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HI, I just bought a 2009 Silverado crew cab with a 4.8L.

I have 35's with stock gears. The RPM is low, I drive 65MPH at 1500RPM. but when driving on a upgrade, I down shifts a lot.

Some people tell me to go with 4.11, others with 4.56.

I would like to get the best gas mileage and performance possible.

 

Please let me know what to go with and the good and bad of the gears.

 

Thanks.

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4.56 is "optimum" RPM range for 35's.

 

Im gonna say its a 6 speed because 09 is the first year they put in the 6L80E's.

 

And like Chris said, depends on where you do most of your driving: highway, or backroads? 4.56 better for stop and go, 4.10 for highway

 

Check out this website for calculating your RPM's:

 

http://www.novak-adapt.com/knowledge/gearing.htm

 

On your tranny, your 6th gear (which is a second overdrive) has a ratio of 0.67

 

Found the ratios on this website:

 

http://6l80e.com/

 

Let us know if you have anymore questions

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Its a 4.8 so its just a 60e not that it really matters when it comes to this. 4.56 minimum.... a 4.8 needs all the help it can get as far as mechanical advantage goes. You could even go 4.88 to be honest. 4.56 nets you a 2000 rpm cruise at 65 mph.... nothing to worry about. 4.88 is still only 2100 rpm. Do not fear putting in some gears. Before people start spouting about mileage.... um the 35's and lift negate all that... because that is usually the first thing I read. Both my trucks tach higher than the 4.88's would and my tires and gears are oem...

Sent from my SGH-I747M using Tapatalk 2

 

 

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My truck does not have the 6 speed transmission. its the LT..., not to many accessories on it.

 

I do both city and HWY driving. I currently get 18MPG avg with an EDGE EVOLUTION CTS Programmer I purchased.

 

Thanks for the tips, everything helps out.

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My truck does not have the 6 speed transmission. its the LT..., not to many accessories on it.

 

I do both city and HWY driving. I currently get 18MPG avg with an EDGE EVOLUTION CTS Programmer I purchased.

 

Thanks for the tips, everything helps out.

 

Lmao. There's not a snowballs chance you're getting 18mpg.

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I know its hard to believe I get the 18MPG. I entered the info the programmer asked for...(stock gears, 35" tires) and I have it set to the economy setting. I don't feel a lot of power when I floor the gas pedal, but the economy is there. I also have a k&n drop in filter. don't know if the filter helps or not.



I was told at OFF ROAD WAREHOUSE that once I change the gears.... I should get better performance and economy. is this true??


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Better performance yes...better mpg...maybe. I will bet you the title to my truck you aren't getting 18 mpg. I barely saw that type of mpg stock. The day I put a 33x12.50 on 13 mpg was a dream to see.

 

How are you calculating said mileage?

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The programmer I have installed calculates it for me. (EDGE EVOLUTION CTS) it did improve my gas mileage since I got it, I entered the info it asked for (tire size, and gear ratio) and it calibrated my odometer. I checked it with a gps and my brother driving behind me comparing speeds on cruise control.

 

I also checked it manually... I filled up the gas tank, and when I refilled the tank, I divided the miles driven by the number of gallons to fill it up.

 

I don't let my tank go under 1/4, last fill up 19 gallons and I drove 353 miles.... 353/19=18.5789. I also don't drive my truck hard, I take it easy with the gas peddle...

 

I have no reason to make this up, I want to get the best mileage possible and having the aggressive look with oversize tires.

 

I highly recommend the programmer, It does help on mileage. I paid a little over $600. like they say, you get what you pay for.

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My truck does not have the 6 speed transmission. its the LT..., not to many accessories on it.

 

I do both city and HWY driving. I currently get 18MPG avg with an EDGE EVOLUTION CTS Programmer I purchased.

 

Thanks for the tips, everything helps out.

*facepalm*

 

Let us gather my friends, so we can talk about a lifted truck, performance and MPG in the same thread AGAIN.

 

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post-65833-137345907073_thumb.jpg

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