[Editor’s Note: This LS2 engine upgrade guide is part of a series of LS engine upgrade guides assembled by a team of LS experts at Summit Racing that we are sharing at OnAllCylinders. The LS2 is noteworthy within the LS engine family in that it appeared in both cars and trucks (as did the L76). The car and truck versions of the LS2 came with different accessory drives, intake manifolds, and oil pans. They also had different VIN codes. The engine is a Gen IV, 6.0L aluminum-block V8 that first appeared as the base engine for the 2005 Chevrolet Corvette C6. It also powered the 2005 Pontiac GTO, 2006 CTS-V, and Holden Monaro. The truck version powered the TrailBlazer SS, SSR, and Saab 9-7X Aero. This article will focus on the car version. For a primer on the LS engine universe, read LS Engines 101: An Introductory Overview of the Gen III/IV LS Engine Family.]
Intro to LS2 Car Engine Upgrades
On a stock LS2 car engine, the following upgrades can improve performance and fuel economy:
[Every engine spec you’ll need for an LS2 car project can be found here: LS2 Car Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More.]
How to Tell the Difference Between LS2 and Other Engines
At first glance, the LS2 car engine looks similar to other engines. The easiest way to tell them apart is to check the 8th digit of the VIN code.
If you don’t have the VIN, you will need to look much closer. Learn How to Identify an LS Engine here.
If you have an LS2 and are on the hunt for the best mods, you’re in the right place. Here’s the roadmap to upgrading your LS2 powerplant for maximum performance.
(Summit Racing’s Paul Spurlock contributed to this article.)
Upgrading the LS2 Car Engine 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 inch. Cars typically run cams in the high 220s, while trucks are usually between 208 and 215 degrees on the intake.
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. The stock rockers are pedestal mounted and are good for .600 lift. About 175-pound seat and 450 pounds of open spring pressure is the limit for street-driven hydraulic roller cams. If you want to run more lift, plan on upgrading to full roller rockers.
If you have a 2007-or-later LS2, you can convert to a 3-bolt cam by using a 4X, 2006 Corvette gear.
Another common failure point on the 2007+ LS2 engines is the spring-loaded tensioner. We recommend converting to the wedge-shaped timing chain damper found on the early LS2 engines.
Upgrading the LS2 Car Engine Intake Manifold and Throttle Body
The stock LS2 intake manifold doesn’t flow well at all. After the cam, your next modification should be an aftermarket intake. There are several styles available depending on what kind of vehicle you’re running and the hood you are using.
If you’re trying to fit under the stock hood, the Fast 102 intakes are very good. They make more power and torque over a wide range. Gains of 20+ horsepower at the wheels are common. The short-runner MSD is an option if you are looking for more high-end power and don’t mind losing a bit down low. A little clearancing and spacing work may be required around the water pump area of your vehicle.
If the engine found its way into a car running well over 200 hp of nitrous, a backfire can blow the plastic intake apart pretty quickly. This is one of the rare instances a single plane cast manifold begins to make sense. It’s stronger and the air/fuel distribution is better. The main downside to single plane intakes is they typically loose a ton of torque down low and don’t start making more power until above 5,500 rpm.
Want to make big power and don’t mind cutting holes in things? Then a Tunnel Ram is for you. These commonly make around 35-45 more horsepower depending on the combination. Better yet, they don’t lose all the bottom end. A little lower at 3,500 rpm, matching at 4,500, and marching up past there.
How about the throttle body? At 90mm, it’s pretty good. Still, if you’re going big on the manifold you may want to go with one of the 102mm throttle bodies that match them.
Upgrading the LS2 Car Engine Fuel System and Tuning
Upgrading to larger fuel injectors is often needed to meet the demand of increased power.
The 34-pound LS2 injector was shorter than the earlier LS1 injectors but longer than the later LS3 injectors.
The factory fuel pump will become a limitation around 430 hp. So, plan on upgrading the fuel pump as well.
