Upgrading the LS2, L76, LFA, and LZ1 Engines

The aluminum block 6.0L engines are light weight and fall between the 5.3L and 6.2L in terms of power and durability. On a stock engine, the following upgrades can improve performance and fuel economy:

• A Cold Air Intake Kit
• Headers
• An Aftermarket Exhaust
• A Computer Programmer

Below are more upgrades that will improve the performance of the LS2, L76, LFA, and LZ1 engines.

Engine Block

These engines share a 4.000 in. bore diameter. The cylinder walls are thinner than a 5.3L, but thicker than a 6.2L. This means they can handle more boost than the 6.2L engines. The cylinders can be bored to 4.030 in. However, we recommended leaving them as thick as possible when running boost. When bored and stroked, displacement can be as high as 408 c.i.d. (6.7L).

When stroking, choose a piston with minimal skirt taper. This prevents the piston from rocking at BDC and scraping up the skirts.

Rotating Assembly

The stock pistons are a known weak point. They will crack in high horsepower engines. A set of Forged Pistons should be high on your priority list.

Gen. 4 rods are stronger than the Gen. 3's and have full floating pins. They can handle about 800 hp. and 6,500 rpm in boosted applications. If you're getting forged pistons, upgrade to Forged Connecting Rods at the same time.

Even though it’s cast, the crankshaft can handle about 900 hp. and 7,000 rpm (for a limited time). A broken crankshaft is bad news. Upgrading to a Forged Crank early in your build will save you the headache later. When you upgrade, a 4.000 in. stroke crankshaft costs about the same and increases displacement.

The chart below lists standard specs compared to common performance Rotating Assemblies.

Cylinder Heads

The LS2, LFA, and LZ1 have cathedral port cylinder heads can be CNC ported for more airflow. The heads can be milled for more compression. However, compression on these engines is already in the high 10:1 range. You don't want to go much higher when running pump gas. For high rpm engines (7,000+), LS3 intake valves are lighter and can be cut to fit.

The L76 heads have rectangle intake ports, like the LS3/L92 heads. Light weight, hollow stem intake valves from the LS3 drop right in for high rpm use. They can be CNC ported for better air flow. It is also common to mill them up to 0.030 in. to increase compression.

There are many Aftermarket Heads available. The heads flow better and have thicker decks to maintain head gasket seal. A wide range of runner and chamber volumes are available. Some also go from a 15 degree to a 13.5 degree valve angle for even more power.

A 4-Corner Steam Kit is another smart upgrade. It reduces hot spots in cylinder #7 that cause the piston rings to butt and crack the piston.

Camshaft and Valvetrain

LS engines respond well to Cam Swaps. In addition to valve springs and rockers, the cam needs to match the compression, torque converter, rear-end gears, etc. Keep in mind, piston-to-valve clearance is tight with cams over 230° duration @ 0.050 in.

Spring Kits are available for typical 0.600 in. lift cam upgrades. Titanium retainers are another upgrade that will reduce

The trunnion bearings in the stock rocker arms are another known weak point. A Trunnion Upgrade Kit should be installed when you upgrade the valvetrain. Upgrading to Full Roller Rockers is another option.

The stock rockers are pedestal mounted. High spring pressure (over 475 lbs.) can pull the bolts out of the cylinder head. Converting to roller rockers and stud mounts is recommended for cams over 0.600 in. lift.

The L76, LFA, and LZ1 are equipped with Active Fuel Management (AFM). It's good for gas mileage, but not high performance. If the valvetrain is in good condition, an AFM Disabler can turn the AFM off. When upgrading to a performance cam, an AFM Delete Kit is strongly recommended. These kits replace all the AFM components with standard parts.

Piston-to-Valve clearance and high spring pressure (over 400 lbs.) can be a problem with the Variable Valve Timing (VVT) used on the L76, LFA, and LZ1. Some aftermarket street cams require the use of a Phaser Limiter. A VVT Delete Kit is a better option for larger street/strip and race cams. A VVT delete kit will completely remove the VVT components.

Intake Manifold and Throttle Body

Porting is a popular option for stock truck-style intake manifolds. When you swap one of these engines into a car, we recommend using an Aftermarket Intake. Just be sure to match the intake port shape on the heads.

At 87mm, the factory 4-bolt throttle body is fairly large and won't be a restriction in most applications. Most aftermarket intakes are designed to accommodate larger 92mm or 102mm Throttle Bodies.

Fuel System and Tuning

Upgrading to larger Fuel Injectors is often needed to meet the demand of increased power. The factory fuel pump will become a limitation around 400 hp. So, plan on upgrading the Fuel Pump as well.

Truck engines have a conservative tune from the factory. Tuning the computer changes the fuel and ignition curves to increase performance. Plug-In Programmers are easy to use, but they do have limits. Custom tuning requires more knowledge, but will provide even better performance.