Engine/Transmission (1994 - 1998) need more towing MPG

[WKunkel]

hey everybody I got some questions about fuel mileage while towing a 9,000lb fith-wheel trailer.



I'm going on vacation this year with my uncle who's just bought a 2005 duramax dually crew cab (mine a 1996 3/4 ton) both towing campers that weight close to 9000lbs. What do you all think is my best bet to get better fuel mileage? I know I could beat him in power but he's the kind of guy who thinks fuel mileage is everything.



I think if i advance the timing it will help but to what degree? i was thinking like 13. 5 or 14 degrees and maybe a different plate.

Thanks in advance

 

[sewman]

I would set the timing to 16,air all the tires to maximum press on both truck & trailer,don't take any extra weight,including water in trailer,start slowly & try to coast as much as to you & make sure you have some syn lube in the rear,

chack brakes f/dragging.

Drive safe & let us know what happens.

Bob

 

[bmoeller]

Welcome to the TDR!



15* seems to be the "magic" number around here.



I haven't touched my timing yet. It needs it. With all my fuel BOMBs, I gained a solid 2mpg. The new transmission has seemed to bring it up a tad.



What mileage do you get right now, with your current setup? What gear ratio do you have in the diffs?

 

[WKunkel]

right now I get about 10 mpg towing and about 15 empty.

my rearend is a 3. 53 i think.

 

[JJW_ND]

My two cents.....

If you are totally stock, or nothing more then a plate, get the timing set greater then 15 but less then 16. 5 or so should yeild the best economy, power, and safe for the engine. Timing yeilds the single best ecomony increase assumming everything else is not terribly out of spec. Running some fuel additive (amalgamated or Stanadyne) helps a little.



MPG have as much to do with driving then engine tweaks. On our 12V I have found keeping rpms between 1900 and 2100 (engine luvs 2K) will yield the best economy. Do not run with crusise. Pay attention to everything that make you more aerodynamic. Less wind resistance (this includes speed) has more effect on economy then weight.



ALso, make sure you take turns leading and following. I have found the followers sometimes get worse mpg because of always adjusting the speed.



If your speeds get to slow to run in overdrive/fifth and you will pay a big mpg penalty. High RPMS in 12V suck fuel. A steady throttle, keeping in high gear (locked with an auto) will yield the best.



jjw

ND

 

[Forrest]

Ditto on the timing.



WKunkel ... is yours a non-calif / 215hp pump? If so, i'm thinking a #11 plate centered would be good. I had one with the stock turbo & mileage was great. The #11 is mild on the low end for cruise yet has a good high end. Of course, it's slideable.



Another thing I found really helps is rt foot cruise control with your boost guage. Unless another 5'er is in the crosshairs, I like to limit boost to 20psi.



Another thing that helps mileage is a Valet switch. It takes the plate outa the equation. Great for flat to small hills stuff & safe with the cruise control.





Forrest

 

[WKunkel]

my pump is a non-cal. i'll try a #11 plate it sounds like what i need (or i could grind my stock one if i got some specs). What is a valet switch?You dont think 15 degrees is to much? Thanks,

will

 

[Forrest]

I'd just outright buy a #11. That curve & depth is sweet.



I don't think 15 is too much ... I'm running 17 & tow @ altitude ... no problemo.



A Valet switch is a 12Volt, vacuum solenoid that interrupts the signal to the AFC housing. I got mine from PDR. Easy install, works great! I put mine on the drivers side fenderwell.

 

[WKunkel]

what kind of mileage do you get hauling your camper?

 

[ndurbin]

Get ride of the cat and muffler. That'll help alot. Take your intake box off and cut holes in the bottom half to allow more air in. My truck pulls really strong from b/w about 1600 to 2100 RPMs so I usually keep it in the middle at about 1800-1900 RPMs. Which w/ my 3. 54 gears works out to be about 65 mph.



I get about 10 mpg pulling my stock trailer w/ a heavy right foot but thats about 10-15,000 lbs. depending upon the size and number of cows in there.



Nathan

 

[Suprmn]

The most efficient RPM for the 12V is 1750 rpm. If you can keep close to that RPM you will get your best mileage. An old issue of the TDR talked about this and I gained 4 mpg on my truck by keeping close to that RPM. It will keep you out of the fast lane, but you will see your best numbers there.

 

[hsmith]

With my wife's wigwam in tow, 14k empty, 65mph 4th over and just under 2k rpms, 11mpg. When I drive like I like to, usually a tad over the speed limit, just over 10. Just the truck around town, 18. 5 with no problem.

Smitty

 

[Cooker]

Another thing that helps mileage is a Valet switch. It takes the plate outa the equation. Great for flat to small hills stuff & safe with the cruise control.

You are having better luck than me because it has not done much to help my MPG's. Although I will have to admit that I thought it would.

 

[MLee]

See by your profile you have a straight ex,air intake everything forward, and 285 tires. How about an air dam, to help push the air over the the 5 ve'r? this will help some. have you calculated the difference of the speed "o" for the tires? or has it been corrected, for the mileage difference. A lot of the time it's in the right foot. Stay away from a head wind. This will kill mileage. I found on mine 62-64 MPH was good MPG good power was good, about 1850-1900 RRRRss. I run 265 tire. Tread makes a big difference, if its luggy, they tend to decrease mileage a lot. 1-4 MPG.

just my penny's worth.

Marv.

 

[Gene Arnold]

Aside from bragging rights, with a 40 cent to 60 cent difference between diesel fuel and regular gas, we need to do the best we can to maximize mpg.



I pull a 34ft. triple axle Airstream that scales just under 9000lbs with a 1996 5 speed, 4. 1 gear ratio, 2 wheel drive. My fuel mileage pulling is consitently in the high 13s and often up to 15. I run at about 2200 rpms (that is just over 60 mph on the speedometer).



Ditto on easy starts, but I never coast (if by that one means out of gear or clutch disengaged).