gas mileage

[HANK1948]

i just bought a 96 crew cab dually 4x4 it a amsoil filter and a aftermarket muffler its in great shape and runs great but it get only 14mpg. i know people with simular trucks that get 18 is there something i can do to improve it i drive it easy, i dont go any faster than 70 on the highway is there a chip i can get or something? :eek: jkchenry@earthlink.net

[catmandoo]

maybe they have better gears in the differentials,the lower the rpms the better mileage. also your post heading should have been fuel mileage not gas milage.

[LanceW]

that doesn't sound too low for a stock 4x4 CC dually... in mostly short-trip driving that's about what I get empty with a 4.10 rear, I maybe get as high as 17 on the highway at 70mph.

Try a fuel additive with a Cetane booster, that will give you a little milage kick and make the engine run smoother. I've been using Power Service (finishing a case) but many on this site swear by FPPF and some others.

on edit: fuel milage claims have a way of getting inflated sometimes, not necessarily on purpose or with malice- people just have a tendency to "round up". That said, there are people out there who have done some airflow/turbo boost mods who really are getting 18, 19 and up.

[ 09-23-2003, 05:04 AM: Message edited by: LanceW ]

[slagona]

14 MPG is very common for duallies with a 4:10. The best I ever achieved was 16mpg with that configuration. Like catmandoo said, the key is in your rpm's. Keep them at 1800 and you'll see an increase in mpg. My problem is that I drive at 75 mph or better 80% of the time. Even with my 3.42's, I run at 22-2300 rpm most of the time, so I average around 17 mpg. If I cut it down to 55-60 mph, I can get over 21 mpg - but I'd rather go faster than get better mpg.........

However, if you compare your diesel to a gas truck with the same configuration and driving habits, you would be quite happy with 14 mpg.

There are several ways you can increase your mpg:
1) drive slower
2) change differentials
3) go to a taller tire (sometimes harder with a duallie)
4) install an overdrive unit

#1 is free, but requires patience.
#4 is the most expensive ($2500 - $3000 min) - it takes a long time to get you money out of the fuel savings
#2 is also costly ($1000 - $1500 min) and affects your towing capacity
#3 won't affect your mileage much (3-5%), but it's something and if you need new tires anyway..... Make sure you recalibrate your odometer if you do this - makes things much easier.

People tend to forget that if they were driving a gas vechicle, it would be worse. If you're looking for mpg, don't buy anything with a lower ratio than 3.42 - Some people are able to get 18 mpg or more with 4:10's, but they are few and far between (or exaggerating....)

Good luck with your truck - and enjoy it!

[Johnny B.]

I can't get any better than 14 mpg with my dually either. The previous owner said that he got 16-17 mpg empty, he was in his late 50's and accelerated just enough to get past idle.

[pgoldstein]

My CC Dually gets just about 14 mpg @ 70 mph empty.

[jeffreydmet]

Look at this thread
What's your fuel mileage with a load?

I started it with the same problem and learned a lot.
Also from this thread I found out that duals cost a couple of miles to the gallon. Check out this thread also.
Changing from duals to single rear wheels?

When I got mine 14-15 was about all I got. I have changed gearing, TDC offset, running fuel conditioner, am running with a spacer in my exhaust Cat flange to simulate a larger pipe, have the outer duals removed, and removed the bug sheild. This configuration got me 19mpg on the interstate. I've noticed that removing the duals made the biggest difference.