'12 LT less HP than '07

[S1W99]

I bought an '07 LT about 7 months ago. I liked it so much. I moved up to an '12 LT. The '12 is noticeably weaker than the '07. Is there a reason for this? Is it gearing by chance?

Thanks

 

[Doubeleive]

shouldn't be weaker you did go from a 4 speed to a 6 speed though. diff ratio could be different as well you could have gone from a 3.42 to 3.08 or something of that nature
your rpo codes in the glove box will tell you. those are the kinds of things you probably should have been looking at when shopping around they make a difference.

 

[swathdiver]

I bought an '07 LT about 7 months ago. I liked it so much. I moved up to an '12 LT. The '12 is noticeably weaker than the '07. Is there a reason for this? Is it gearing by chance?

Thanks

What Wes said!

Your 2007 will have a 4-speed transmission and it might have 3.73 gears. The 2012 has a 6-speed gear box and it might have 3.08 or 3.42 gears.

In your gloveboxes are the RPO Sheets, a sticker on the door, look at the "G" codes.

GU4 = 3.08
GU5 = 3.23
GU6 = 3.42
GT4 = 3.73

Let's find out that before looking at anything else.

 

[91RS]

Your 2007 likely had 3.73 rear gears and I don't think you could get that any more with the 6 speed. The later ones feel more held back to me also, not sure if they did that for fuel economy or longevity of the driveline. Get a tune and it should help that feeling.

 

[Bill 1960]

I don’t entirely agree with the gearing theory, because a six speed has lower gears in first. But it really depends on the OP’s perception at this point, and we have no idea if he’s feeling this based on 0-60; 40-60; or track times LOL.

It may be nothing other than a perception based on a difference in throttle response. People buy throttle response tweaking devices all the time and convince themselves it’s improving performance when all it did was give them 80% of the output at 40% of the pedal.

OP, I suppose at this point the original truck is gone so you have no opportunity to run a comparison of the two with a stopwatch?

There are many things that can diminish performance.
And many things the previous owners of the ‘07 may have done to enhance it.

 

[intheburbs]

If the '12 has 3.08 gears, it's gonna be a dog, even with the 6-speed.

 

[Bill 1960]

Not likely.

3.73 x 3.059 = 11.41
3.08 x 4.03 = 12.41

Absent any torque management nanny interference.

My money is on tuning or lack of maintenance.

 

[swathdiver]

More Torque Management? I know the numbers with regards to gearing like Bill points out but we hear complaints all the time of how doggy 3.08s feel and nobody complains about 3.73s.

3.73s pin you back into your seat on the Sierra and she's lifted on 35s.

 

[Bill 1960]

Yeah, but do the math on 3.73 x 6L80 gearing. It’s all relative to an individual perception. Lacking any measurements all we have to rely on is the infamously unreliable butt dyno.

 

[swathdiver]

Yeah, but do the math on 3.73 x 6L80 gearing. It’s all relative to an individual perception. Lacking any measurements all we have to rely on is the infamously unreliable butt dyno.

Oh I have, it's awesome! Better than an Allison with 3.73s! I bought a VC-200 to do testing on the streets of Mexico and the first thing we did was test the Sierra's G-forces at launch.