VCCA Home Forums TECHNICAL - 1945 AND NEWER 1990-Current Tow Vehicle Mods for better MPG?

Well I am getting my 2009 GMC Sierra 2500 6.0 Gas (Same thing as a silverado just different badges)ready for the run to Flint. I was toying with trading it in and buying a diesel, but had to pay income tax this year and that was the end of that thought. I am considering installing the following in attempt to increase from 7.7 MPG when towing

1. Cold air intake most likely an Airraid, nobody make the intake just the box for the 6.0 Mechanical fan is the problem

2. Edge Tuning box www.edgeproducts.com

3. Gibson Exhaust (cat back)
The total cast should be around $1,200 to $1,500
Anythoughts?
Thanks
John

John, That MPG must be towing? The big question is the cost of getting the extra MPG vs. Gas (extra fuel saved). If you increase your mileage to 10. MPG, a 2000 trip will save you $239.00 in gas(gas cost of $4.00 gal). If you gain another 1 MPG you would save another $72.00 on that same 2000 mile trip. in all comes down to how many miles you drive a year and how long do you plan on keeping the truck. To me it would take 15,000 miles and getting 10 MPG to cover the cost of attempting to increase mileage. Either way, the cost to drive is getting more expensive everyday. I'm in the trucking business and its a daily struggle with the cost of fuel and mileage. Good Luck Don

I tow with a gas truck too so have been down that road and as stated, the cost vs payback is a consideration. On the plus side, many things that improve mileage also help performance for normal driving.

You need to really do your homework on aftermarket air boxes and filters. Lots of hype and advertising and most only lead to louder intake noise(often unbearable when towing) and most offer very, very poor filtration so you are ultimately sacrificing engine parts. There is a reason manufacturers build them the way they do and they have access to the same data as aftermarket builders.

The EDGE is a good device. Especially nice to have the extra gauges and ability to choose what you'd like to monitor. I really like mine and the towing mode helps performance greatly and improves mileage.

Your standard tuneup items like fresh plugs are significant. If there is any mileage on the truck, pulling the injectors and having them sonically cleaned and flow tested/matched makes a big difference in both mileage and performance. Same with fresh oxygen sensors if you have more than 60k miles.

I've done all of the above with improvements in towing and mileage. I also run synthetic fluids everwhere possible - engine oil, transmission, power steering, transfer case and differentials.

Tire pressure towards the maximum rated on the TIRE (not the door tag) helps with mileage and can extend tire life when towing. Obviously a harsher ride and will change handling characteristcs when unloaded. Check the RV forums on the web as there is lots of info. Nitrogen fills may be worth looking at.

Obviously proper weight distribution to both truck axles as well as level trailer are important. I laugh how badly 9 out of 10 trailer combos are set up on the road. It's scary.

Exhaust can make the biggest difference but with a big cost. A performance Cat-back system will help a wee bit but factory manifolds are a bottleneck. Ideally long tube full headers, high performance cats and true dual performance mufflers will give you the best improvement but biggest cost, extra noise and potential for leaks at the head area.

You could also experiment with going from regular gas to a mid-grade and see if anything changes. Generally you'll get the best performance and mileage with the regular grade unless the computer senses a knock on regular and retards your timing a bit. Thus the experimentation. Forums specifically related to towing and your model truck will help you see what others have found with Octane. Avoid discount gas.

Sounds like you have a mechanical cooling fan. A dual electric kit would definately help for normal everyday driving - lots more power and better mileage. For towing, the mechanical fan is most reliable. If this truck is your daily driver, electric would be the way to go. If you only pull the truck out to tow or occasional use, then the mechanical is best.

Didn't take long to spend thousands of dollars and weeks of time did it!

I found that having the regular tuneup items fresh, tire pressure high, synthetic fluids and the EDGE worked well for me. I bought my EDGE used locally on Kijiji for $150. KIds buy them and then need gas money so liquidate them! My dual electric fans and cat-back exhaust sit in the shed. I also got these used but after more research decided were not worth the tradeoffs installing...

I first would check the engine as 7.7 is about 30% less that I got from my '99 Silverado with 6.0 engine, long bed extended cab. I was pulling a '24 foot 8.5 ft. wide 7 ft. tall enclosed trailer with 7-10k load. The mileage varied from ~ 9.5-11 mpg depending on terrain, speed and load. I typically ran at 65 mph. Yes, I understand that my experience was mostly with 0 Ethanol which gives 10% or so less mileage.

I have since used two Duramax Silverado 2500 HD crew-cab, long bed trucks with the same trailer. The '04 is still in the family with nearly 200k miles. Now use an '08 crew-cab long bed 2500 HD. It pulls much better (higher HP and torque) but gets ~ 10-15% less mpg that the '04 (and then there is the additional 10-15% less than the higher sulfur fuel available prior to '08). I did a calculation on cost versus gas truck back when diesel was lower cost (except late summer and fall when oil companies were gearing up for winter heating oil). It took ~ 150k miles for diesel to cost less than gas when total costs (purchase difference, service and fuel cost) were considered. I therefore advise those in the eastern 2/3 of US to use gas and only when there is a lot of towing in mountainous areas to pay the premium for diesel power.

John-the best $400 I spent was on an EDGE programer for my 1998 one ton with 7.3 ltr diesel with a 15 foot box that originally got 8.5 mpg, and after installing and setting at 60hp it consistantly averaged 12-13mpg for another 350,000 miles plus there was a very noticeable and significant increase in power.

hoppy

The engine is good I bought new in 2009 and it has 18K on it. I did get as good as 8.9 towing, pretty much the 7.7 is distorted becasue the last 50 and first 50 miles of every trip is traveling through the Greater New York City area so stop and slow go at around 20-30 miles an hour is the norm.

I had read about the edge box and the diesel guys swear by them but I never heard anyone use one with a gas truck. They claim it to be plug and play, with no voiding of any warranties on the vehicle. I was told to get the one with the back up camera and tell the dealer use it for that purpose if there is any problems.

Keep the advice coming guys, the airintake I am going to opt out of.
John

Looks like I am going to go with the Edge CTS. I just read the instructions on line and they clearly state that if you run the unit with a cold air intake or exhaust mods that the it could creat a "too lean of a situation and cause damage" That the unit is designed to be used with the stock equipment. We will see......
John

John,
Do you get ~15 mpg running empty at highway speed. If so that is what I would expect with today's gasoline. I would think that ~ 9 mpg with loaded enclosed trailer is in the ballpark for factory engine setup. I assume you have the 3.73 rear axle with the towing package. If you have the 4.11 then the mileage will suffer a little as the rpms at a given speed are lower and the transmission even in towhaul doesn't adjust properly for the load. I sometimes manually shift to get a better HP torque range. Feel that gives me a bit better gas mileage and surely better performance. The factory computer program is set for gas mileage unloaded even with the towhaul mode. I sure would like to talk to a factory engineer to know why they programmed the computer the way they did.

Chip,
Highway I get around 14-17 empty. Yes I do the have the 3:73 rear. I am still mulling around buying the box.
John

John,
All you have to do is remember to pull up the anchor before starting to tow the trailer. Dragging that thing just makes a bunch of sparks, draws attention and reduces the gas mileage. Just kidding. Looks like everything is okay. Sure takes a bunch of miles to pay for all that performance stuff particularly if gas mileage increase is the prime motivating force.