Gas mileage on an a 8.1?

[8100 Power]

Has anybody used any good mods for gas mileage, im getting about 11 right now, im looking for better mileage, im fixing to put BF Goodrich AT Ko's 285s. Which isn't going to help any

[linda]

the best thing to do is drive it to the dealer and trade it in on a VW golf. Other than that, feed the beast....it was made for power not fuel economy. I would be happy with mine if i was getting 3MPG.

[dannyukonxl]

thats why i drive an econobox volvo s40, its fast when you stomp on it.... last fill up all city driving was 20 mpg, the suburban sits at home

 

anywho, exhaust and intake and westers chip will help a lot

[Haulin' 8.1]

Well here's the things that have helped me improve mileage since I got my 50K 2001 about 3 months ago. 90% of my driving is stop and go with 2-5 mile streches, about 20 average a day. MPG figures I give are approximate because I did figure them out but I didn't keep detailed records, I'm going by memory.

As obtained about 9.25 or less, speedo was off. But it was scary.

 

Used Hypertech Programmer to correct for tiresize, 285's. Don't underestimate the difference this makes.

MPG about 9.6

 

Reduced tires from ProComp 285's to Bridgstone 265's. More accelleration torque, engine stays in sweet spot more, less wieght to accel. See if you could live with this size.

MPG about 10

 

Replaced fuel filter and flushed fuel injectors with a professional type rail induced cleaner. Big difference, I'm a engine tech and I'm used to seeing good results with this but at higher mileage. I started thinking about it, this truck was getting just over 10 MPG at that point and at 53K miles it's used as much gas as an econobox at 110K so I did it and it really picked up and smoothed out. Power and mileage, quieter exhaust at all speeds.

MPG about 10.5 to 10.8

11 on a long trip.

 

About a week and a half ago I was going back to the shop from lunch and the truck just stalled instantly and wouldn't start again with cranking. I coasted into a parking lot and tried a few more times then ate my burger. After about 5-10 minutes it started right up and I put it on the scan tool back at work. No check engine light but the crank sensor had set one failure record. So I had the Ms. bring one over since she was just passing the local GMC dealer on the way home. It was a moderately difficult crank sensor install but holy improved ignition timing, what a difference. It was one of those "I didn't know what I was missing" type of deals. Exhaust note got quiter still.

 

I'm not sure of the MPG yet because I've been having fun with all the power the truck has came unto now. It was already "fast" relatively for such a huge and heavy vehicle, I've got a Harley wieght in bumpers alone. But with each step I've taken the power has gone up. Now I can report with certainly that it's fast period. It's like a jumbo jet going for takeoff, no super burst of power at launch but accelleration just keeps climbing along with the speed. I've been putting the truck to the test against anyone who will give it a run from a light and having too much fun so no mileage report as of yet. I just filled it up two days ago and have been driving more conservitably so sometime this week I'll have a figure. Last night I made a turn behind a '93ish Nissan Maxima and we both were gunning for a light notorious for turning red shortly after ours goes green. We had three lanes to choose from so there wasn't a battle going on just two guys trying to beat the light. Right off the bat he put about 4 cars on me but once I hit third I was flying by him like he wasn't even in it and beat him threw it. Sorry I'm getting way off topic. Too much fun, but have a scan ran on yours to see if there's any issues you may not be aware of like that.

 

Next thing I'm doing is putting in fresh plugs, in my experience 55K is pushing it for an engine that makes this much power and is used under load at times, regaudless of the optimistic tune-up schedules the manufacturers put out. I'll run a slightly reduced gap to reduce misfires, especially under WOT since I seem to like it so much.

 

Oh, and I just scored a Volant intake system on Ebay for $91 so that will be in this week also. I wonder how much MPG that will be worth? I've search many forums and webbed tailgates actually hurt but tonnou (spelling?) covers help.

 

Vernon

[8.1Texan]

Has anybody used any good mods  for gas mileage,  im getting about 11 right now, im looking for better mileage, im fixing to put BF Goodrich AT Ko's 285s. Which isn't going to help any

 

<{POST_SNAPBACK}>

 

 

 

11...i wish i was getting 11!! I get between 8 and 9, of course my commute has a stop light every 10 feet and a whole lotta hills, and when i do have an open stretch on the weekends, i gun her for everything she's got.

[Daubs]

Ordered my CC 2500HD 8.1/Allison from factory and got her March 13th. Had t-bars cranked, swapped out 245's for Revo 285's right at the dealership.

 

Was getting 8.5 MPG around the city (lots of stop and go, small town, averaging around 22-25 MPH per tank). As the truck got more miles my MPG got better. Remember, I haven't changed computer to compensate for larger tires. Been getting 9 around town and have ~6,300 miles on it today.

 

I did run a long trip on highway and tracked miles with my GPS. Got 12.5 MPG on that run going 85+ most of the way, so I was really pleased.

 

Installed Volant and saw my city number climb to ~9.5. I check MPG at every fill. Buddy of mine has same truck, except for his 6.0L engine. He's getting 11-11.5 city AND highway, so he's pretty pissed I'm getting over 12 highway.

 

I plan on getting Westers soon. I'm very happy with my big block. Powerful and I can't complain about MPG. Friends had old big blocks (454's) and got 6-7 MPG.

 

My dad had '76 HD K-20 4x4 regular cab long box with his construction box on back. Had all his tools in it 24/7...and got, are you ready for this, a whopping 6 MPG! That's city/higyway, uphill/downhill, wind-at-back/in face, high tide, full moon, you name it...SIX!

 

My truck in an LT with XM, DVD for kiddos, full leather, you name it. It's a great ride and I'm never going to bitch about 9 MPG.

[Chev8.1]

See sig below for mods.

 

Best observed Mpg 15.8 (all highway)

best in-town 11.5-10 mpg

 

Avg mpg 13-14 mpg

 

avg highway 14.5 mpg

 

worst mpg 3 mpg (mudding)

 

Did not start getting good numbers until started modding. Uncork the airflow. yes it will be somewhat more noisy.

[8100 Power]

Im going tomorrow to get an K & N Air Filter to replace my factory one, the guy says it will get 1 - 2 mpg better, i guess ill see

[THE BIGPUNN]

i put in a drop in k@n and installed a flowmaster muffler. went from 8.7 mpg to 9.2. besides that, i try to put er in cruise control as much as possible and take er easy on the gas..... yah, right!