General Motors is consolidating four existing powertrain engineering facilities in Wixom, Ypsilanti, Romulus and Warren, MI - relocating about 1,200 employees from the existing facilities to Pontiac, MI in a brain trust expected to validate both conventional gasoline-based powerplants, but also diesel and flex-fuel engines, hybrid transmissions and electric drives.

CEO Rick Wagoner, Powertrain Executive Vice President Tom Stephens and a handful of politicians pressed a ceremonial start button on July 25 to dedicate a new Powertrain Engineering Development Center (PEDC). The 450,000 sq. ft. facility sits adjacent to the headquarters of GM's Powertrain division.

The new center will be responsible for global powertrain development for GM working in conjunction with smaller centers located in 11 countries around the world. General Motors claims the Pontiac facility is the largest and most technologically advanced facility of its type in the world. The systems being implemented in Pontiac are common with those used at all of GM's other facilities allowing them to share data and run tests concurrently around the clock.

During a briefing and tour of the facility prior to the dedication,  Vice President of Powertrain Engineering Dan Hancock explains that one of the company's goals is to advance its Road to Lab to Math (RLM) strategy. The intent is to shift more powertrain development work from vehicle testing upstream to lab and mathematical simulation testing. By testing more concepts in simulation and in the lab, fewer expensive prototype hardware iterations will be required. Hancock announced that by the end of 2008, GM will have saved a cummulative $200 million thanks to the new development and testing processes.

Hancock declares that the new processes and procedures have allowed GM to eliminate 10 weeks from the powertrain development process along with one of three prototype hardware phases. This is accomplished by dramatically increasing the simulation and hardware testing capabilities.

The PEDC is responsible for design and validation of all types of powertrains including gasoline, diesel and flex-fuel engines, conventional transmissions, hybrid transmissions and E-Flex electric drive systems. The test area consists of two wings containing 120 new test cells. There are both fueled (for internal combustion engines) and unfueled (for transmissions and motors) cells with the latter being used to evaluate transmissions and electric drive motors. Twenty of the new cells are dedicated to testing electric motors used in hybrid and electric drive vehicles.

All of the new test cells use a newly developed palletized installation system. Traditionally, dynamometer cells use a fixed bed plate to which the test units are mounted and connected to the dynomometer and all the ancillary systems. This process can take up to 24 hours. General Motors developed the system in conjunction with powertrain testing specialist AVL. The new system allows technicians to completely assemble the test configuration including all the control systems on a pallet outside of the test cell. The pallet which can weigh up to 2 tons when a fully dressed and installed engine is then moved into the cell using an air cushion cart that can be pushed by one person.

AVL and GM have developed a quick connect system that requires no tools to connect the dynamometer, fuel, exhaust, cooling and electrical power.  A complete installation takes less than twenty minutes for a single technician. By not tying up the cells during changeovers, the cells can be kept running more of the time allowing more testing to be completed outside of a vehicle. Other companies have done palletized dynamometer configuration but GM's system is believed to have the fastest changeovers with others still requiring several hours.

GM has incorporated several other innovations into the new center that are thought to be industry firsts. One is the tilt test stands. Flight training simulators have long used a similar concept where a cockpit is mounted on hydraulic rams allowing the trainees to feel the forces associated with their actions. Mercedes-Benz has a similar simulation unit where a complete vehicle can be mounted on a platform to evaluate driver behavior in various dynamic conditions.

Two tilting test stands (one each for engines and transmissions) are being installed in the PEDC. These will be used to test fluid flow management inside of the engines and transmissions. Traditionally, the flow of oil and other fluids during dynamic conditions could only be tested on the vehicle. Unfortunately, those kinds of conditions can be hard to replicate on a vehicle and can be dangerous if the hardware fails during a test. The tilt test stands are each equipped with two dynamometers and can generate up to 1.3g of acceleration on the test components with up to 53 degrees of tilt in tow axes.

Another problematic aspect of testing in vehicles is climatic evaluation. In the past, carmakers have had to take vehicles to far northern locales, such as Kapuskasing, Ontario for extremely cold testing or Death Valley, CA for hot weather. In these locations engineers will have to leave a vehicle stationary for up to 24 hours to soak all components to a given temperature before starting. Unfortunately, weather conditions are limited to certain times of the year and can't always be relied upon.

GM has developed climatic test enclosures that are used in conjunction with the palletized system to for testing at temperatures from -40 to 60 degrees C. After a test pallet is prepared, an insulated enclosure is placed over the pallet. The pallet is then placed in a temperature soak chamber. Once the appropriate temperature has been reached, the pallet can be quickly moved to a test cell with the enclosure to maintain temperature. In the test cell, GM can control not only the temperature but also the ambient pressure and humidity to evaluate performance at different altitudes and weather conditions. This allows for year-round climatic testing in controllable and reproducible conditions before a vehicle is ever built.

One of the most important development projects currently underway at the Pontiac PEDC is the E-Flex powertrain that will be used in the upcoming Chevrolet Volt. The electric drive cells are being used for development and durability testing of the drive motors. Fueled test cells are testing the flex-fuel 1.4L engine and generator combination that will be used as the range extender. All of the fueled test cells are capable of running gasoline, diesel and ethanol engines.

One of the cells has even been certified for testing heavy-duty vehicle emissions. Unlike light duty vehicles which must undergo emissions certification as a complete vehicle on a chassis dynamometer, heavy-duty applications can go into such a wide variety of vehicle configurations that the engines are tested on a dynamometer alone.

With so many powertrains being tested, the development center generates a significant amount of emissions as well as heat from the dynamometers. Energy from the test cells is being used to generate up to 15 percent of the facility's power requirements. The emissions are being treated by a quartet of regenerative thermal oxidizers (RTO) installed between the two wings of the test area. These RTOs eliminate 96 percent of the carbon monoxide and volatile organic compound emissions from the facility.  

By the end of 2008 when all employees have moved in, 4,300 people will work at the Powertrain Engineering Development Center and GM will have spent $463 million dollars on the project.

JULY 2008