Performace Chips

[PapaDa]

I bought a 2005 GMC 4 door 4X4 2500 Durmax last year in June, I had a 1997 for power stroke but wanted to get back to my roots GM, Well the trucks performance, ride and looks are great (BUT) the fuel mileage sucks. It only gets 15 MPG light truck on the highway at 70 to80 MPH. My old power stroke would average around 19 at the same speed. The GMC has way more power but not sure it is worth the loss of fuel milage with the price of fuel today. My question is has anyone found a chip that would maintain power and improve fuel mileage?
P.S. I have a 14 ft trailer that I pull my Yamaha rino on and pulling it at 75 MPH the milage drops to 10 MPG.. this is totally unacceptable. I pull a 20 goose neck flat bed with 12,000# tractor and get the same 10 MPG. What's up with this?

[markrinker]

You'll find lots of information about this topic by searching the forums. I don't consider your mileage to be out of range, based on the speeds you are requesting of the truck.

In addition to slowing down (if you want to) you might check the following to help reduce rolling resistance (friction).

1) Proper tire inflation
2) Synthetic oil and gear lube throughout driveline

Chipping will not help, probably hurt if you have a heavy foot.

Opening up the intake/exhaust and adding some boost to help burn the fuel more completely may yield some results. www.kennedydiesel.com has some nice solutions.

Try a unloaded tankful never exceeding 2800 rpm during acceleration, and 65mph at cruise. I bet you see 18mpg.

[Kennedy]

That and slow down. I know it is hard to do, but keep in mind, wind loads/HP requirements are much greater at 70 that 60 mph.

[Deansel]

Well, it may be within the fuel mileage range but, it is at the low end. We have the same truck config as you and get 20 mpg highway - unloaded running about 65 mph. We average 12 to 13 mpg pulling our 22' 5th wheel camper at 60 to 70 mph. Total miles so far is at 5k, just had the first oil change.

[More Power]

A lot of current diesel owners don't have a sense of what it was like back in the 80's, when towing with a non-turbo 6.2L diesel.

The 6.2 GMC I owned was a great truck, and would deliver up to 24 mpg when driven carefully (remember the 55 mph speed limit?). However, power, weight, headwinds and hill climbing ability were aspects we all spent a lot of time thinking about while towing back then. That 6.2 GMC would do pretty well towing our somewhat small travel-trailer, but wind drag was an issue I thought about all the time. While towing, 65-mph was all that truck would do at full-pedal, but it would run at 60 at half pedal. This let me know that the increasing rate of drag created a barrier at 65 mph.

It takes a lot of power to tow at 70 (that only becomes more demanding at higher speeds), and which the 6.2L could do once it was turbocharged, but fuel economy took a hit. While running solo, this 6.2L TD would deliver 22-24 at 65-mph, but fuel economy would drop to 17 mpg at 80 mph (once the 55 mph national speed limit was dropped [img]smile.gif[/img] ).

Speed hurts...

Jim

[PapaDa]

thanks for the info! Guess I'll just have to buy the fuel, cause I don't think slowing down is going to work. I would like to say that other than the fuel mileage I love the truck, the power it has is awsome and I have not hooked to anything that it didn't pull with ease.
Just wish I could get it to do better on light fuel mileage, but I like going fast.