HP/MPG

[nonickatall]

Yeah no way a stock tranny is gonna hold 1000hp and not a chance a well worn/worn out 2004 rearend or frontend is gonna hold up either. The BW Tcase unit wont stand a chance at life either with a 1000hp engine twisting it up. OP better get his wallet out and atleast 5 credit cards.

Some like yo waste money that way.

I drove in my past a lot of cars, even a Ferrari Testarossa, which was not mine, as well a Porsche 911, a Mercedes E Class 500 and other. And I can tell you. After a while they all had a weak acceleration. Your needs increase with your possibilities.

Because i have my own garage and repair my cars, even automatic transmissions, myself. I now looking for a good drive feel, a good practicality, reliability and most important, easy to repair quality.

Thats why I landed at the gmt820...

And I admit, I love this car and would not treat it bad with a heavy gas foot. I hear and feel, because of my mechanical work, pistons, valve shaft, push rods and I drive carefully and relaxed. Probably that has do do with age.

Know i invest my energy and money on good time with family and sport to keep me healthy and not on acceleration witch brings you nowhere at the end of the day.

But i accept, that there are people who have a different view on that.

And as a German, I have to admit, I always get a little jealous looks at Americans who do crazy things with cars, like extreme wheels, hot rots, dragsters and so on.

Impossible in Germany, the car country, which is at the time, full of fear of clima change and the young generation hates cars, their country and everything, except internet. And the care about cultural appropriation, gender things and all that useless crazy stuff from internet..

 

[Marky Dissod]

Ich spreche nicht gut deutsch.
That said, some of us are aware that our Corporate Average Fuel Economy tests are based on anachronistic, unrealistic driving behavior-patterns that are much closer to hypermiliing than how normal people drive today in most places.

As a real-life example, NONE of the GMT800 vehicles of any kind should EVER have had 3.42 or lesser axles ...
based on how they are driven in real life.
But the unrealistic CAFE MpG test driving patterns are the only thing that explains 3.42 and lesser axle gearing.

Fact is many GMT800s would get better fuel economy if they had more assertive gearing:
3.73, 4.10, and even 4.30 should be FAR more common than they are.
The other payoff would be that 4L60Es would last longer between rebuilds.

In Europa I understand it works a bit differently, as y'all have government regulations which very strongly influence holding down the displacement of any engine's cylinders to 0.5L each.

 

[UnderDogg]

You can source new axle from a salvage yard or regear your existing differentials. If you pay someone to do it, it's about $3k depending on your market. The gear sets themselves are $250-800 per axle plus overhaul parts and labor or tools if you DIY.

What gears did a 2004 Yukon Denali come with? 3.73s?

I'm not sure. I believe it was just a stock suv. I bought it off of a guy who got it from his father in which he was the original buyer in 04 and its been kept up since then. When I got it there was alot to be done because it just had been sitting in the driveway for about 2 years.

 

[UnderDogg]

You can source new axle from a salvage yard or regear your existing differentials. If you pay someone to do it, it's about $3k depending on your market. The gear sets themselves are $250-800 per axle plus overhaul parts and labor or tools if you DIY.

What gears did a 2004 Yukon Denali come with? 3.73s?

Also thanks for chiming in with this info sharing your knowledge. It is very helpful. Myself and my uncle who's retired ticker around with our vehicles but when I bought this one it has been our biggest challenge. We haven't done all the work ourselves. I've had to put it in the shop for a few things but for the most part I try to do alot of things myself. I'll tell you one thing. My tool box has surely been improved. You be surprised about the things you're willing to buy to complete the project.

 

[S33k3r]

If you don't mind taking a picture of the codes in the glovebox, we might be able to tell you what gears you have. Also, you can write to GM and get a build sheet. Finally, 4.10 gears came stock in some of the GMT800s. I know for a fact they came in the Sierra Denalis.