General Motors 2019 5.3-L OHV V-8, the first GM engine fitted with Dynamic Fuel Management, is SAE-rated at 355 hp at 5600 rpm and 383 lb·ft (510 N·m) at 4100 rpm. (GM)
GM adopts advanced cylinder deactivation for 2019 Chevy Silverado V8s
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Calling 2019 variants of its 5.3-L and 6.2-L OHV V8s for the 2019 Chevrolet Silverado fullsize pickup “the most advanced gasoline V8s in the [Chevrolet] brand’s history,” GM introduces Dynamic Fuel Management, a high-tech new variation of the company’s longstanding Active Fuel Management cylinder-deactivation system.
“Chevrolet first introduced its Active Fuel Management cylinder deactivation system in 2005, and Dynamic Fuel Management is a natural progression of the technology,” said Jordan Lee, chief engineer for GM’s small-block engines. “Dynamic Fuel Management enables only the cylinders needed to deliver the power you want, seamlessly delivering the best balance of power and fuel economy.”
At a press program to introduce the new DFM-equipped V8s, Lee said equipping the 5.3-L and 6.2-L V8s with the DFM system was “equivalent to making an all-new engine.” The V8s will serve along with an all-new 2.7-L turbocharged four-cylinder and Chevrolet’s 4.3-L V6—not to mention an all-new 3.0-L inline six-cylinder diesel coming later—to cover the 8-model 2019 Silverado lineup.
The new DFM system that has seen extensive initial development at Tula Technology and mega-supplier Delphi, works from a “map” of 17 distinct cylinder-firing regimes that control the firing individual cylinders; the previous AFM design allowed only for switching between 8-cyl. or 4-cyl. operation. Brief drives in DFM-equipped trucks show constant fluctuation between the 64 available “fractions” of 8-cylinder operation based on the 80-times-per-second ministrations of a microcontroller to determine how many of the cylinders are required in relation to the driver’s request for torque. The system then decides which cylinders to fire—and in the optimized order.
The DFM system controls valve actuation via solenoids that meter oil pressure to control ports in each cylinder’s valve lifters. To shut down a cylinder, oil pressure is diverted from the two-piece lifters, causing them to collapse on themselves, preventing the cam lobes from opening the valves. When the cylinder is reactivated, oil pressure is restored to the lifter control ports and the latching mechanism restores normal cylinder function.
To help cancel the minor irregular vibrations transmitted by cylinder switching, the automatic transmissions paired with the new V8s—an 8-speed for the 5.3-L and a 10-speed for the 6.2-L—are fitted with a specially-designed damper that varies its effect based on the amount of torque-converter slippage dictated by the powertrain controller.
The enhanced sophistication of the DFM system allows some form of cylinder deactivation roughly 9% more than with the former AFM cylinder-deactivation system, said Lee—and working out the calculations for DFM’s algorithms swallowed 12.4 million hours of computer processing time.
The company has yet to release fuel-economy figures for the new all-aluminum V-8s. The 5.3-L is SAE-rated at 355 hp at 5600 rpm and 383 lb·ft (510 N·m) at 4100 rpm.
The 2019 DFM-equipped 6.2-L V8 develops an SAE-rated 420 hp at 5600 rpm and 460 lb·ft (621 N·m) at 4100 rpm. Both are built at GM’s engine assembly plant in Tonawanda, NY.
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