Why the two different engines in the SS?

[mikeyg36]

Originally Posted by SSGUNNER

Does doing an LS3 convert require a tune?

Yes

[Jrichards73]

my auto has a 3.91 final drive and let me tell you, its aggressive

[angie7]

I put a tune on my L99 to kill that awful AFM. I would've paid the gas guzzler tax when I bought it to have the LS3 and avoid AFM all together

[axis]

While no one really likes the AFM aspect of the L99, the VVT aspect is HIGHLY advantageous. Who wouldn't want a broader tq range.

[Rocky1974]

Originally Posted by RollaMo

To meet government CAFE standards.

There is no technical reason to have two different engines.
As mentioned, they used the LS3 with both auto and manual in the Corvette.

But the Camaro is a MUCH higher production volume car, and that would have affected the corporate average.

In the real world driving, an individual would not notice the very slight difference in fuel economy.
But in the fuel economy testing these cars have to go through, it makes a difference.

The Vettes are also MUCH lighter, more aerodynamic, and have much taller rear gears. I have a buddy who has an '09 Vette, LS3 Auto. It has 2.56 rear gears and will get over 30 mpg on the highway.

GM never did a AFM stick shift version of the LS engines. The 2014 Vette is the first time GM has mated an AFM engine with a manual transmission. If they had that technology in 2009, we would've probably had L99 manuals.

[Rocky1974]

Originally Posted by hrpiii

the L99 is basically an LS3 with the AFM/DOD mods on the internals. You can easily convert the L99 to the LS3 and keep the auto. It's really not "two" different engines because what ever mods you can do to the Manual, you can do to the Auto.

There's more differences than just the things that normally get changed when doing a "LS3 conversion". The valley cover, oil pump, timing gears, timing chain, camshaft, lifters, valves, valve springs, and pistons are all different.

[Rocky1974]

Originally Posted by Angrybird 12

Wouldn't you need to also change the ECM and wiring harness?

I think that the ECM's are the same. The wiring harness is different, but I think they just tie back a couple of unused connectors. Maybe somebody who's actually done it can chime in and tell us exactly what's involved.

[Rocky1974]

Originally Posted by not

26HP is next to nothing between the two and the A6 gearing is a bit more aggressive I think.....but M6 gets 3.45 and A6 gets 3.27 final gears.

I don't drag race but my buds who do........the ones with automatics anyways, state the A6 will beat an M6 in the quarter-mile.....

Okay, open up the floodgates on this one..

It's more than 26 hp by the time it gets to the wheels. The automatic transmission saps some more of that and it ends up being more like 40-50 at the wheels.

The automatics are better for drag racing. A torque converter is a wonderful thing to have on a drag strip. They drastically reduce the shock loads on the drive line which translate into quicker more consistent launches and the launch is everything. A stick has the potential to be faster, but it takes an extremely talented driver to beat an automatic at the track.