Tune? Gears? Or Both!

[jblock285]

Ok, so here is the deal -- as you can see by my user name my truck is a dog. I have a 2007 sierra crew cab nnbs with the 4.8l and 3.23's. Dealer replaced the stock 17" wheels with factory 20's before I bought the truck. Gas mileage is ok but man its slow. I can't even chirp the tires around a corner lol. (and yes, thats with tc and st turned off). So do I really need to go to 3.73's or will a tune dramatically change the driveability? It has the HD trailering package but I don't ever tow anything, just want a quicker and more drivable truck. Thanks for the help!

[deyomatic]

Just for kicks, what diameter tire are you running? Are they considerably taller than the stockers that were on the 17" wheels? That will make a difference.

 

Also, on a side note, I've been seeing "NNBS" around, what is that?

[2007VictoryRed]

Just for kicks, what diameter tire are you running? Are they considerably taller than the stockers that were on the 17" wheels? That will make a difference.

 

Also, on a side note, I've been seeing "NNBS" around, what is that?

NNBS-New New Body Style

[takevin]

As said a million times before tune

[Spurshot]

Tune.

 

After that, if you still think it's a dog, you might consider gears, but you should consider how it might affect your gas mileage and whether that matters. If you're primarily a city driver on streets stop-n-go, gears won't change much mileage. Might even improve the stop-n-go mileage. Highway mileage will likely suffer with gears, depending on the ratio selected. Personally, I wouldn't bother changing from 3.23 to 3.73. I'd just go right to 4.10s if I were spending the money. 2wd or 4wd?

[jblock285]

deyomatic --- stock tire size was 245/70/17 and now i have 275/55/20's so there is about an inch and a half difference between stock and now.

 

spurshot - the truck is 2wd. highway mileage is good, about 20-21mpg but the city is about 13. I do drive alot and mostly city so mileage is a concern to a certain extent. So since there is not a live tune in my area anytime soon I should just call Justin and get the standard tune? I'm just wonderingif by putting on the 20's it made it that much worse. All I know is that my 2003 sierra would smoke this truck and it had the 4.8l and 33's

[brims]

deyomatic --- stock tire size was 245/70/17 and now i have 275/55/20's so there is about an inch and a half difference between stock and now.

 

spurshot - the truck is 2wd. highway mileage is good, about 20-21mpg but the city is about 13. I do drive alot and mostly city so mileage is a concern to a certain extent. So since there is not a live tune in my area anytime soon I should just call Justin and get the standard tune? I'm just wonderingif by putting on the 20's it made it that much worse. All I know is that my 2003 sierra would smoke this truck and it had the 4.8l and 33's

 

It costs a little more but it's pretty much the same as a live tune, the scan cable tune allows for Justin to tune your truck's character.

[Spurshot]

I think Justin is doing data-logging tuning now. Shoot him an email and see what he suggests.

 

Taller tires are horsepower robbers. Not only do they act like taller gears, they take more horsepower to turn.