06 8.1L Vortec Tuning

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,517
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Central OH
Interesting. My Mitchell Works repair info only shows an allusion. Wonder if there is an error there.

That's all I've read, is that only Allison came behind them. I saw this truck in person back in the day, but maybe it was a factory screw up? Only one I've seen equipped like that
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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Well I'll have to disagree with that. Dad looked at a brand new 3500 dually back in 04-05, had the "hd" 4 speed option

The left hand side said HD 4 speed, but the right side add on options column would have listed the allison trans. Pickups with the 8.1l all got the ALLISON. Suburban's and Avalanches got the 4l85e behind them.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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I thought they were 500ft-lbs, my error. Looks like they were 330-345hp/440-455ft-lbs.


LB7 was 235-300hp/500-520ft-lbs
LLY was 310hp/520 ft-lbs




Above numbers are according to duramax hub.

Those numbers are off. The LB7 was always 300hp. The torque was listed at 520 ft lbs, but all the tune files I have looked at all had the max torque figured at 550. And the LLY was 305/600 for 04, and 310/605 for 05. Not sure on 4500/5500 power numbers, just pickups.
 

zakkb787

<that’s not me...
Sep 29, 2014
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Those numbers are off. The LB7 was always 300hp. The torque was listed at 520 ft lbs, but all the tune files I have looked at all had the max torque figured at 550. And the LLY was 305/600 for 04, and 310/605 for 05. Not sure on 4500/5500 power numbers, just pickups.

Thanks for those number Ferm. Dmax hub numbers always confused me.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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I know the Yaks are not 300hp. I don't remember If its 285 or 295. But I know the vans were at 270.

Vans were 250/460 derated for the 4l85e. And the kodiak with a 6.6l from everything I could find was 300hp. I even found a 2003 & 2004 press release that quoted 300/520 for the 4500/5500 trucks. And the 06 kodiaks got the 310hp tune, but it never went above this until the latest 2019 at 350hp.
 

duramaxnate

Professional Amateur
Feb 18, 2014
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Vans were 250/460 derated for the 4l85e. And the kodiak with a 6.6l from everything I could find was 300hp. I even found a 2003 & 2004 press release that quoted 300/520 for the 4500/5500 trucks. And the 06 kodiaks got the 310hp tune, but it never went above this until the latest 2019 at 350hp.[/QUOT

I don't remember where I saw the HP #s for the yaks but I don't know where those numbers came from in the first place. So they probably could be wrong. :roflmao:
 

1970SS8.1L

New member
Mar 28, 2019
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I have an 06 8.1 with Allison 6 and 4:10 gears. Stock I got 14mpg highway unloaded. 6 mpg with 12,500lbs. After a cold air intake, ram air hood, mufflers, and tune I was getting 16mpg unloaded highway and got 9.5 mpg with 12,500lbs. Now I did a cam, roller rockers, modified intake, 90mm throttle body and am in the process of tuning it right now. After the cam swap before tuning I was getting 8mpg unloaded. I’ve gotten it back up to 12mpg so far. Have not towed with it yet, still doing the Allison relearn. Each change I made has added a lot of power. These 8.1’s are reliable beasts. I have driven all over the western USA blowing past diesels up steep grades in the fast lane at 80 in cruise control with 12,500lbs. I do stop for gas a lot, but it’s fun to blow past the same diesels again after the re-fuel. I can’t wait to tow with this thing now. I am bias to the 8.1 though if you know what it truly is nothing compares. It is the only motor to ever pass the marine dock test and is all industrial. I have heard of some 8.1s going over 600k before a re-ring job. I also have one in my chevelle with a t56.
 

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1FastBrick

Well-known member
Dec 1, 2016
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Trying to compare a gasser running on E and gasoline for mileage is like trying to compare propane vs hydrogen. E is always way lower, but so is the cost.... And you don't see much gains on E unless it's boosted.

Who's comparing? I am just reporting the difference for the specific modification.

I don't see the value for the cost and I personally don't waste my time with E85.

The owner happens to like the way it pulls with E85 especially on the hills.

