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The LS3 cam gear looks like something you would expect to see, but the L99 looks much different. It's obviously more than just a timing chain cam sprocket. Wonder if that is something to do with the AFM system ??????
Also look at the top of the L99's Pistons Compared to the LS3.


L99 = Automatic






LS3 = Manual

 

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I'm guessing the cam gear is for VVT.

The valve reliefs in the pistons are probably also VVT related. only 1 is 'funtional', which allows the piston to be installed in either orientation.
 

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The L99 and LS3 are two different motors. The l99 has the active fuel mangerment on it and the ls3 does not. The l99 is a more fuel efficent engine then the ls3 and its getting mated with the auto since the auto is not as efficent as a manual.
 

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very little difference how is there a 30hp difference?
did they tune it differently or what
or are they just saying that?
there are probably 100 threads on this :rolleyes:

AFM turns off 4 cylinders and on those 4 the cam profiles are less agressive. that is where most of the difference is going to come from.
also, its a 22hp difference.
 

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there are probably 100 threads on this :rolleyes:

AFM turns off 4 cylinders and on those 4 the cam profiles are less agressive. that is where most of the difference is going to come from.
also, its a 22hp difference.
Nope! The cam profiles are not different for the cylinders utilizing the AFM, otherwise there would be an imbalance with the motor in 'V8' mode. All the cam lobes (intake/exhaust respectively) on the L99 are the same. The difference in HP is due to the slight variations in piston surface shape (valve reliefs on the L99) and lift due to the different lifters between the LS3 and L99.
 

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Nope! The cam profiles are not different for the cylinders utilizing the AFM, otherwise there would be an imbalance with the motor in 'V8' mode. All the cam lobes (intake/exhaust respectively) on the L99 are the same. The difference in HP is due to the slight variations in piston surface shape (valve reliefs on the L99) and lift due to the different lifters between the LS3 and L99.
WRONG

http://media.gm.com/us/gm/en/technology/current_technology/fuel_economy/AtvFuelMgt.html
 

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I STAND CORRECTED.:rolleyes:

My experience with multi-displacement type engines is solely with Chrysler vehicles which do not utilize different cam lobe profiles for the inactive cylinders. The operation of the collapsible lifters is the same principle, though.

For those curious, here is the section of the article 383SS provided mentioning the cam lobes being different:
The valve lifters have inner and outer bodies, which normally operate as a single unit. When the engine controller determines cylinder deactivation conditions are optimal, the outer body moves independently of the inner body on the disabled cylinders' lifters. The outer body moves in conjunction with camshaft actuation, but the inner body does not move, holding the pushrod in place. This prevents the pushrod from actuating the valve, thereby halting the combustion process. Solenoids in the engine lifter valley operate to deliver high-pressure oil to the switching lifters, activating a release pin to separate the inner and outer bodies. Oil circulation and pressure do not vary, regardless of the engine's operational mode. Lifter design and pushrod length are the same for every cylinder, but camshaft lobe profiles differ for cylinders designated to be deactivated.
 

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there are probably 100 threads on this :rolleyes:

AFM turns off 4 cylinders and on those 4 the cam profiles are less agressive. that is where most of the difference is going to come from.
also, its a 22hp difference.
I tis usually a waste of your time explaining ANYTHING to him; he will just argue.

But if you want to know how much the Camaro is going to cost or when it is coming out, he is the man to talk to! :eek::lol:
 

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I found these hi res versions of the original images in the first post. I love the illustrations from David Kimble.
Does he do any illustrations like those of Jessica Alba in an evening gown, by any chance? :D
 
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