My Duramax has been running a lot stronger these last couple of weeks. 9100 miles. I have not said anything to anybody just in case I was full of it. Now I am sure it is stronger. I called Steve Cole to see if he did something ( he plays with the truck sometimes) and he said no. I was convinced after last night blowing away a Heemi with my 30 hp baby program.:ro) (Thats all Steve will give me):h ) Some of you guys have talked about the truck getting stronger at about my mileage and now I am a believer. Have I mentioned that I love this truck?:cool:

mike

My increase in power and mileage came between 10 and 15k so the best is yet to come!

I love mine too.:ro)

Blake

Mike If You Think That Is Awsome You Should Try Burning Dyed Fuel----------its A High You Cannt Understand

It felt like the motor loosened up at about 10K miles for me..........:D

Although I was running a Juice at 7K miles might have helped it break in faster........

It will definately get better with time.

T:cool: NY

I feel like mine got stronger at 10K. I know that I started to see better fuel mileage at that time also...Might all be in the mind, you never know..

My truck has a little over 10K miles and I have not seen any change in performance or fuel milage since new. I have read many posts reporting improvements from 6K on up. There have also been some posts like mine reporting no change. Any ideas as to why some trucks have peformance changes after gaining some miles and some do not?

The good new for me is I have been happy with the way my truck runs since day one.

You are probably too easy on it BH. :) I am definately getting better fuel mileage but I am only at about 7k. I really didn't expect and improvement and to be honest I thought it was all BS. I even think it runs a little stronger but that could be my imagination.

The colder, denser fall air charge has more 02 for detonation, and a ton more cooling capacity through the CAC, making charge air much denser than in summer. The diff with just 20 degrees ambient is visceral to me.

We are also being blended down for winter fuel now and I still notice a fuel mileage improvemtent. There is more to it then just cool air.

Oh pshaw!

Air is everything. Density altitude more accurately. 20-30% of your HP comes and goes with it. But seasonal changes are so gradual it's hard to notice it happening.

Not demeaning the break-in phenomena, but it is dwarfed by density altitude changes.

I don't think Socal has a winter blend btw, but I don't know for sure.

5555 miles today so sometime soon, well sometime in the next 3 months, perhaps I will feel this added power. Has a lot of power to start with though so I'll be happy with what I have until I get a programmer.;)

Maybe someone should hold the Duramax out the side window and do some tests and report.):h I vote for mesquito2 to do the tests.:D (sorry, spellcheck keeps quiting on me)

mike

masterp2, if you really think that break-in can't make a huge difference, I think you should go back and re-evaluate. . . It does. . .

Where did I say that?

You pretty much implied as much here. . . .

Oh pshaw!


Air is everything. Density altitude more accurately. 20-30% of your HP comes and goes with it. But seasonal changes are so gradual it's hard to notice it happening.

Not demeaning the break-in phenomena, but it is dwarfed by density altitude changes.

I don't think Socal has a winter blend btw, but I don't know for sure.

If you didn't mean to imply that, then I retract my statement. . . .

It's ok, just suggesting that other things play into the perception of increased power. I agree that break-in makes a difference, it's not very debatable.

Here in dry air hell, the diff between the 115 F 40% day and the 50 degree, 8% one is like having an extra 4 cyl motor under there. The timing of this post is what drove my statement, just in the last month we dropped 20 degrees daily high, and it is felt in my truck.

I wonder if GM has a break in program in place until a certain odometer reading and then switches to another more powerful version after they feel the engine has a certain amount of time on it.
Thing that make you go Hmmmmmmmmmmmm.

I think your on to something guy..........;)

you know we need more "smilie" these suck!

:D :D :D :D :D :D :D :D :D :D :D :D :D :D :cool:

On the subject of break in miles... I have a funny story to tell...

Last Fall we had a guy bring in his 03 Montana, had about 5000 miles on it and he said that recently he noticed that the level ride was operating more frequently lately...
I inspected it and everything worked as designed, didnt notice any fault and as compared to any other Montana, it was good to go. Customer didnt buy it, swore it was acting up. I then explained to the customer that the Electronic Level Control system is calibrated to do this after a certain mileage to allow for the suspension components to be fully seated.. Now that they are broken in and seated, the system will operate normally. I then told him that his previous operation of the system was actually the abnormal and now its working like its supposed too.. I must have made that BS sound very convincing because he bought it hook/line and sinker...