We’ve all heard stories of racers using an LS engine that was pulled from their local boneyard, that has over 150,000 miles of use under its belt. They slap on a power adder that brings it near – or over – the 1,000-horsepower range, and the engines live through the abuse – at least for a while.
Most enthusiasts feel more comfortable knowing the mill in their hot rod has been rebuilt. If you’re looking for big horsepower numbers, it will take some common-sense performance upgrades and general engine blueprinting. It can be accomplished without a long shopping list of exotic (expensive) purchases.
Know What You’re Working With
We tapped into the knowledge of Chad Golen from Golen High Performance Engines to provide some insight. His shop has become a popular choice for the performance enthusiast to procure everything from hardcore LS-performance machine-shop services to complete LS1 crate and racing engines, and Chevrolet LSX custom components.
“When you look at the used LS-engine market, typically, someone is bringing their LS engine here for machine work or for us to rebuild for performance or racing,” Golen explains. “The newest-generation 6.0-liter truck engine is the hot ticket these days. Since they have been in production as 4.00-inch bore (364 cubic-inch) blocks since 2005, they have made their way into salvage yards.”
Even with 6.0-liter engine’s popularity, the smaller OE versions of the LS platform have similar strong points. They are also a favorite engine of choice for hot rodders and street/strip applications. The 4.8- and 5.3-liter engines compute to 293 and 325 cubic-inches respectively. Whatever your use or liter selection of size, many of the performance upgrades are the same across the board.
“The 6.0-liter engine provides a strong foundation,” Golen expands. “They come with heads that have 210cc intake-runners, and most have the 317 casting-design heads. This head flows great from the factory. You can deck the heads to get a little compression increase out of the stock design pistons, add a decent cam and intake manifold, and you can break 500-horsepower without even trying.”
There is a large variety of the latest LS engines – even in just the 6.0-liter variety. Many versions were produced for unique Corvette, Cadillac CTS, and Camaro ZL1 applications. “These engines feature a strong, 3.622-inch stroke crankshaft,” Golen describes. “Many enthusiasts are using those original GM cranks with turbos, pushing upwards of 850-horsepower with no issues.”
Even though we are touting the longevity of factory-stock components for performance use, Golen recommends some attention be paid to certain areas. He is a big proponent of balancing the original GM crankshafts for a solid platform. He will typically regrind the cranks, though sometimes they need only a polish of the journals.
What Machine Work Is Really Needed
The latest generation in all LS engine designs utilizes tight bearing clearances as compared to the “good ‘ol days.” A crankshaft turned and/or polished for .002- to .003-inch tolerance related to bearing clearance will net your desired oil pressure with a light viscosity oil.
“A lot of people like to use standard oil pumps, which yield slightly lower pressures,” Golen discloses. “I set up our performance LS engines with .0025 bearing clearance and strong Clevite cam bearings to handle increased valvetrain pressures. We use Melling high-volume pumps that achieve proper 35 to 40 psi of oil pressure with a 5W30-weight performance oil.”
Related to the crankshaft, the main caps and lower block design have made massive jumps in strength over earlier generation GM blocks. Golen highly endorses the use of ARP bolt and stud kits to create an exponentially stronger bottom end.
Golen typically utilizes a SCAT Crankshafts-brand I-beam, forged-steel rod that is 6.100 inches long, with full floating pins. “They’re an inexpensive rod that has been used in many of our 550-horsepower engines with no questions asked,” said Golen. “My favorite piston is a Mahle Motorsports forged-piston and ring pack. This pack has coated piston skirts, a plasma-moly ring set, and tends to be a good piece. With this basic piston/rod combo, you have replaced two of the weakest points in the LS engine.”
I have a connecting rod from a junkyard 6.0-liter core engine that I show people who want to use the factory rods and pistons in a performance application. Though every bearing was beautiful and the engine internals were clean as a whistle, it was broke dead-center. – Chad Golen
Headed In The Right Direction
Golen has suggestions about what to look for when scoring a boneyard engine for rebuilding. Short of dismantling the engine, he explained there are not a lot of telltale indicators. Even a peek under the valve covers for signs of frequent oil changes may not reveal much. His first recommendation is to ask a reputable machine shop to check if the heads are “warped to the moon.” Chad has experienced many cases where an engine can appear clean, but the heads have warpage beyond use for performance rebuilding.
The LS heads use a “roller-trunnion” rocker arm with strength far superior to their stamped-steel ancestors. The needle bearing trunnion is housed within the cast-steel body with a cylindrical pivot on both sides of the rocker arm stud.
Though these OE needle-bearing rocker arms are strong enough for use with conservative cam profiles on a performance level, Golen recommends the addition of a roller bearing retrofit kit, widely available for these rockers. “There are many aftermarket trunnion kits, which are fairly inexpensive and can be installed in the home shop.”
The new trunnion kits install within the factory rocker arm, but use a “caged” needle-bearing housing. In addition to material strength of the cross shaft, the cage adds strength and contains the needle bearings in case of any failure.
Pushrods are essential components that require upgrade consideration when using any form of performance cam or valve springs. “It’s not a huge deal,” says Golen. “Many good brands, such as COMP Cams and Smith Brothers Pushrods offer a 5/16-inch pushrod that has .080-inch walls, is black oxide-hardened, and are more than acceptable.”
Intake manifolds can be a user’s choice for the LS engine. A factory truck intake is capable of producing 500 horsepower, and produces a ton of torque. The only problem for many, is the overall appearance.
“Once your cam, throttle body, and injector sizes dip into the 550-horsepower level, you will need to go for either a Holley Performance high-ram, MSD Performance Airforce intake, or even one of the new Holley sheetmetal intakes,” Golen describes. “Any good increase in performance level is based around a match of the camshaft, compression ratio, 36- to 40-pound fuel injectors, and the intake-manifold design. Though it’s a sound theory with all engines, one miss in matching with this components group can cost you horsepower.”
The jump to an 850- to 1,000-horsepower engine typically requires a supercharger, turbo, or doses of nitrous oxide. “At that point, I would go with an aftermarket block and heads,” says Golen. “I will draw the line with the factory block at that point. The biggest reason is the head-bolt clamping. You only have four bolts per cylinder on factory GM blocks and heads compared to the six-bolt Motorsports design.”
Wrapping up the knowledge Golen passed along from his mass of LS performance builds, the final item we discussed was gaskets. He cited that GM Performance or Fel-Pro gaskets work fine overall. “There is no need to step up to more exotic head gaskets until you get into applications with big boost,” Golen ends.