Chevy Corvette LS1 and LS6 - Power Plant

We Go Behind The Scenes At The St. Catharines Engine Assembly Plant, Where Corvette's Aluminum Heart Is Built

Barry Kluczyk May 1, 2002 0 Comment(s)
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Corvettes, as you probably know, are built in Bowling Green, Kentucky. But the LS1 and LS6 engines that fill the space between the front wheels come from farther up north

The Great White North, actually.

St. Catharines, Ontario, Canada is home to GM's LS1/LS6 assembly operations. Located in the Niagara Falls region, it's one of several GM Powertrain facilities in the area, including the legendary big-block house at Tonawanda, New York, and the carburetor and fuel injection works at Rochester. (To be specific, Rochester is no longer a General Motors plant; it belongs to Delphi, which was the parts-making subsidiary of GM that split off several years ago and is now an independent corporation.)

The plant has been building engines-and nothing but-since 1954. And though St. Catharines no longer incorporates a foundry, it still performs a great deal of finish machining to raw blocks, cylinder heads, and crankshafts prior to assembly. Currently, St. Catharines is the sole source for the Corvette's LS1 and LS6 (found in the Z06 model) engines, as well as LS1s for the F-car (Camaro and Firebird), and GM full-size trucks.

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More than 2,000 workers are employed at St. Catharines, spread out on 2.4-million-square-feet of shop floor. Of course, computers play a large part in the speed and accuracy of the assembly process, too. CNC mills do most of the machine work, while workers perform the delicate component assembly chores. This balance of man and machine produces about 2,000 versions of the LS1 small-block each day (and about 600 previous-generation small-blocks for some GM trucks).

It's a state-of-the-art process that's been refined over the years, particularly since the LS1 engine came online in the late '90s. But, rather than simply bolt together engines from drop-shipped components, St. Catharines still performs a great deal of machine work to the parts.

The engine blocks, for example, are delivered as raw castings. Each block is sent through a gauntlet of CNC mills to be drilled, tapped, and prepared for assembly. The same goes for the cylinder heads. Even the camshaft is ground and heat-treated at the plant.

Interestingly, the LS1 and LS6 engine blocks, though based on the same basic LS1 architecture, enter St. Catharines from vastly different paths. LS1 and LS6 blocks are cast in different foundries and with different methods. The LS1 block is cast in a semi-permanent mold, while the LS6's foundry makes use of a more traditional sand-cast process. Side by side, it's easy to tell the blocks apart: there are crankcase ventilation differences, and the LS6 block is simply darker than the LS1.

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The assembly process begins with raw block castings for the LS1 and LS6, which are delivered to St. Catharines from separate foundries. This is a shipment of un-machined LS6 blocks, which are made with a traditional sand-cast method. LS1 blocks are formed with a semi-permanent mold. Although otherwise un-machined, the aluminum blocks are delivered with their iron cylinder liners in place.

To ensure consistency and accuracy among the engines on the assembly line, workers' torque wrenches are programmed to "torque to spec," and, after a while, we lost count of how many quality checkpoints were located along the line. The tolerances for the LS1 and LS6 engines are quite tight, and it doesn't take much for a part to be rejected. In fact, some specs aren't measured in thousandths or tens of thousandths, but microns.

The CNC machines help ensure adherence to specifications. And, in this day of "just in time" component delivery from outside suppliers, we found it fascinating to learn that St. Catharines grinds crankshafts and camshafts from billet stock. Certainly, there are pre-made parts, such as the throttle-body/intake plenum assembly, but almost all reciprocating components are either made or machined in the plant.

Witnessing the assembly process revealed some interesting methods, all done for the sake of efficiency. The camshaft is inserted by machine, while pistons are handled by separate installers. That means one worker is assigned to piston #2, for example, while another is assigned to piston #7. And, an engine's cylinder heads are installed simultaneously by a robot, then tightened in a separate station by a machine that torques all head bolts at once.

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There's an entire department at St. Catharines dedicated to camshafts. These completed cams are the result of numerous computer-controlled shaping and hardening processes. St. Catharines starts with completely round steel billets and starts grinding them into camshafts.

Interestingly, at the end of the production line, the LS1 engines aren't fired. They're filled with oil and spun to 2,000 rpm for "cold" testing, to ensure the oiling and coil-on-plug ignition systems work. They're then sent for some final balance checks, loaded into a shipping carrier, and sent to Kentucky. The first time they'll run is after they've been installed in a car. (For those who've toured Bowling Green, it's the "giving birth" part of the assembly.)

As for LS6 engines, which boast a higher redline and some different reciprocating components than the LS1, they're sent to a separate station for a more specialized balance check. There, each LS6 is fired on natural gas and run for about two minutes on a transducer. If an imbalance is detected, weight is modified at either the harmonic balancer or flywheel. It's an additional step that ensures the LS6 is one of the smoothest engines in the world.

"Everybody in the plant follows the business closely," said one of our guides. "They're all aware that we're the only ones building Corvette engines, and they're very proud of it."

If the cleanliness and attention to detail demonstrated throughout our tour are an indication, St. Catharines' workers have every right to be proud. It's work more than worthy of America's Sports Car.

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