'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.

 

[S1W99]

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.

I don't see the G designations. Attaching both the '12 '07 glove box information in that order. Also, I use a Range adapter so it stays in V8 move. What is the "tune" option for gearing?
The 07 will pin you in your seat, the 12, nope. Mpg is about the same. 17.5 hwy on there '12. Would think mpg would be better on the 12.

Thanks!

 

[Fless]

GU4 and GU6.

 

[S1W99]

GU4 and GU6.


View attachment 356968
View attachment 356969

Ty sir

 

[S1W99]

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.

Tune?

 

[swathdiver]

Tune?

A tune is where a guy goes in and makes changes to the programming of the engine and transmission for better performance and durability based on what you want.

The older truck has 3.42s and the newer one 3.08s. The engine in the older truck does not have VVT, it runs a single pattern camshaft and to me anyway, they "feel" more powerful. Now get a BlackBear tune and put 3.73s in the 2012 and you'll think the 2007 is the old 2012! LOL

 

[S1W99]

A tune is where a guy goes in and makes changes to the programming of the engine and transmission for better performance and durability based on what you want.

The older truck has 3.42s and the newer one 3.08s. The engine in the older truck does not have VVT, it runs a single pattern camshaft and to me anyway, they "feel" more powerful. Now get a BlackBear tune and put 3.73s in the 2012 and you'll think the 2007 is the old 2012! LOL

Will this give any risk to hurting my engine at all? And where do you get this type of work done?

 

[George B]

One observation on my 13 is that prior to my BBP tune it would shift out of first into second really early and require quite a bit of pedal to drop down again. This early shift made it sluggish getting up to speed through the first part if second gear. I have 3:42s. Perhaps the 4L60 was staying in first longer.

Edit:
OP your truck is similar to mine. The shifting, torque management and throttle delay make them feel like a bit of a dog. Get a tune. It’s money well spent.

 

[swathdiver]

Will this give any risk to hurting my engine at all? And where do you get this type of work done?

Not unless you beat on it and don't take care of it, same for stock. The transmissions seem to last longer with the right tune. With a BlackBear tune for example, you buy a little computer from them, when it arrives you hook it up to your truck and record a data log. Then you hook that up to your PC, email the file to BlackBear and in a couple of weeks Justin will email you back a custom tune for the engine and transmission. Upload that to your truck and start driving. It'll get better as the truck learns.

 

[Geotrash]

Will this give any risk to hurting my engine at all? And where do you get this type of work done?

Just the opposite. For the transmission, a Black Bear tune tightens up the shift points so that it doesn't slip the clutches in the transmission like the factory tune does, thus extending their life. For the engine, they turn off the AFM system which avoids the costly problems that can come with that over time. And, they will tweak the fuel and ignition tables to optimize fuel and spark delivery to increase horsepower and torque.

The only downside is that you need to run premium fuel with it, although they can also tune it so it will still run 87 if you prefer, but you won't get as significant of power gains. As James says, they do this by selling you a datalogger/programmer that will read the current engine and transmission parameters while you drive a prescribed 20 minute cycle. Then you email the files it generates to Black Bear and they email you back two tune files a week or 2 later that you then apply with the device. Super simple. I also used them to set up my tune for a new cam, and they did a beautiful job.

I prefer their approach to a 'canned' tune, because it's a tune made specific to your vehicle and preferences, and not just generalized settings tweaks.

 

[George B]

Just the opposite. For the transmission, a Black Bear tune tightens up the shift points so that it doesn't slip the clutches in the transmission like the factory tune does, thus extending their life. For the engine, they turn off the AFM system which avoids the costly problems that can come with that over time. And, they will tweak the fuel and ignition tables to optimize fuel and spark delivery to increase horsepower and torque.

The only downside is that you need to run premium fuel with it, although they can also tune it so it will still run 87 if you prefer, but you won't get as significant of power gains. As James says, they do this by selling you a datalogger/programmer that will read the current engine and transmission parameters while you drive a prescribed 20 minute cycle. Then you email the files it generates to Black Bear and they email you back a tune file a week or 2 later that you then apply with the device. Super simple. I also used them to set up my tune for a new cam, and they did a beautiful job.

I prefer their approach to a 'canned' tune, because it's a tune made specific to your vehicle and preferences, and not just generalized settings tweaks.

I received two tune files. One for 89 and one for 92 octane.