Tuning the computer changes the fuel and ignition curves to increase performance. Plug-in programmers are easy to use, but have limits.
If you plan on running a power adder or have a long list of upgrades planned, it’s recommended you take your car to a chassis dyno tuner who can give you a custom tune.
Upgrading LS2 Car Engine Cylinder Heads
The LS2 cathedral-port cylinder heads can be CNC ported for more airflow, and can be milled up to .030-inch for more compression.
Compression is already in the high 10.9:1, but can be bumped into the low-11s with the right cam and higher-octane fuel.
For high-rpm engines (7,000+), consider using the hollow-stem intake valves from an LS3. They are light and can be cut to 2.000-inch to fit the standard valve seats.
There are many aftermarket heads available for the LS2. Aftermarket heads flow better and have thicker decks to maintain a good 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. With a medium-sized cam and matching intake, 480+ hp at the wheels is easy to achieve.
Yet another option is bolting on LS3 heads, rockers, intake, and fuel rails. The valves are shrouded on a 4.000 inch bore which knocks down airflow and performance more than one would expect. For this reason, many elect to go with aftermarket cathedral port heads and aftermarket intake.
Adding an LS2 Car Engine Supercharger or Nitrous Oxide System
Many supercharger kits are bolt-on and work with stock internals and pump gas. More serious kits are available, but will require internal upgrades.
Nitrous kits are also available, inexpensive, and easy to install. Street kits have lower settings that work with stock internals. More power requires higher settings and upgrading the engine internals.
Street kits with up to 200 horsepower can be used with stock internals. More power requires higher settings, more octane, and upgrading the engine internals.
Either way you go, a 4-corner steam kit is another smart upgrade. It reduces hot spots in cylinder #7 that can cause the piston rings to butt and crack the piston’s ring lands.
Upgrading the LS2 Car Engine Rotating Assembly
A set of forged pistons should be high on your priority list.
The addition of valve reliefs also makes running bigger cams possible. When stroking, choose a piston with minimal skirt taper. This prevents the piston from rocking at BDC and scraping up the skirts.
Gen 4 connecting rods are stronger than the Gen 3 rods and have full floating pins. They can handle about 800 hp and 6,500 rpm in boosted applications. If you’re getting forged pistons, you should 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).
If you’re doing machine work though, you can upgrade to a 4.000-inch forged stroker crank. This will bring displacement up to 402 c.i.d. or more.
The following chart lists standard specs compared to common performance rotating assemblies.
|Standard vs. Performance Specs for LS2 Car Engine Rotating Assemblies|
|Gen IV LS Standard Spec||Stroke||Rod Length / Wristpin||Bore Size / Compression Distance|
|LS2 (6.0L car engine)||3.622 in.||6.098 in. / 0.9431 in.||4.000 in. / 1.338 in.|
|Common Stroker Combinations||Stroke||Rod Length / Wristpin||Bore Size / Compression Distance|
|6.0L to 6.7L||4.000 in.||6.098 in. / 0.927 in.||4.030 in. / 1.115 in.|
|6.0L to 6.7L||4.000 in.||6.125 in. / 0.927 in.||4.030 in. / 1.110 in.|
Upgrading the LS2 Car Engine Block
The LS2 engine block has a 4.000-inch bore diameter. The cylinders can be bored to 4.030 inches. However, we recommend leaving them as thick as possible when running boost.
The block can handle 850 horsepower. If you want to surpass this, a sleeved block with doweled main caps is a good idea. The bore can be opened to 4.125+ inches afterward for 427 cubic inches, or more.
(Information for this article originally appeared in this Upgrading the Gen. 4, 6.0L, LS Car Engines article at Summit Racing’s searchable database of FAQ tech info. Go there and search “LS engines” for a comprehensive collection of LS engine tech information.)
NOTE: You can find engine specs and detailed engine upgrade advice for every LS and LS-based Vortec truck engine in one place: The Definitive Guide to LS Engine Specs and LS Engine Upgrades.