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Gas Mileage With a Punch! 355-Horse 2019 L84 5.3 Chevy V-8 Can Burn E85

John Gilbert May 29, 2018
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The big draw to E85 for gearheads was its 105 octane rating that’s no longer posted on the pump. It’s been a while since there’s been any mention of E85 connected with the new vehicles, but E85 is still around, and now with E10 gasoline prices going up there’s almost a one dollar-a-gallon difference in price. Our theory is California’s recent tax increase on a gallon of gasoline doesn’t affect the price of ethanol.

That’s in Southern California and of course wherever you might be prices, and availability can vary. I bought my first flex-fuel vehicle a 2000 S-10 brand new and at the time there was only one E85 pump in all of California an average Joe could buy E85 from. There was an E85 pump at Lawrence Livermore National Labortory, Vandenberg AFB, and a couple of other not for public consumption places.

I never got a chance to burn E85 in the little S-10, but in 2005 I bought a Flex-Fuel GMC Sierra with a 5.3L L59. The advantage to driving a Flex-Fuel vehicle over a standard E10 ready car is not having to worry if E15 ever becomes the national standard. It’s interesting to note that at a roundtable with a major fuel filter manufacturer our editors were told gasoline filters were only tested to an E10 threshold. And we don’t think there is anyone manufacturer, or individual that can tell you whether your E10 rated gasoline filter will dissolve plug the fuel system when E15 reaches it.

Its reported and we’ve found it to be true due to less BTUs (British Thermal Units) the fuel mileage on E85 with its necessary 35 percent richer fuel mixture isn’t as good as gasoline. My personal experience in daily freeway traffic the GMC averages 13.3 mpg on E85 and climbs back to 15-16 mpg on 87 octane E10. Another interesting side effect of E85 is it takes longer for fresh engine oil to look dirty because there’s less crankcase contamination, and best of all every engine likes to perk up with extra octane and a much colder inlet temperature and its felt in seat of the pants acceleration.

With the focus on the 2019 5.3L L84 in comparison to the Flex-Fuel L59 of 2005 there’s been a world of advancements in the battle to extract better fuel mileage. In fact across the board from the 5.3L to the 6.2L flagship V-8 modern technology has kept Chevrolet and GMC engines in the lead as the World’s most sophisticated pushrod (OHV) engine.

E85 5 3l 2019 002 2/3
E85 5 3l 2019 003 3/3

The all-new 2019 Chevrolet Silverado 1500 will offer the most advanced gasoline V-8 engines in the brand’s history: updated versions of the proven 5.3L and 6.2L V-8s with Dynamic Fuel Management. This industry-first cylinder deactivation technology enables the engines to operate in 17 different cylinder patterns to optimize power delivery and efficiency.

“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, Small Block chief engineer. “Dynamic Fuel Management enables only the cylinders needed to deliver the power you want, seamlessly delivering the best balance of power and fuel economy.”

Compared to Active Fuel Management, which alternates between eight- and four-cylinder modes, DFM features 17 cylinder patterns. That greater authority mixes cylinder patterns constantly to optimize efficiency and power delivery at all speeds.

During an industry-standard test schedule, the 2019 Silverado 2WD with the 5.3L and DFM operated with fewer than eight active cylinders more than 60 percent of the time, 9 percent more than a comparably equipped 2018 model with AFM.

DFM is powered by a sophisticated controller that continuously monitors every movement of the accelerator pedal and runs a complex sequence of calculations to determine how many cylinders are required to meet the driver’s requested torque. It can make this determination 80 times per second.

An electromechanical system deactivates and reactivates all 16 of the engine’s hydraulic valve lifters, controlling valve actuation. The system uses solenoids to deliver oil pressure to control ports in the lifters, which activate and deactivate the lifters’ latching mechanisms. When a cylinder is deactivated, the two-piece lifters effectively collapse on themselves to prevent them from opening the valves. When the cylinder is reactivated, solenoids send an oil pressure signal to the control ports on the lifters and the latching mechanism restores normal function, allowing the valves to open and close.

“The increased variability of Dynamic Fuel Management means the engine will operate more often with a reduced number of cylinders, which saves fuel across the board,” said Lee. “Better yet, the transitions are transparent, and because the system is torque-based, you’ve always got that satisfying feeling of power on demand that comes from Chevy’s Gen V Small Block V-8 engines.”

The 5.3L V-8 with DFM is SAE-certified at 355 horsepower (265 kW) and 383 lb-ft of torque (519 Nm) and is matched with a Hydra-Matic eight-speed automatic transmission.

The 6.2Lwith DFM — the largest and most powerful gas V-8 in the segment — is SAE-certified at 420 horsepower (313 kW) and 460 lb-ft of torque (623 Nm) and is paired with a Hydra-Matic 10-speed automatic transmission.

Both transmissions feature enhancements designed to improve shift quality, as well as a new centrifugal pendulum absorber torque converter that reduces vibrations to improve smoothness, particularly during cylinder deactivation events.

The engines also feature driver-selectable stop/start technology that helps save fuel in stop-and-go traffic. The 5.3L version is standard in LTZ and High Country models and available on LT, RST and Trail Boss. The 6.2L is available in LTZ and High Country. Both engines will be built at General Motors’ Tonawanda Engine Plant in Buffalo, New York. Active Fuel Management also is employed on the Silverado’s standard 4.3L V-6 and E-85-capable 5.3L V-8.

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