FEV's Advanced Turbulence Assisted Combustion (ATAC) system involves modifications to the cylinder head, combustion chambers, pistons and intake system of the base diesel engine, a Volkswagen 2.0-liter TDI. FEV's lean burn combustion setup offers improved fuel efficiency and CO2 emissions when compared to conventional CNG technology.
The key to the efficiency of FEV's engine technology is its optimized compression ratio, which is adjusted so that it falls between the normal compression ratios of diesel and gasoline engines. FEV's lean-burning CNG-fueled concept engine will be on display from April 12–15 at the Cobo Center in Detroit, MI.
[Source: FEV Group]
Auburn Hills, Mich., March 14, 2011 – FEV Inc., a leading developer of advanced powertrain and vehicle technologies, announced today that it will exhibit a lean burn engine concept at the SAE 2011 World Congress that has been modified to run on Compressed Natural Gas (CNG). The engine is designed for use in light-duty vehicles, and demonstrates the potential of modifying passenger vehicle engines to achieve diesel-like fuel efficiency and power using CNG as an alternative fuel. The engine will be displayed in FEV's booth at the 2011 SAE World Congress, held April 12 – 15, 2011 at Cobo Center in Detroit. Gary Rogers, FEV, Inc. president and CEO made the announcement.
The Advanced Turbulence Assisted Combustion (ATAC) system was implemented via modifications to the cylinder head, combustion chamber, pistons and intake system to create high turbulence through an increase in the intake swirl from the baseline diesel engine. The lean burn combustion process also offers significant improvements in fuel consumption and CO2 emissions in comparison with more conventional CNG technology as a result of dethrottling and better combustion efficiency.
"The effects of our dependency on a petroleum-based infrastructure have recently been demonstrated on the global stage as we see fuel prices rise and automotive market capitalization decline." said Rogers. "It is a wake up call that we must develop the technology that can run on alternative fuel sources that are available both cost effectively and domestically. This engine demonstrates a potential near-term solution."
Natural gas offers significant benefits in comparison with conventional fossil fuels, due to inherently better lean burn combustion properties and reduced knocking tendency, as well as better mixture preparation characteristics. A diesel engine has been selected as the baseline for the development to enable the benefits of combustion at high peak pressures.
In developing the demonstrator, FEV implemented a number of alterations to a Volkswagen 2L TDI base engine design, including creating a custom intake manifold, requiring the modification of the direct injection system, creating a multi-point injection system similar to port injection. FEV also optimized the velocity of the charge entering the combustion chamber, the piston geometry, the type of spark plug (whether for stoichiometric or lean burn), and made necessary adjustments to the turbocharger. The compression ratio is adjusted so that it falls between a diesel and a gasoline engine compression ratio, resulting in higher combustion efficiencies.
In addition to the design of new components, FEV considered the increased strain on various components, such as valves and valve seats. Due to the operating conditions characteristic for CNG combustion, parts were designed to be more robust to mitigate excessive wear.
The FEV Group is an internationally recognized powertrain and vehicle engineering company that supplies the global transportation industry. FEV offers a complete range of engineering services, providing support across the globe to customers in the design, analysis, prototyping, powertrain and transmission development, as well as vehicle integration, calibration and homologation for advanced internal combustion gasoline-, diesel-, and alternative-fueled powertrains. FEV also designs, develops and prototypes advanced vehicle / powertrain electronic control systems and hybrid-electric engine concepts that address future emission and fuel economy standards. The FEV Test Systems division is a global supplier of advanced test cell, instrumentation and test equipment. The FEV Group employs a staff of over 1,800 highly skilled specialists at advanced technical centers on three continents. FEV, Inc. employs approximately 300 personnel at FEV's North American Technical Center in Auburn Hills, MI.