Increased Mileage????

[azjbrown]

I have an '06 GMC Duramax 2500HD 4X4 Extended shortbed. Currently getting 14-16 town & 18-20 hwy 65-75mph....getting 10-11 towing 30ft 5th wheel 50-65mph as roads permit up and down az mountains and straight-aways. Reading from Banks and others how 'ram air induction' and straigh thru mufflers help on mileage and pwr. I have plenty of pwr but would like better mileage. Does anyone know if these replacements of stock REALLY WORK or is it just more marketing?:confused:
Thanks.

[mjammer]

I can't say on the Banks stuff. From the research I did and what I read here, Kennedy's Custom ECM tune was the most consistent at improving MPG so that is what I have on order for my '05 LLY. Now I just need to get it in so I can hopefully start getting better mileage as well as a boost in performance.

Mark

[AKMark]

In another mileage thread, Kennedy spoke some words folks need to take to heart.

Even with a tuned up ECM, upgraded exhaust, intake, and other mods, you might (no guarantees) get up to 22-23 mpg. Higher than that, doubtful.

How much do all these items cost? $$$$ So how long would it take you to make up the cost of upgrading with an extra 1 or 2 mpg? If you drive 50K a year, maybe you'd pay for it sooner, but most likely it'll take you 2 to 3 years to pay for the upgrade you made.

Set the cruise right at 65, instead of going between 65 and 75, and you'll save more money now. Or you can shell out the money to get an extra 1 or 2 on average and it'll finally pay for itself in a few years.

In town, you gotta learn where your truck is happy, what RPM do you need to go to get up to speed efficiently, without taking all day. My Suburban, I don't take it above 1800 rpm unless I'm trying to get above 50 mph. Helps me get 17-18 back and forth to work, 9 miles each way, with lots of speed changes, 15-50 mph. On the highway, I can pull 19 as long as I keep it limited to 65.

Thats with a lifted Suburban and a fairly stock 6.5TD, nothing like the power of your Duramax. I should also note, I have 3.42 gearing, I wish I had 3.73's for a little more towing power, but I cannot complain about fuel mileage. If you don't tow all the time, you could swap a set of 3.42's into your truck, for probably close to $1K and you would probably see the mileage increase you are looking for, but again, it'll take two years or more to pay for that depending on how many miles you put on a year.

[mjammer]

Yep, a little less than 2 years is what the payback looks like when I ran the numbers. I am also trying to do the other items as well but for my driving (~6-7 miles to work), it hasn't made much difference yet. Towing or interstate, under 65 is much better for sure. I wish it was like my wifes new Acadia - she actually gets better mileage at 65-70than she does at 55-60.

[More Power]

Had long talk with a longtime member yesterday about fuel economy. He owns a 2004 LLY 3500 and frequently tows a 34' Montana 5th-wheel RV trailer. He's a retired trucker/business owner and is good at recording data.

He installed just about everything Banks makes for his truck. Monster dual exhaust, ram air intake, Ottomind-6 diesel tuner & Power PDA, Technicooler with 3" IC pipes. He also has the BD left side exhaust manifold. A big chunk of change for all he's done, but.....

He wintered in Florida, installed most of the stuff there, and hand calculated 16-17 mpg towing back to Virginia this spring. He tows at 60-65 mph. He also noticed the fan-clutch rarely if ever came on, where it did frequently with the OE intercooler. He tows with the Ottomind set on #3 and uses #1 when running unloaded.

He says local driving without the trailer returns ~17-mpg and Interstate mpg is 20-22.

Mpg sounds a bit high to me for a 1-ton dually, but I've known him long enough to know that he knows how to calculate fuel economy - and he knows how to drive a diesel for fuel economy. If he wasn't on the East coast, I'd do a full feature story on his truck and its mpgs. ;)

Jim

[azjbrown]

:)Thanks for all in information and experiences shared. I am looking to Banks ram air and exhaust and then maybe their 6 gun controller after testing the air and exhaust. If I pick up 2-3 mpg watching my driving it should pay for itself in just a few years and anything beyond that is gravy.

[vernj4]

1 week ago went on a short 250 mile trip from Kalamazoo, Mi to Flushing, MI. This round trip was driven at 62 mph on Interstate roads. Most of the time the cruise control was functioning.

Used mile markers and the timer in the dash to establish speed. For what its worth, the actual calculated speed was 2 mph faster that that indicated.

Stopped 4 times. Estimate 5 miles where driven in a town. To my amazement, the 250 mile trip required 10.33 gallons of fuel. Baring errors in my calculator, that is an amazing 24.2 mpg!

[Mark Rinker]

Your sample size is pretty small to make any claims on mileage. Your tank could have been really full due to incline of pad/pump, and the next fill could be as much as 1-2 gallons short due to opposite incline of pad/pump.

Its possible - but better to average 3 or 4 full tanks burned against accumulated mileage on the trip odometer.

The Duramax is certainly possible of peaks in that range - but you'd be hard pressed to maintain a 24mpg average, IMO.

[conway]

Plz help me to clarify my thinking. If I make a improvement that get me conservatively 1 mpg better than 15 mpg I currently get, that is a 6.67% improvement. If diesel cost $4.50 per gallon (conservatively) that means I save .30 per gallon. If my improvement cost me $1000, doesn't that mean my payback will come after driving 3,333 miles, or approximately 3 months not years?

[DmaxMaverick]

Plz help me to clarify my thinking. If I make a improvement that get me conservatively 1 mpg better than 15 mpg I currently get, that is a 6.67% improvement. If diesel cost $4.50 per gallon (conservatively) that means I save .30 per gallon. If my improvement cost me $1000, doesn't that mean my payback will come after driving 3,333 miles, or approximately 3 months not years?

According to your expectations and math, it would take 3,333 gallons of fuel used, not 3,333 miles driven , to break even (unless you are getting 1 mpg). Figure how long and how many miles you'll drive, to use that amount of fuel, and you'll have your estimate of the return. Years, not months.

[conway]

Duuh. Right. Thanks