I have a CCSB 02 2500 HD 4x4. 5 spd Ally. I can't get MPG for crap. I get 8-9 on hwy or town...no difference. I see some of you all get 10-15 with your 8.1 WTF can I do to get some better mileage?

I am same with you 8-10 loaded, highway, unloaded, city , mix it dont matter just stays the same. Not sure how any of those guys get that milage as they claim.

I am same with you 8-10 loaded, highway, unloaded, city , mix it dont matter just stays the same. Not sure how any of those guys get that milage as they claim.
Yea, i wish I knew. I would kill for just 12mpg

what all you done to your trucks? my 496 i could avg. bout 13mpg. i pulled the cats out and it dropped to about 10 hwy.

i also have 3.73 gears. if you got 4.10 goodluck

Yep, I was one of those who had the 4.10 locker option and would only get around 10 mpg...boy, but I could pull just about anything.

I am one of the high mileage people... (14-15 commuting).

I do have 4.10s but the 4L85E. And slightly lighter Av. (still 6600 lb or so),

I would say the keys I have found:

Light throttle starts. Let the auto shift around 3k rpm or sooner.

Keep highway speeds down 65-70 seems to work well for mine (75-80 will drop me back to 13-14).

Break that sucker in! Mine got much better milage after towing with it. (redline for miles on end going up passes).

Tire pressures of 60 -80 psi

Low octane fuel (I use 85)

If its older, may want to check the usual, air filter, fuel filter, plugs, wires, etc.

I also run a Hypertech P3 tuner on the 87 octane setting which seems to help 0.5-1 mph.

Tire size and any accesories that impact drag coeffeicient. will have a big impact.

I'm almost sure it has 4.10 gears, and the tires are 285's on 16's.

generally if you run 70mph at 2000 rpm, then you have 3.73, if your running at bout 2300-2500 rpm you have 4.10

generally if you run 70mph at 2000 rpm, then you have 3.73, if your running at bout 2300-2500 rpm you have 4.10
yea then, def 4.10

others mite argue but if you drive alot u mite wana look into getting an allison 5 to 6 speed conversion

others mite argue but if you drive alot u mite wana look into getting an allison 5 to 6 speed conversion
..........seems like alot of money for another gear....but I don't know, might be woth it

i've rebuilt several allisons, and i'd like to do it myself. but i think if you can get a remaned 6spd, with an 06 TCM it mite work. still talking to a friend of mine at GM Detroit bout it

i've rebuilt several allisons, and i'd like to do it myself. but i think if you can get a remaned 6spd, with an 06 TCM it mite work. still talking to a friend of mine at GM Detroit bout it
yea, how much $$$ would that be?

just a few shinny pennys. bout 3gs for the tranny and mayb 1g for TCM. suncoast has the conversion for i think $1800

i think I am screwed either way!

all you need for the conversion is a 6 speed valve body and TCM. thats all

all you need for the conversion is a 6 speed valve body and TCM. thats all
could i get the valve body out of a 6spd?

To OP....your not going to get shit for gas mileage in a truck that weighs around 7K# and has a motor thats got almost 500 cubic inches. Take it for what it is and enjoy the power. You can spend $10K and not get anymore than 2 mpg's. You can get EFI Live but that doesnt really help around town but rather on freeway. All these power adders that say increased mileage are lying...trust me I got em or had em. These trucks were made to haul not to win awards for gas mileage :D

the best i even got was 13.5 haulin ass on the freeway unloaded, i had 285's on the stock 16" rims. i went with hummer rims and a 295 and i dont get much better that 11.5 on a good day driving the same conditions, hard to believe but thats my story.

average about 10 now. cleaned my MAFS and didnt help ..

Running unloaded, 2001 3500 ext. cab dually, 4x4, 8.1/Allison 5 spd. 4.10's... 140 miles out on back country roads, 50 miles at 75 mph.... 11.4 mpg

see.....i would love that

Rare

The problem is 3 numbers. (496) That is a big powerful V8.

