters, such as shift firmness. Stock mine shifted like a Lincoln Town Car unless in Tow-Haul mode. I firmed the shifts and removed the 98 MPH speed limiter. Can't say much about the power. Feels pretty much the same with the premium fuel tune as it does plain stock. One thing I would like to do that you can't do with the tuners is totally eliminate Torque Management. Mine won't spin the tires on pavement unless it's wet. WIth over 400 Ft Lbs of big-block torque, you'd think it would SMOKE them like an old musclecar. It would if not for TM!

I owned a 02 8.1 averaged 11 all day with or without a hypertech. Don't waste your money with a hand held IMHO.

One thing that a tuner (at least the Diablo Predator) will do is allow you to change transmission parameters, such as shift firmness. Stock mine shifted like a Lincoln Town Car unless in Tow-Haul mode. I firmed the shifts and removed the 98 MPH speed limiter. Can't say much about the power. Feels pretty much the same with the premium fuel tune as it does plain stock. eliminate Torque Management. Mine won't spin the tires on pavement unless it's wet. WIth over 400 Ft Lbs of big-block torque, you'd think it would SMOKE them like an old musclecar. It would if not for TM!

With just the 4L85E,it may not be a good idea to remove all of the torque management. I think the 6.0 engine can have it all removed,but the 8100 should be held back a little unless its in front of an allison.

8.1 eith have an allison of a 6 speed manual unless they are in a surburban. There is no 4l85 behind them unless they are in a burb or a 2000 3500HD cab and chassis

8.1 eith have an allison of a 6 speed manual unless they are in a surburban. There is no 4l85 behind them unless they are in a burb or a 2000 3500HD cab and chassis

Look in his avator and signature, hes got an Avalanche.They have the smaller trans 4L85E.:o: