[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. The truck version of the LS2 powered the TrailBlazer SS, SSR, and Saab 9-7X Aero. This article will focus on the truck 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 Truck Engine Upgrades
Basic bolt-ons: On a stock LS2 truck engine, the following can improve performance and fuel economy:
- A cold air intake. This removes the restrictive resonator between the intake and airbox.
- A colder thermostat. This allows for more aggressive ignition timing.
- An aftermarket exhaust system. Doing a rear muffler delete is another favorite.
- A computer programmer
- Electric fan kit. Free up power lost to the mechanical fan and clutch.
In addition to the basic modifications, there are a few preventative measures to tackle before running hard. Adding additional engine grounds is one. Another is a trans-cooler. The last and most important is to get the oil pump pickup extension. This moves the pickup to the back and keeps it from being uncovered under hard acceleration. A good time to tackle it is when you swap the cam, so let’s get into that.
[Every engine spec you’ll need for an LS2 truck project or engine swap can be found here: LS2 Truck Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More.]
Upgrading the LS2 Truck Engine Camshaft and Valvetrain
LS engines respond well to cam swaps.
The two factory LS2 truck cams are around 204/213 duration with just over .520 lift and both are decently matched to the long-runner intake. Some are tempted to use the LS7 and LS9 cams. Both are around 211/230 duration, which sounds like a good choice, but actually aren’t. They will pick up power at the very top of the rpm range, but lose power throughout most of the range a truck typically operates in.
A better choice is a dedicated aftermarket truck cam with narrower lobe separation and more advance. This will boost torque and give it a more-aggressive idle. Aftermarket LS2 truck cams are a little bigger than most because the original was performance oriented to begin with. Generally, intake durations starts in the 208 to 216 degrees of duration range. Getting into the low 220 range is possible, but a higher stall converter is recommended. Cams with .560 lift will live a long life with a fresh set of LS6 springs. Quick note: If you have a 2007 or newer LS2, you can convert to a 3-bolt cam by using a 4X, 2006 Corvette gear.
The trunnion bearings in the stock rocker arms are a weak point. A trunnion upgrade kit should be installed when you upgrade the valvetrain. The stock rockers are good for .600+ lift with this modification.
Another common failure point on the 2007+ LS2 engines is the spring-loaded tensioner. We recommend converting back to the wedge-shaped timing chain damper found on the early LS2 engines.
Upgrading the LS2 Truck Engine Intake Manifold and Throttle Body
The Chevy Trailblazer SS truck intake was the best factory cathedral-port intake. The 87mm throttle body is adequate for most power levels. Porting the factory intake is a popular option and a good value. If you’re looking for the last bit of power, the long runner FAST LSXR-T is recommended and accommodates larger 102mm throttle bodies.
Something to watch out for on these engines is the direction of throttle blade rotation. 2006-07 GM car throttle bodies with a silver blade rotated one direction. The truck throttle-body blades rotated the other direction and featured a gold blade in 2009. Be sure to get the right one for your specific LS2 engine.
Upgrading the LS2 Truck Engine Fuel System and Tuning
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 that you take your truck to a chassis dyno tuner who can give you a custom tune. Knowing you’re running high octane and have a 160-degree thermostat opens up the tuning window.
Depending on how much power you intend to make, upgrading to larger fuel injectors may be needed. Ask your tuner what injectors they prefer and have them ready to save yourself an extra trip to the dyno. 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 whp. So, you should plan on upgrading the fuel pump as well.
Upgrading LS2 Truck Engine Cylinder Heads
Looking for 450+ hp at the wheels naturally aspirated? You can achieve it with good drivability and power across the entire rpm range by upgrading the cylinder heads on your LS2 truck engine. Aftermarket heads reduce downtime and are cost-effective when you sell your old heads in good condition. A 220cc runner head is a good match with the TBSS intake.
Don’t mind a little downtime? The LS2 cathedral-port cylinder heads can be CNC ported to flow close to the aftermarket heads. With a bigger cam you can mill the heads for compression, but 11.25:1 is about the limit. If you are going through the heads, it’s recommended to switch to the light hollow-stem intake valves from an LS3. They can be cut to 2.000-inch to fit the standard valve seats and extend the rpm range up to 7,000 rpm.
Adding an LS2 Truck Engine Supercharger or Nitrous Oxide System
Nitrous kits are also available, inexpensive, and easy to install. Up to 200 horsepower is common on stock internals, but a proper tune and fuel quality are part of the equation.
Either way, 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.
Still looking for more? Let’s talk about bottom-end upgrades.
Upgrading the LS2 Truck Engine Rotating Assembly
It’s not easy to break an LS2 crank, but adding more cubes is always a plus. A 4.000-inch forged stroker crank brings displacement to 408 cid. The added torque will make a big difference in moving the truck.
A set of forged pistons with valve reliefs opens up the door for bigger cams, boost, and nitrous.
The Gen 4 connecting rods are strong, but forged steel rods are stronger and have better bolts.
The following chart lists standard specs compared to common performance rotating assemblies.
|Standard vs. Performance Specs for LS2 Truck Engine Rotating Assemblies|
|Gen IV LS Standard Spec||Stroke||Rod Length / Wristpin||Bore Size / Compression Distance|
|LS2 (6.0L truck 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 Truck Engine Block
The LS2 engine block has a 4.000-inch bore diameter. The cylinders can be bored to 4.030 inches, but it’s recommended that you leave them as thick as possible with .010- or .020-inch oversize pistons.
The block can handle 850 horsepower.
If you want to surpass this, a sleeved block with doweled main cap studs is a good idea. The bore can be opened to 4.125+ inches for 427 cubic inches or more.
(Information for this article originally appeared in this Upgrading the Gen. 4, 6.0L, Aluminum Block, LS Truck Engine 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.