The problem is 3 numbers. (496) That is a big powerful V8.

OR 2 numbers and 2 characters.... 8.1L ;) :D

ender06 id also take a look at you fuel pressure regulator on your fuel rail. i seen those go bad, dont throw codes and mileage drops. cost bout $50 at parts store.

Running unloaded, 2001 3500 ext. cab dually, 4x4, 8.1/Allison 5 spd. 4.10's... 140 miles out on back country roads, 50 miles at 75 mph.... 11.4 mpg

Now take this same truck with a 43'l x 8'w x 8't, 15000# horse trailer at 70 mph from N.C. down into Fl. and that 11.4 drops to 7.5-8.0 mpg..... I'll top off the tank every 200 miles.... That's about as far as I can ride without rupturing my bladder anyway.. LOL!! Love my ole' "496"!!
So what if one of those new style EPA approved, regen oilers pass's me out on the super slab, I'm running the speed limit!! I tell myself, "They're just trying to get back home so they can get to work so they can make that truck payment"! I'll keep that "big block" for a while... Don't make them like that anymore!! I'll take what I would be spending on a diesel truck payment and abuse that cash on some new toys... ATV's, weapons, fishing gear, horse trailers and tack, more weapons, etc. etc. ....... some more weapons!!!

Mine has the 3.73, I rarely go over 65mph, and accelerate slowly.
Hand calculated 12.9.
It's nice having the power there when needed though.
When I'm playing, I don't want to know the mileage.

Couldn't hurt to check your speedometer against a GPS. Those 285's are throwing your speedometer off - probably by about 5% to 6%. Maybe a small thing but it means that your milage is actually a little better than you think.

Would it be wise to switch rear ends? Does the 3.73 come in Posi or Gov-Lock. I am getting ready for a turbo setup so I don't want an open differential. As far as towing, I think I could live with the 3.73

Good mileage on the 496 is simple physics. Small tires inflated fully, small mirrors and bumpers. No extra 4wd weight. Don't carry unnecessary heavy gear. Smaller cabs and beds. Stock engine in good tune. Synthetic lubricants. Manual trans. Drive conservatively giving yourself room to coast as much as possible to avoid stopping at lights etc. I wouldn't be suprised to get 14+ hwy on a rwd regular cab stick 8.1. Mine is anti mileage gets 12+ hwy on gas, 10 Hwy on E85 driving fast. In stop and go or towing it drops 15-20%.

Vernon

Isn't there a difference in winter fuel as well? I have always heard the the "winter mix" fuel burns faster. I know my mileage gets worse in the winter and I don't think it is from the little bit of time I warm up my vehicle??

Would it be wise to switch rear ends? Does the 3.73 come in Posi or Gov-Lock. I am getting ready for a turbo setup so I don't want an open differential. As far as towing, I think I could live with the 3.73


My 8.1 had a 3.73 and locker, so they are out there. I'm just not sure if any of these mods will work out cost-wise for better milage. I'm thinking that you may see a small increase, but not enough to get a payback over a reasonable length of time. You certainly will not see as much MPG increase compared to just driving more conservitively. The 8.1 just sucks gas - best I could ever do with steady, unloaded highway travel was 12.75. I averaged just under 10 for most conditions.

the best way to get good millage in the 8.1 is to park it ... there really isnt much to do for it just driver her and have fun :D

I'm almost sure it has 4.10 gears, and the tires are 285's on 16's.

If you have not corrected your speedometer that could be your problem because of the larger tires you are going farther than you are indicating. I get between 12-13 on the hgwy and about 10 combined.

Yep...theoretically, a switch from 245/75R16 to 285/75R16 is a difference of 1.0775 in terms of miles traveled. So, for example, if your tripmeter shows 300 miles, you've actually traveled 323.25 miles.

Of course, all brands of tires vary a bit in size, and they also vary depending on inflation pressures and loading, so you really need a roll-out measurement to get it right.

Really, that helps alot. Didn't know there was THAT MUCH of a difference!

What is stock usually on these trucks? 265's or 245's??

245

I gave up trying to get good milage...I just try not to drive much,,start taking the wifes 30+mpg car on trips..Even though we take my truck 90 % of the time around town..thankfully price of fuel is down from last summer..I have gotten 13.5 one time...since the lift kit ,,efi,,i get 8-10,, its just too much fun to drive ,,never changes..stop&go traffic killes it,,but it sure is FUN to light up those 35's w/posi .....:)

I gave up trying to get good milage...I just try not to drive much,,start taking the wifes 30+mpg car on trips..Even though we take my truck 90 % of the time around town..thankfully price of fuel is down from last summer..I have gotten 13.5 one time...since the lift kit ,,efi,,i get 8-10,, its just too much fun to drive ,,never changes..stop&go traffic killes it,,but it sure is FUN to light up those 35's w/posi .....:)
Trucks looking good man! Love that lift and wheels...we gonna have to get together sometime to bullshit

i also have 3.73 gears. if you got 4.10 goodluck

I have 4:10's, and running 35's and get 11mpgs consistently,
gotta love regular cabs and ZF's :D

I am one of the high mileage people... (14-15 commuting).

I do have 4.10s but the 4L85E. And slightly lighter Av. (still 6600 lb or so),

I would say the keys I have found:

Light throttle starts. Let the auto shift around 3k rpm or sooner.

Keep highway speeds down 65-70 seems to work well for mine (75-80 will drop me back to 13-14).

Break that sucker in! Mine got much better milage after towing with it. (redline for miles on end going up passes).

Tire pressures of 60 -80 psi

Low octane fuel (I use 85)

If its older, may want to check the usual, air filter, fuel filter, plugs, wires, etc.

I also run a Hypertech P3 tuner on the 87 octane setting which seems to help 0.5-1 mph.

Tire size and any accesories that impact drag coeffeicient. will have a big impact.

I have the same truck without any of the hypertech stuff. Actually also have H2 wheels with 285/75/17's on it which probably made potential mileage worse. For some reason in the winter I get 14-15 consistently with some trips to the mountain to snowboard thrown in. In the summer it drops to 10-12 (romping on the gas more than anything).

If I floor it all the time I get back into single digits. When I first got the truck I was always in the 10mpg area. Changing the spark plugs and general tuneups yielded a significant change though as time went on, even with the heavier wheels and tires.

However, nothing you do is ever going to turn it into a Prius. I would bet 15 on the highway is the most you will ever see and 10 in town.

My stepdad has an 01 cc/sb and gets about the same as everybody else in here.

plan on going to the jamboree this year in lima,,send me a pm,,we will hook up.you wont miss the truck it will be there..Trucks looking good man! Love that lift and wheels...we gonna have to get together sometime to bullshit

My dad has an 05 8.1, 4.10, ally, 8-10, but we are building contractors and do alot of around town and back roads. The best avg. I have ever seen on the DIC is 12.5mpg

So I changed my plugs yesterday, can already tell a little improvement, but haven't gone far enough to tell

Now take this same truck with a 43'l x 8'w x 8't, 15000# horse trailer at 70 mph from N.C. down into Fl. and that 11.4 drops to 7.5-8.0 mpg..... I'll top off the tank every 200 miles.... That's about as far as I can ride without rupturing my bladder anyway.. LOL!! Love my ole' "496"!!
So what if one of those new style EPA approved, regen oilers pass's me out on the super slab, I'm running the speed limit!! I tell myself, "They're just trying to get back home so they can get to work so they can make that truck payment"! I'll keep that "big block" for a while... Don't make them like that anymore!! I'll take what I would be spending on a diesel truck payment and abuse that cash on some new toys... ATV's, weapons, fishing gear, horse trailers and tack, more weapons, etc. etc. ....... some more weapons!!!

I think you're taking the money you'd be spending on a diesel truck payment and dumping it down your gas tank.

I think you're taking the money you'd be spending on a diesel truck payment and dumping it down your gas tank.
Yup but theres no replacement for displacement :D ;)

!!!!!Guys, check this out!!!!!!! I changed from Castrol 5w-30 Syntec (thought it was good stuff) to a heavier 10w-40 Mobile 1 Full Synthetic. Let me tell you what, mileage JUMP. Went from the crap-ass 7-8ish mpg, to 12.5 on the first tankfull after the oil change. Consisted of all sorts of driving. Not GREAT, but definetely BETTER. I will swear by this stuff now. You might say it wasn't the oil, but that is THE ONLY thing I changed.

!!!!!Guys, check this out!!!!!!! I changed from Castrol 5w-30 Syntec (thought it was good stuff) to a heavier 10w-40 Mobile 1 Full Synthetic. Let me tell you what, mileage JUMP. Went from the crap-ass 7-8ish mpg, to 12.5 on the first tankfull after the oil change. Consisted of all sorts of driving. Not GREAT, but definetely BETTER. I will swear by this stuff now. You might say it wasn't the oil, but that is THE ONLY thing I changed.
If the oil made that much difference I would really be concerned about what damage has been done.

so i must have a good one cause i drive her hard... real hard and get like 8-9 in town and 13-14 freeway... and the 14.0 hand calc. was at 72 mph speedo(have 285 bfg's tho) and pulling a flatbed aluminum uhaul car dolly

If the oil made that much difference I would really be concerned about what damage has been done.
Yea, it makes me wonder. I guess we'll find out in about a week when the rear mount turbo goes on. It might blow it all to HELL!
so i must have a good one cause i drive her hard... real hard and get like 8-9 in town and 13-14 freeway... and the 14.0 hand calc. was at 72 mph speedo(have 285 bfg's tho) and pulling a flatbed aluminum uhaul car dolly
Yea, you are one of the luckier ones.

hello! its an 8.1! a 496! its not gonna get 18 mpgs. if you want higher mpgs get a dmax.:rolleyes:

hello! its an 8.1! a 496! its not gonna get 18 mpgs. if you want higher mpgs get a dmax.:rolleyes:

:funnypost But true...

3.73's here with 35" tires... pull upwards of 10K often, pulls fine but I don't care to ck my mileage. Only time I checked it I got 12.9 with 33" tires.

This one cost $700/month but it's paid for, gas runs me 200-250/ month, new diesel will have payment+fuel.... I'll keep this one, besides if the engine blows a new one is roughly $5500

Besides Chevy blew their wad on design with the 01-02 HD's.... the rest look like crap

hello! its an 8.1! a 496! its not gonna get 18 mpgs. if you want higher mpgs get a dmax.:rolleyes:

Yes, but then you'll be faced with paying the higher per gallon price of diesel vs. gas. (close to $1/gal. higher here)

If you want economy get a small car.

Yes, but then you'll be faced with paying the higher per gallon price of diesel vs. gas. (close to $1/gal. higher here)

If you want economy get a small car.

Diesel is now .02 more than Unleaded. I'll deal with it. Last week it was .01 cheaper! :D

Yes, but then you'll be faced with paying the higher per gallon price of diesel vs. gas. (close to $1/gal. higher here)

If you want economy get a small car.

it is 10 cents higher here. i think i'll take a dmax

couple years ago read where couple of techs(6.0/8.1) were dealing with engine issues and could not figure it out, put fuel pressure gauge on set it up on hood drove trucks around. fuel pressure was dropping off, some FPRegulators had screws others did not, they wound up taking 1/4" socket that fit around vacuum line fitting and gave it smack. that caused fuel rail pressure to stay up and rough, intermitent running went away along with increase in MPG's. they reasoned that low injection pressure would allow misfire and use more fuel. might help.

fuel pressure was dropping off, some FPRegulators had screws others did not, they wound up taking 1/4" socket that fit around vacuum line fitting and gave it smack. that caused fuel rail pressure to stay up and rough, intermitent running went away along with increase in MPG's.

OK...sounds good, but I don't really understand exactly what you are trying to say.