hey all im new here and wanted to give out some data that i wish i couldve found when researching what i wanted out of my ride

my main concern was how the driveability would be affected without swapping gears ($700)

first off i started out with an 09 5.3 flex LTZ crew cab 2WD

i went with a fabtech 6" lift with toyo 35's and 20" rockstar wheels

i drove around for about a month with a 3.08 rear end

driving around town was actually not that bad, and other than the occasional early upshift to where i had to immediately press the gas down to drop gears, i had no complaints. at 50 mph i got 24mpg

the highway was a completely different story, i could only manage 12mpg at 65mph in 5th gear. if i was in 6th gear i would only get 10-11 mpg (keep in mind this is on very flat florida highway)

towing my 22' bay boat i could manage 11 mpg at 50 mph and 8 mpg at 55 mph and acceleration around town while towing the boat demanded the use of the manual shift button because the tow mode would run the rpms all the way to and sometimes in excess of 4000. the manual shift allowed me to let the rpms climb without going overboard and wasnt a big deal until i got to the highway where i had to stay in 4th gear, limiting my top speed to 60mph. anything in excess of this i got 8mpg and less. my boat and trailer are between 4000-4500 depending on fuel level, gear, ice.

i debated hard between 4.10 and 4.56 gears and went with 4.10 after finding a post on another forum about a guy with the same set up getting near stock mpg numbers from the 4.10s.

4.10s installed for $700. aftermarket gears, they click a little under deceleration and required a break in period in which i could not travel more than 10 miles at a time without resting the vehicle for atleast 15 minutes. this was required for the first 200 miles, and no towing for the first 300 miles and at 500 miles i had to get my gear lube changed. just FYI

acceleration felt stronger throughout the power band, highway passing power impressive here were my numbers

50 mph 24 mpg
60 mph 22 mpg
65 mph 20-21mpg
70 mph 18 mpg
i averaged 16mpg with a 70% city and 30% highway

towing my boat was improved a lot. i no longer needed tow mode or manual shift, power felt pretty close to stock.

now i just ordered my hypertech max energy programmer and went with the premium tune because i felt like the mpg numbers while driving were too volatile on the mpg gauge and the motor never switched down to V-4 so i was hoping the programmer would at least pull the tires and gears together for more efficiency.

i chose the premium tune first because i normally use 87 and if i dont notice any difference with premium i doubt ill notice one with the 87 tune.

anyways shifting feels perfectly stock and a lot smoother than before the programmer, the rpms climb very smoothly and i notice the mpg gauge reading more consistent flow numbers, alot like when the vehicle was stock and it now switches to V-4 when pedal pressure is light, just like stock.

mpg numbers are similar but improved slightly.

50 mph 28mpg
60 mph 24mpg
65 mph 22 mpg

i havent taken it on the interstate yet so i cant comment on 70 mph + nor can i comment on the towing power yet.

the full tank to empty mileage are as follows
stock 400-410 miles
with lift, no gears, no program 200-220 miles
lift, gears, no program 270-290 miles

as soon as i run this tank out ill let you know what the range is.

also to note i have NO "performance" mods like air intake or exhaust because the money i would spend on these i could afford $400 in gas and the benefit wouldnt be realized for years even with a 2 mpg advantage. the only reason why i got the programmer was to tie together the gears to the lift and to adjust the speedometer, if theres a performance gain, ill notice it as soon as i hook up the boat but its not expected.

in this instance i DO expect a mileage increase because the gears were swapped. NORMALLY i think programmers are junk for stock trucks unless they are diesel motors, in which case the results can be night and day.

im not bashing them, but i really think that if GM could spend 5 minutes reprogramming their ECU's to get better mileage and better performance, they wouldve had it covered especially when competition is as stiff as it is in the full size truck world.

im open to opinions but not bashing, and my opinion is subject to change as i drive with the new tune.

the main point i wanted to make was what a difference the gear swap made and give some info for those who are considering a lift and wheel upgrade. any questions feel free to ask

ill post some pics soon and will update as i continue to drive the truck

 

pics added to the show your ride section

 

Thanks for the info. Very valuable and I'm sure many will find it helpful

 

I've been considering this recently, so perfect timing. My truck has the 3.08 in it and I know a 6" lift with 35" tires will kill it. Also considered between 4.10 and 4.56. Just trying not to spend such a large amount of money at once. Maybe even throwing in a 4.10 without the lift just to have. I get 270-290 a tank stock. I'll definitely consider buying the programmer if I lift it.

 

Were you able to adjust the speedometer for the tire size increase? I have a 2007 (bought used) with larger tires and the dealer tells me there isn't anything they can do. They can adjust to a different tire size that was available from the factory, but mine's diesel and there were no other sizes available that year.

What programmer did you get?

...Mike.

 

Hypertech Max energy. Yes it calibrates the speedo and also corrects for gear ratio adjustments

 

All sounds good but, I guess my question is....Why a 6" lift and 35s on a 2WD truck?

 

because its my daily driver and it tows my boat and it looks and feels sweet. ive owned 5 4x4s and never used 4 wheel drive except in the snow, now i live in florida. and if im going to the beach or going hunting or somewhere unusual i take my k5 to get banged up.

 

Fair enough, just askin'. I too, have recently moved to Florida (Pensacola) but still have my "Clorado Oriented" '09 Silverado 4x4. It will eventually go away, in favor of a CTS-V Coupe. Also, like you, I have a '91 K5, should I need 4WD at any time.

 

My only comment has to do with your feelings about the benefit of a "tune." Yes, GM, Ford, et al could program their trucks, cars, etc. for max milage. But vehicles come with a "rich" fuel setting from the factory because it is easier on the engine. A perfect stoichiometric setting is around 14.7:1. Factory settings can be as rich as 12:1. The reason tuning the chip has such dramatic benefits for most vehicles is that by going back to a ratio of around 14:1 we burn less fuel and improve the responsiveness of the vehicle at the same time. In addition, if your vehicle has an automatic transmission the factory usually sets the shift timing to be long and smooth. Many people prefer a more pronounced, shorter shift and the tune usually can accomplish this as well.
Best wishes.
Glen