The advancement of GM's LS engine platform is comparable to--and perhaps just as important as--the development of the original small-block Chevy. Introduced in the '97 Corvette, this "new" engine family replaced the traditional small-block and big-block Chevy engines from GM's powertrain lineup. It's currently found in numerous cars, SUVs, and trucks and is considered to be the GM V-8 engine of the foreseeable future.
Designed with the same 4.400-inch bore centers as the Gen I and Gen II small-blocks, the LS-series design, which includes a deep-skirt block and six-bolt main caps, has proved itself capable of supporting tremendous power. Not surprisingly, performance enthusiasts and racers alike have embraced the LS--particularly C5 and C6 owners who are packing various configurations of the engine under their hoods.
But just because the LS wasn't factory installed in one's Corvette doesn't mean it can't be used to power up an older car. The compact dimensions, lightweight aluminum block and heads, and burgeoning retro-fit market make the LS a smart, contemporary choice. And with a variety of carburetor swap kits, it's easy to drop an LS engine in a pre-EFI car.
The idea of building a powerful LS engine for an older car intrigued us, so we started bending the ear of World Products' Bill Mitchell. World recently introduced its own version of the LS engine in the form of the Warhawk cylinder block and heads. Although GM offers a number of production-based crate engines, Mitchell saw an opportunity to carve out a niche of the LS world for his company.
"The LS engine is the performance engine of the future," he says. "We think there's room for a high-performance-oriented family of components that is suitable for the street or strip."
Like World's Motown small-blocks and Merlin big-blocks, the Warhawk is based on GM's design, but with enhancements designed to improve strength and support greater power. It also has provisions for six bolts per cylinder head, which shores up one of the LS engine's few shortcomings: head sealing under very high load or boost pressure. GM Performance Parts' LSX block comes with six-bolt provisions, but it's currently available only in iron. The Warhawk block is a lighter-weight aluminum piece with iron cylinder liners.
Here's a quick look at the Warhawk's key features:
* Made of A357-T6 aircraft aluminum alloy
* Billet-steel main caps with APR 200,000-psi main studs
* Reinforced block design with six-bolt cylinder-head capacity
* Priority main oiling circuit
* The water jacket surrounds the cylinders and separates them from the head-stud holes. This increases the strength of the cylinder area and allows the studs to reach deeply into the block
* Two deck heights are offered: 9.240-inch (GM production height) and tall-deck 9.800-inch
* Can accommodate 4.000-inch and 4.125-inch bores (depending on the sleeves and requisite support)
* Motor-mount provisions from both early- and later-style engines
* Weighs only 133 pounds with the sleeves and main caps installed
When figuring out displacements, the Warhawk's 9.240-inch-deck block allows for a 4.000-inch stroke, which yields a maximum displacement of 404 ci (with 4.125-inch bores). The 9.80-inch deck enables a whopping 4.500-inch stroke, which, when combined with 4.125-inch bores, delivers a big-block-like 454 cubes. Because the tall-deck block pushes the heads farther apart, spacers are needed to run production-type intake manifolds. To anyone who's familiar with World Products' capabilities, it should come as no surprise to learn the company offers the spacers, as well as heads themselves. In fact, World manufactures two LS-style heads: the cathedral-port LS1X heads and the rectangular-port LS7X.
Although World was not yet offering Warhawk crate engines at the time of our buildup, the company was offering a variety of short-block assemblies and partial engines, the most popular being a 481-inch combination that uses the tall-deck block. For our project, we started with World's 427-inch short-block with LS1X heads, PN 103251A. It uses a standard-deck block (9.240 inches) and 4.125-inch bores. With a 4.000-inch stroke, it gives our engine the classic big-block displacement of 427 ci. It also is filled with forged reciprocating parts.
And because World's short-block doesn't include a camshaft, we looked to GM for an off-the-shelf LS7 bumpstick, PN 12571251. It has a lot of lift, and we figured that any cam good enough for the Z06 ought to do just fine for our street-based project.
A slew of carbureted intake systems have been developed for the LS engine, and they work great with the Warhawk. We used a high-rise, single-plane manifold and an 870-cfm Dominator-type four-barrel carb. It sounds like a lot for the street, but World Products insists the combination is docile enough for traffic duty.
Because the Warhawk block is based on the LS engine, it is designed to accommodate production-style accessories and components, including the oil and water pumps, the front cover, the various sensors to trigger the ignition and adjust timing, the ignition coils, the front-end dress kit, and the oil pan. We used a mixture of GM and aftermarket parts, including a complete MSD ignition system and controller kit.
The Warhawk accommodates the Z06-type dry-sump oiling system, so builders can use either the low-profile factory LS7 pan and a remote oil reservoir or a conventional wet-sump pan. The inlet/outlet ports for the dry-sump pan will interfere with some crossmembers, so unless you really want the exoticness of the dry system, stick with a conventional pan like the GM F-car unit. The Corvette LS pan has wings for high-load cornering, but on a street/strip car, the wings only interfere with the chassis.
Building a Warhawk-based engine is just like building a GM LS engine. In fact, our World Products project engine used a number of GM accessories to round out the assembly. Some of the fasteners are torque-to-yield types, meaning the final torque specs are reached with a torque-angle meter or similar tool.
And while the LS-type engine is different than a conventional carbureted mill with a distributor, getting it up and running is surprisingly easy and straightforward.
Here are the basics of what you need:
* Ignition system - GM or aftermarket (such as MSD), including coil packs, plug wires, and spark plugs
* Crankshaft-position, camshaft-position, and other sensors
* Ignition controller
With the MSD ignition kit, wiring the engine and getting it running was a snap. The valve-cover-mounted ignition coils connect to the wiring harness with only a single connection per side. The harness also plugs into the crank- and cam-position sensors, as well as a few others, and that's about it. When everything is plugged in and the engine is started for the first time, the ignition control automatically sets the timing--no timing light required.
By the way, one of the best guides to setting up an LS engine in an older vehicle is available from GM Performance Parts. It's called LS1 Engine Kit Installation Guide, and it carries PN 88959384. While the title says "LS1," the content is applicable to any LS-based engine swap.