Image: GM Powertrain Communications
by Hib Halverson
The Performance Build Center is a GM Powertrain facility in Wixom, Michigan, about 30 miles northwest of Detroit. The 100,000 sqft. "PBC" is dedicated to assembling high-performance engines for certain limited production cars. The PBC is unique in the GM system because its engines are assembled mostly by hand. It's also unique in that it allows customers to come in and help assemble its products. That program, the "Corvette Engine Build Experience," is an option with ZR1s, Z06es and Grand Sport Coupes with Z52.
The idea for the Performance Build Center goes back to late 2002 and was GM Powertrain Vice President, Ed Koerner's brainchild. Back then, Ed headed-up Powertrain Engineering and recognized a need for a low-volume manufacturing facility which could make engines for a small but "...passionate customer constituency who want high-performance and the utmost in quality." Koerner, also, felt a "hand-built" engine could be marketed as a "pride-of-ownership" attraction to customers buying some of Powertrains's most unique products, such as Corvettes, certain Cadillac V-series models and a few of the premium crate engines sold by Chevrolet Performance. In a more practical sense, Ed Koerner wanted GM Powertrain to have the capacity to build unique products which could not be manufactured in a cost- or quality-effective manner by one of GM's high-volume engine plants. Finally, he wanted the flexibility to build all kinds of high-performance engines–4-, 6- or 8-cylinders, OHC or OHV, supercharged or normally aspirated–in one plant. Ed Koerner retired in late 2009 as GM Vice President of Engineering, after 40 years at GM which included a stint as Chief Engineer for the Small-Block V8. The PBC turned out to be one of Ed's legacies.
Work began on the Performance Build center in early 2003 and it took nearly a year to renovate the building, install the production equipment and furnishings, develop the manufacturing process then train the engine builders.
During '03, those tasked with setting-up the PBC toured other low-volume high-performance and racing engine production facilities. Some were in their own backyard, like long-time Chevrolet engine builder Katech, Inc. in nearby Clinton Township, or Lingenfelter Performance Engineering in Decatur, Indiana. Other sites visited were NASCAR engine shops in the Southeast, such as Hendrick Motorsports and Earhardt-Childress Racing Engines in North Carolina. They also traveled overseas to visit some of the best-known niche carmakers in Europe.
The Performance Build Center process is a mix of the best of what was learned visiting specialty and racing engine builders and manufacturing techniques GM already used in high-volume engine production which proved useful in a low-volume environment. The starting point for the PBC's quality expectations were standards GM Powertrain already had in place and which had resulted in a number of Ward's "Best Engine" and J.D. Power Initial Quality awards. To ensure the highest-quality, specialized engines, the final version of the quality control procedure merged the best practices of low-volume niche manufacturers with GM's established QC standards.
One bedrock philosophy of the Performance Build Center is the "one man–one engine" idea. "It's a premium manufacturing technique for premium products," Tim Schag, the Performance Build Center's first Plant Manager, told media when the facility opened in early-'04. "This process brings a higher level of quality, because each builder is personally involved in every aspect of the assembly."
Each builder "owns" an engine for the entire assembly process. Currently, there are 16 builders and the rate of production is about 27 engines a day. Clearly, engine assemblers or are a key link in the quality chain at the Performance Build Center. The initial compliment of engine builders was selected from Powertrain's experimental engine lab in Pontiac, Michigan for their experience in hand-building specialty engines and their union seniority. Since then, assemblers have continued to come from Powertrain's experimental side or from the group which builds engines for the vehicle development groups.
The facility has three assembly areas, each arranged in a U-shape and divided into 15 stations. Each station contains the workspace and specialized tools needed for one specific assembly procedure. Engines are moved from station to station on a "cart"–an industrial-strength engine stand with locking wheels. Adjacent to these assembly areas is a large parts stock, "cold test" and "hot balance" cells along with a shipping/receiving area.
Electronic monitoring of fastener installation and computerized record keeping are key components of the quality effort at the PBC. The majority of fasteners are tightened with power-operated, torque- or torque-angle-sensing, data-recording "wrenches". The builder positions the wrench and controls its operation, but physically applies no torque. The power-driven wrench senses torque applied or the amount the fastener is turned. If the proper torque or torque angle has been achieved, a green indicator light comes on and the wrench sends tightness data to the Performance Build Center's computer system which has a record of most of the bolts and nuts on each of the engines PBC has built since it opened.
Each builder makes a computer entry via a bar code scan as an engine enters or leaves a station and as each assembly operation required at that station is completed. Only when all quality checks have been made is the engine stand rolled to the next station. As a builder finishes in one station and pushes his or her engine to the next, another builder moves into vacated station. The process can be stopped if a problem is discovered.
Once an engine finishes at the last station, it is removed from the cart with a hoist, the flywheel is installed and the engine is weighed. Then, it's moved to the cold test facility, an enclosed, electric-motor-driven test cell where the engine is motored at a variety of speeds. Sensitive strain gauge devices measure the torque necessary to turn the engine's crankshaft and other sensors measure air flow, engine speed and a host of other parameters. That data is recorded and processed by a computer. This cold test rig can measure torque fluctuations so small and with such fine resolution that PBC Engineering Manager, Rob Nichols, can tell if a set of rings in one cylinder is not sealing properly, if there is a "nick" on a valve seat insert or an intake manifold seal is leaking. The cold test also detects abnormal noises. It checks spark timing, compression ratio, oil pressure, exhaust pressure and intake vacuum. It, also, verifies that the crankshaft and camshaft position sensors are functioning correctly. That's only part of what cold test does. An entire article could be devoted to just the cold test procedure.
The engine finishes in the hot balance cell were it's run for a short period on natural gas while the engine's dynamic balance is verified. If necessary, the operator makes a tiny change in flywheel or harmonic damper mass to fine balance the engine. Once these procedures are completed, the engines are packed for shipping.
The first projects the Performance Build Center took on were the LS7 engine, which would debut in the 2006 Corvette Z06, and the LC3, a supercharged Northstar V8 produced from 2006 to 2009 for some V-series Cadillacs. The first engine, a late-development-stage LS7, was built on 24 February 2004. Since then, the PBC has built about 50,000 engines.
At this writing, in Q3-2012, the Performance Build Center currently manufactures eight products. It makes three production Corvette engines, the LS3 for Grand Sport Coupe manual transmission Z52 applications, the LS7 for the Z06 and the LS9 for the ZR1. All three of these have dry sump oiling systems not easily assembled by highly automated plants. PBC, also, assembles the aftermarket, crate engine versions of the LS7 and the LS9 marketed by Chevrolet Performance and it builds the three engines, a 7-liter and two supercharged 5.3-liter V8s, available from Chevy's "COPO Camaro" drag racing program.
C6 is done at the at the end of the 2013 model year. At this writing, "build-out" will be at end of the first quarter and, at that time, production versions of the Corvette Gen IV Small Blocks will be discontinued. While no official announcement has been made so far, it's possible the Performance Build Center will continue to build the aftermarket, LS7 and LS9 crate engines along with those for the Chevy Performance COPO Camaros.
At this point, GM Powertrain hasn't announced what, if any, C7 Corvette engines will be built at the PBC nor has Chevrolet said anything about the future of the "Corvette Engine Build Experience" option but, it's likely no decision will be made on those issues until whatever is to replace the current Z06 and ZR1 is announced.