nosaj

I was looking at the new camaro's yesterday and the dealer told me he could order one just like I want. I love the auto's with converters, the only thing is it has less hp, but my question is, what is the difference on the L99 cars other than the deactivation thing for fuel mileage. Does it have different heads, cam or anything like that?

rayhawk

It has the same heads, but a milder camshaft due to limitations of the AFM system. That is where the peak power is lost at. However, you do get VVT with it, which allows the motor to generate some extra mid range due to optimized valve timing. The fuel cutoff is 6200 for the L99 (A6) and 6600 for the LS3 (M6). The A6 car also gets much more agressive gearing from the factory, not in the rear but in the transmission itself.

GM advertises the LS3 at 12.9 @ 111, the L99 at 13.2 @ 105.

nosaj

Thanks for the information.

OrangeChevyII

The difference is in the heads.

Auto=10:4:1 compression
manuals=10:7:1

The heads on the auto's are the 6.0 truck head on the DOD motors. Smaller intake valves. Dont worry, the l92 valves are a little over kill. They perform just fine.

rayhawk

No, the heads are the same as the LS3. The L99 has slightly lower cr due to valve pockets cut into the pistons to accomodate the wide range of valve timing provided by the VVT.

ss1129

iTrader: (16)

^^^ what he said.

OrangeChevyII

Thats odd, I have all three motors at the shop and the 6.0 truck motor heads has the same casting numbers as the L99 motor.

JayplaySS

iTrader: (15)

The A6 is a great trans, though a trans tune does wonders but I sold my A6 H/C C6 and will be getting back into an M6. If you are not really worried about every ounce of power and performance, go for the A6 but realize that with only 105-107 traps (avg I'm guessing) unless you mod it, you could be beaten by SRT8's, LS1 F-bodies and even 370Z's, not to mention a few Mustangs here and there.

rayhawk

Here is a writeup from GMHTP where they mention that the L99 and LS3 use the same heads.

http://www.gmhightechperformance.com...nsmission.html

As for the casting number, aren't they all L92 castings, even for the latest 6.0 motors?

oshia86

My car should trap in that range and i pulled away from an srt8 300 with cai and predator tune when i was stock, also haven't had any problems with mustangs. Only got to go against 1 f body though, and that thing was wore out, and i took it pretty easily. Haven't touched a 370 yet though.