Just so happens his 03 is running on an 06 operating system on the ECU side.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,761
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I have an 06 8.1 with Allison 6 and 4:10 gears. Stock I got 14mpg highway unloaded. 6 mpg with 12,500lbs. After a cold air intake, ram air hood, mufflers, and tune I was getting 16mpg unloaded highway and got 9.5 mpg with 12,500lbs. Now I did a cam, roller rockers, modified intake, 90mm throttle body and am in the process of tuning it right now. After the cam swap before tuning I was getting 8mpg unloaded. I’ve gotten it back up to 12mpg so far. Have not towed with it yet, still doing the Allison relearn. Each change I made has added a lot of power. These 8.1’s are reliable beasts. I have driven all over the western USA blowing past diesels up steep grades in the fast lane at 80 in cruise control with 12,500lbs. I do stop for gas a lot, but it’s fun to blow past the same diesels again after the re-fuel. I can’t wait to tow with this thing now. I am bias to the 8.1 though if you know what it truly is nothing compares. It is the only motor to ever pass the marine dock test and is all industrial. I have heard of some 8.1s going over 600k before a re-ring job. I also have one in my chevelle with a t56.


that moment you scower the internet looking for a post anywhere besides the 8.1 forum to post in and you find it! :baby: :roflmao: :roflmao:
 

Columbus450

Member
Aug 24, 2017
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Louisiana
He actually thinks his 8.1 Can get around a diesel lol thanks for the laugh today that was hilarious


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matthew86

Member
Mar 16, 2018
55
2
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Eastern WA
Wow. I have a 99 Chevy 3/4 with the 6.0 gasser and 4.10s. I got maybe 15mpg totally stock, 12 after the S/C and 35s highway empty, and 3.5-8mpg depending which trailer I hooked to it and what mess I towed through. Last trek across Montana in a blizzard netting 3.5mpg and less than 80 miles to a tank, I bought a duramax. Lol. Those numbers are pretty impressive for a 8.1 comparatively. My LBZ under the same trailer empty has gotten 12-14ish. 10-10.5 under my flatbed with varied loads (8500k empty) and lowest of about 9 grossing 25k. But comparing the two trucks pulling loads wasn’t even fair in my case. Does the 8.1 really do that much better than the 6.0?

Edit: my enclosed trailer on that Montana trip weighed 6500lb empty, about 12k loaded.


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duramaxnate

Professional Amateur
Feb 18, 2014
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I had a L18 Yukon XL in HS, I towed with it quite often. Had a kenne bell blower, a tune obviously and I think a small cam don't remember...anyway. Got 14-15 highway unloaded, around town, I wish. Towing? I defiantly wish, BUT it defiantly did better than my dads old 6.0 gas truck, wasn't passing trucks on grades but keeping up without an issue BUT if I was lucky, which I wasn't most of the time (partly why I don't gamble...lol) I would be able to measure in Miles per gallon instead of Gallons per mile. :roflmao:

I have a soft spot for those iron dinosaurs, But nothing compares to a Diesel's towing ability.

Although, They do pretty well in the Kodiaks and the Workhorse W series Chassis and was a good alternative to the duramax back in the day.
 
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NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,224
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At Da Beach
Wow. I have a 99 Chevy 3/4 with the 6.0 gasser and 4.10s. I got maybe 15mpg totally stock, 12 after the S/C and 35s highway empty, and 3.5-8mpg depending which trailer I hooked to it and what mess I towed through. Last trek across Montana in a blizzard netting 3.5mpg and less than 80 miles to a tank, I bought a duramax. Lol. Those numbers are pretty impressive for a 8.1 comparatively. My LBZ under the same trailer empty has gotten 12-14ish. 10-10.5 under my flatbed with varied loads (8500k empty) and lowest of about 9 grossing 25k. But comparing the two trucks pulling loads wasn’t even fair in my case. Does the 8.1 really do that much better than the 6.0?

Edit: my enclosed trailer on that Montana trip weighed 6500lb empty, about 12k loaded.


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I had a Denali quadrasteer with 6.0 and 4.10's, it could pull a house down but it got 4.4 mpg pulling a 25' boat @ 65mph. That is also why I got a Duramax, power was there economy and longevity of power train was not. Lol...
 

matthew86

Member
Mar 16, 2018
55
2
8
Eastern WA
Have any of y’all seen Ford’s new 7.3 gasser? Can’t remember the whole marketing wank, but basically they went to a push rod V8 and were talking up durability and cost effectiveness vs the powerstroke. Seems like Ford has been wanting to make things as small as possible lately and DOHC, turbos etc, then pushrod 7.3. I’d be curious to drive one


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matthew86

Member
Mar 16, 2018
55
2
8
Eastern WA
I had a Denali quadrasteer with 6.0 and 4.10's, it could pull a house down but it got 4.4 mpg pulling a 25' boat @ 65mph. That is also why I got a Duramax, power was there economy and longevity of power train was not. Lol...



Even after I got my LBZ, the best thing I did to it was a 52 gallon titan tank. I still have my 6.0 with a little Maggie on it, I haven’t sold it because it needs a little work, but also I keep eyeballing my scout and thinking how it needs a little more power than the 350 that’s in it....I’d probably never notice the mpg on the 6.0 again.


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