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Discussion Starter #1
Hey CMNTMXR57 I notice in the BS thread you were talking about bad fuel milage with your 8.1. Just what kind of milage do you get? I have an 01 155"wb GMC Savana 3500 with an 8.1 that I use for a service truck. It weighs 9300lbs. and I get 10-11 mpg in town and 14-15 on the highway. The only thing I've done to it is Hypertech programming. I also ordered 3.73 gears hoping for the better fuel milage as there were no ratings for it.
 

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That's pretty good. Our Sierra Denali 6.0 averages 12.8.
 

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Discussion Starter #3
lively said:
That's pretty good. Our Sierra Denali 6.0 averages 12.8.
I've had alot of guys around here that have 6.0 in thier 2500/3500 trucks that say they wish that they had the 8.1 because of the closeness of the fuel milage and less tourqe.
 

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I've gotten 11 on a good day but my last tank was 6.6mpg.

Admittedly though, I was running around in 4WD that entire weekend because of the snow we got.

I also have a very heavy foot.
 

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I've got a 3500 crew cab dually with the 8.1L/Allison and get 10-12 in the city and right around 16 or 17 hwy if I'm not towing anything. I was impressed with the mpg since the truck has 4:10 gears. The 5 speed auto makes all the difference in the world.
 

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Yes, it does. I've got the 4.10's also.

Considering all the torque this thing makes, I'm exstatic when I get 11mpg. :D My best 1/4 mile pass with it at 7,000lbs and 60psi in the BFG's was a 15.84 and the best part about it was that I smoked the punk in a riced out Honduh next to me! He was humiliated back in the pits by his friends!!
 

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Discussion Starter #7
tterbo said:
I've got a 3500 crew cab dually with the 8.1L/Allison and get 10-12 in the city and right around 16 or 17 hwy if I'm not towing anything. I was impressed with the mpg since the truck has 4:10 gears. The 5 speed auto makes all the difference in the world.
Thats one thing GM couldn't put in my van was the allison transmission. I was hoping they could so I could have a more reliable tranny, but with 85000 miles so far I haven't had a single problem.
 

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The Allison is a Godsend for towing and hauling. The 4L65 and 85E's are great transmissions, but when strapped to a 15,000lb trailer, they pale in comparison. :D

The one problem I have with the Allison is flat out performance related. It's shift patterns and algorythms are set for those heavier load requirements, as such, I find it shifts about 700rpm too soon in each gear during little stoplight drags. If it could hold another 700 or so at WOT, that thing would simply scream. Also the Allison does rob a bit more power than a standard Hydramatic unit. But then makes up for it with a PTO, grade braking, ease of maintanance, and a couple other things. :)
 

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My Corvette gets about 12mpg and if I hooked it up to a 15,000 pound trailer it would just pop or something. Want to buy it?? This car needs to go!!
 

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My '94 4X4 2500 Suburban with 454 gets about 9.5 towing and 13.5-14 highway (we went to CA last fall at about 75mph and got that. Closer to 12 regular driving. It has 373 gears too. The towing is race car to Bonneville salt flats. 2200 miles each way.
 

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What kink of race car, the GN? I've always wanted to go to Bonneville, but never had the opportunity. My sister in TX has a suburban. Instead of license plates, it came with a ZIP code.
 

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mistermike said:
What kink of race car, the GN? I've always wanted to go to Bonneville, but never had the opportunity. My sister in TX has a suburban. Instead of license plates, it came with a ZIP code.
Have run a couple of things. Started in 1979 with a stock body (ran altered class because grill and headlights covered) Cosworth Vega. Set 3 records '79 and '80 running gas and methanol, best 138 and 143 mph. Then built a streamliner, first running 1 liter (took 2 pistons out of the 4 cyl, 2 liter engine) and just set open record at 145 mph on short track using only 2 of 4 gears (car geared for 200+). Heavy car, small no torque engine slow to get going. PUt the other two pistons in it, went 193 with 3 gears and were in the process of changing the rear to try get over 200 with better acceleration when it rained, ending the meet. Next year put a blower on it and then over the next 10 years and about 8 trips to the salt still hold blown gas 2 liter record at 250mph. Have been over 270 couple times (clocked) and 260 a bunch. Trouble backing up qualifying runs with things breaking. The car is now gone (money toward the GTO). I have a '86 firebird we have played with a little, same engine, and gone 131 at Maxton with ECTA. Is currently in the garage waiting for me to put engine back together. One of these days. But can only manage one obsession at a time and currently is GTO. :thumbs:
 

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My hat's off to you, Sir!
 
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