L99 Engine With 6L80 Automatic Transmission

L99 6.2L V-8
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It may appear a whole heck of a lot like an LS3 at first glance, and your eyes are not deceiving you: the similarities are more than substantial. But look closely and you'll catch the traits that set the L99 apart. Visible are the exhaust valve reliefs, cam phaser system, and AFM components. --->

Camaro SS buyers who wish not shift their own tranny will get the only truly new engine in the Camaro lineup: the L99. This mill's similarities with the other Camaro V-8 are extensive: for example, its block, cylinder heads, crankshaft, and connecting rods-along with the intake manifold and throttle body-are all shared with the LS3. That said, there are some exciting additions that make the L99 best thought of as a "higher-tech" LS3; namely, Active Fuel Management and Variable Valve Timing.

Most readers are probably familiar with the functioning of AFM (formerly known as DOD, or Displacement On Demand). A quick refresher: under light-load conditions, the lifters on four of the cylinders deactivate and cease transmitting the cam lobe profiles to their valves, meaning the valves on those cylinders stay closed, reducing pumping losses (obviously, fuel is also cut to those cylinders). They do this upon receiving an oil pressure signal from the so-called Lifter Oil Manifold Assembly seen here, used in lieu of a valley cover. This is actually a unit from a truck engine, but the L99's will be very similar. --->

"For the L99, we tried to put in some technology to maximize as much fuel economy as we could out of the vehicle," John Rydzewski told GMHTP. "This is really a nice package to do that because we didn't really have anything like an LS3 [in terms of power] that was AFM-equipped. AFM works great when you have a lot of power in a lighter-weight vehicle. In a truck, it has only so much effectiveness." Up to this point, the only LS-equipped car featuring AFM has been the Pontiac G8 GT: how effective AFM proves in the Camaro remains to be seen in the EPA rating, but regardless of how the cards fall, keep in mind that G8 tuners have been able to tweak additional mpg out of those cars by altering AFM-related parameters in the ECM!

Active Fuel Management is a welcome addition for the Camaro, but this begs the question: Why only the automatic? Couldn't engineers incorporate this technology into manual-equipped cars as well? "When switching from 8- to 4-cylinder mode (or vice versa), there are some transitions that you have to deal with," explains Rydzewski. "Typically, a good way to do this is by using a torque converter. The ability to control the slip of the torque converter [via the torque converter clutch] is a big enabler in getting good transitions. The whole thought behind having AFM is, you don't want to have interruptions; you want it as seamless as possible." In other words, GM doesn't want to repeat the mistakes made with the 1981 V-8-6-4 Cadillacs, which often exhibited noticeable hesitations when switching cylinder modes (hence the technology only being offered for one model year). Nevertheless, we were told AFM could be implemented on a manual, and that GM actually is looking into it. But because a manual transmission's clutch is a straight coupling (and one that is hydraulically actuated only by the driver), it is not as adept at damping the slight drivetrain vibrations that occur during AFM activation/deactivation. That said, we know this: all things being equal, the efficiency of a manual transmission is always better than an automatic, so it will be interesting to see whether the L99 or LS3 achieves higher EPA numbers (one also needs to factor in the automatic car's 3.27 rear and 0.67 sixth-gear ratio versus the manual car's 3.45 rear and 0.57 sixth).