The cylinder heads on the 6.2L V-8 were the most notable improvement over the outgoing Corvette (6.0L LS2) engine. Although the cathedral port used on the LS2, as well as all Gen III applications, excelled in the area of port velocity, it simply couldn’t compete with the LS3’s larger, rectangular port for overall flow and power potential. Out of the box these cylinder heads flowed more than 300 cfm (at .600-inch lift), something previously unachievable without CNC porting. In essence the LS3 heads were a more cost-effective version of the LS7 heads, which has its origins in the C5R program, and a higher performance version of the L92 and L76.
Massive 2.165-inch intake valves took advantage of LS3’s larger 4.065-inch bore and used a hollow stem, a necessity given the size and RPM. The exhaust runner also changed from an oval to a more traditional D-shape, and used a 1.59-inch stainless steel valve. In stock form, these formidable heads supported more than 600 hp naturally aspirated and more than 1,000 with forced induction.
The LS3 found in the 2010–2015 Camaro SS shares many similarities with other Gen III/IV LS series engines. An aluminum alloy block uses ductile iron cylinder liners and six-bolt iron main caps. The block’s deep skirts that house the main caps make for an extremely sturdy bottom end far superior to the Gen I/II two-and four-bolt designs. It only needs reinforcement in the most extreme of applications (more than 2,000 hp). This deep skirt required moving the oil pump to the front of the crank. The factory crankshaft is made of nodular iron with undercut and rolled fillets, which is another sturdy piece capable of more than 1,000 hp.
The powdered-metal connecting rods are another story. Although far stronger than those in Gen I/II engines, they give up the ghost with a little bit of detonation in a forced-induction application. The same could be said of the hypereutectic aluminum pistons. Naturally aspirated builds typically only have to worry about a connecting rod bolt failure. The factory Multi-Layer Steel (MLS) head gaskets are sturdy enough for most applications, as is the arrangement of the four head bolts per cylinder. High-quality, reusable gaskets are used throughout the engine.
Like the SS, the LS and LT came with two 6-speed options: the 6L50 automatic and the Aisin Warner AY6 manual.
The electronics are one of the most notable differences between Gen III and Gen IV engines. Like all LS engines, the LS3 is topped with an individual coil ignition system, mounted on the valvecovers. The coils are revised from previous versions. The Mass Airflow (MAF) sensor is another improvement, switching to a slot-style with much better range. The coils, MAF sensor, MAP sensor (located at the back of the intake manifold), Intake Air Temperature (IAT) sensor (in the air box), cam sensor (in the timing cover), 42 lbs/hr fuel injectors, and four oxygen sensors (fore and aft of the catalytic converters) are just a few of the inputs to the E38 computer (also used with the L99 and LS7).
The 6.2L L99, which uses the LS3 as a foundation, was created specifically for the 2010 Camaro SS and is unique to the brand. The L99 adapted the VVT and AFM systems used on other LS applications as early as 2006. GM’s VVT is the first pushrod application to go into production and uses a phaser that is integrated with the cam sprocket and mounts to the front of the camshaft behind the timing cover. A large single “bolt” retains the camshaft and acts as a valve for controlling oil and telling the phaser how far to advance or retard the timing (up to 52 degrees).
The valve works off pulse-width modulation; when no pressure is present, it is locked and the cam is fully advanced. The camshaft itself has holes in the barrel to help channel this oil to the phaser. This technology is not only effective in boosting power “under the curve,” but in working with AFM to improve fuel economy.
Many thought this engine cover was too plain; Chevrolet dealerships later offered color-matched versions for an upcharge. Both the V-6 and V-8 used a similar air-intake arrangement with a sealed box and flat filter. Also notice the ECM and fuse box to the left, but no battery. All Camaros have the battery mounted in the trunk.
This is an exploded view of the Camaro ZL1’s LSA, which was released to celebrate its many improvements over the LS3, including the Eaton TVS 1900 supercharger. The long-block was identical to the Cadillac CTS-V’s with rotocast cylinder heads, reinforced block, forged connecting rods, and crank. The supercharger lid and intercooler were a considerable improvement over the V, hence its higher horsepower rating (556 versus 580 hp).
The ZL1’s LSA uses a similar accessory drive system as the LS3 and L99, making it a fairly easy swap if not for the ECM.
This air-box appears no different than the one on the SS as well, which is perhaps why the aftermarket has had such luck improving upon it.
The 3.6L LFX replaced the LLT V-6 for 2013, which boasted a number of improvements throughout. Most notably, the exhaust manifolds were cast into the cylinder heads, the intake port was reshaped, larger intake valves were used, and longer duration camshafts were added.
All in all, the LFX was lighter and more powerful than the LLT.
AFM has its roots in the 1981 Cadillac L62’s “V8-6-4.” A unique set of lifters deactivates four cylinders (preventing the valves from opening) under light-load conditions that are also controlled by oil, which comes from solenoids mounted in the valley cover.
Side by side, the LS3 and L99 vary in only a handful of areas. As mentioned, the L99 uses a separate set of lifters (for AFM) and a valley cover. The timing cover with its unique sensors, the timing set with the cam phaser, the cam “bolt,” and the camshaft itself are also unique to the L99. One downside to the AFM and VVT system is that it limits the amount of cam lift. The L99 cam specs .499/.499-inch lift on the non-active AFM cylinders and .510/.510-inch lift on the active AFM cylinders. Duration is a mild 198/201 at .050.
Because piston-to-valve clearance is a concern with VVT, Chevrolet also increased the combustion chambers on the L99 heads to 70 cc (from 68 cc on the LS3). This effectively brings the compression ratio from 10.7 to 10.4:1. The more conservative cam specs and compression limit the L99 to 6,200-rpm redline, while moving peak torque to 4,300 rpm (from 4,600 rpm). As the result, solid intake valves are used instead of hollow-stems to cut cost.
Whereas the L99 added technology to the basic LS3 design for greater fuel economy, the 2012–2015 Camaro ZL1’s 6.2L LSA V-8 adds strength to the LS3 architecture to stand up to the Eaton TVS 1.9L supercharger. Starting with the block, the bulkheads were strengthened by 20 percent while also enlarging the windows to enhance bay-to-bay breathing and decrease pumping loss. The block is made of 319-T5 aluminum with cast-iron cylinder liners (cast into place) that are actually machined with a deck plate.
Although the pistons are still (high-silicon alloy) hypereutectic aluminum, they are dished for proper air/fuel mixture and a 9:1 compression. The top ring land is anodized to deflect heat, and the piston skirt is coated to prevent cylinder wall scuffing. The floating wrist pin also contributes to a quiet and durable piston, as does oil-spray cooling. The LS9 is the only other LS engine to use these jets to pressurize