I'm thinking about replacing my current 5.3 motor with LS3 6.2L . What has to be done with the computer for this set up to function with my truck. Thanks to GM great 07 flex fuel motor I'm burning almost 1.5 quarts of oil every 1000 miles. What I here from the dealership is that is normal for that motor to do that. Any gm mechanics know how I can get them to stand behind the motor?
I don't have experience with anything past LS2, but I suspect your 07 ECM would only need a tune to run an LS3. This assumes your 07 is drive-by-wire. Perhaps someone at ls1tech could give you more details. While the LS3 is undeniably nice, it will likely cost twice as much as a 6.0 LS2 and three times as much as a 5.7 LS1. Used LS3 are very rare unless you have a lucky connection.
I drove a 2008 Denali 4WD with the 6.2L Vortec. I wasn't all that impressed to be honest to go out of my way for one. Didn't have as much acceleration as I had anticipated at all. Felt about the same as the 5.3L to me in my cousin's Tahoe. I think the LS3 wouldn't have as much torque down low due to the car intake on it.
As mentioned above, both your 2007 5.3 (I assume LY5) and LS3 are Gen IV engines. As such, the ECU you have will work on the LS3 after flashing it with the appropriate tune.
Most defiantly the 5.3 in a suburban is slow. The 6.2 I'm looking at is rated at 430hp and 424 torque . I'm on the fence on weather or not to trade it in. So keeping the truck I could have a little fun waking it up. At least that is what Im thinking.
my DD is an 04 Suburban 5.3 AWD, and, while not a racecar, I would not describe it as slow - perhaps I'm geared lower than average but the thing pulls like a freight train