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CORVETTE TODAY #164 - My Trip To The Amelia Island Concours

In March of this year, your CORVETTE TODAY host, Steve Garrett, attended the unveiling of the three 1960 Cunningham Corvettes from Le Mans at the Amelia Island Concours. Steve recaps his weekend at Amelia Island and all the events that took place during the show!;
The Cunningham Corvettes were the hit of the entire weekend and you'll hear about the whole story on this episode of CORVETTE TODAY.
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Sigala Back As MECF Venodr

What is new? For MECF members, has developed a new customer communications system, trained more staff, and with some inducements is committed to providing your products along their stated completion timelines.
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CORVETTE TODAY #163 - Corvette News & Headlines, Late May 2023

Recognizing Memorial Day, there is still a lot of news coming out in the world of Corvette! Keith Cornett from CorvetteBlogger is back on the show with your CORVETTE TODAY host, Steve Garrett, to detail all the important things happening with America's Sports Car.;
Here are a few of the topics covered by Steve and Keith on this week's show:
1. Engineers are spotted in what we think is the C8 ZR1 prototype
2. We have two new E-Ray videos available
3. New Z06 allocations went out in the middle of this month (May 2023)
4. The National Corvette Museum names a new Marketing Director
5. Australia recalls the 2022 C8 Corvette for being too loud
6. Did GM's Instagram page give us a C9 Corvette preview?
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2023 Corvette Info Including E-Ray, SR & Z06 Pricing, SR & Z06 Visualizers, 70th Anniversary Info, Press Releases for SR & Z06 & Their Build & Price, Order Guides & Visualizers

2023 Corvette Brochure:
E-Ray Visualizer:
Official E-Ray Press Release: https://www.midenginecorvetteforum.c...-press-release
Official GM E-Ray Pictures: https://www.midenginecorvetteforum.c...and-visualizer
+ 25 KEY E-Ray Components/Factors:
E-Ray Leaked Info/Visualizer: https://www.midenginecorvetteforum.c...tte-e-ray-leak
Z51 & Z06 GM Track Specs: https://www.midenginecorvetteforum.c...ecommendations
Z06 Order Guide:
Z06 MSRP and Options Pricing: https://www.midenginecorvetteforum.c...freight-charge
2023 SR Build & Price: https://www.midenginecorvetteforum.c...up-and-running
*2023 SR & Z06 Official Owners Manual:; and,
* 2023 GM Bash Major Seminar with HQ video: https://www.midenginecorvetteforum.c...ore-bash-video
*2023 Stingray Visualizer:
*2023 Stingray (ONLY Order Guide:
*70th Anniversary Combined Press Release For SR & Z06: https://www.midenginecorvetteforum.c...iversary-model
*Z06 Press Release: https://www.midenginecorvetteforum.c...-press-release
*Z06 Reveal Pictures: https://www.midenginecorvetteforum.c...eveal-pictures
*Z06 Visualizer:
Order Guide (unofficial): https://www.midenginecorvetteforum.c...-action-center
*Z06 vs Z07 Aero Components: https://www.midenginecorvetteforum.c...s-similarities
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GM New Cylinder Deactivation System

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  • GM New Cylinder Deactivation System

    Originally posted by GMTechLink
    New V8 Engines Feature Dynamic Fuel Management

    Originally posted by GMTechLink
    Posted on August 30, 2018 by blogadmin

    The all-new 2019 Silverado 1500 and Sierra 1500 offer two new V8 engines: the 5.3L V8 (RPO L84) and the 6.2L V8 (RPO L87). (Fig. 1)

    Fig. 1

    These new engines deliver the power demanded by truck owners — the 5.3L V8 has a power output of 355 horsepower and 383 lb.-ft. of torque and the 6.2L V8 (Fig. 2) develops 420 horsepower and 460 lb.-ft. of torque — while optimizing fuel economy.

    Fig. 2

    One of the enhancements to the efficiency of the new engines is the new Dynamic Fuel Management (DFM) system, which is the successor to Active Fuel Management (AFM). AFM alternated between 8 cylinder and 4 cylinder modes, but DFM actively turns off any number of cylinders in a variety of combinations, allowing the engine to run on 17 different cylinder patterns.

    DFM is powered by a sophisticated controller that continuously monitors the vehicle’s accelerator pedal and runs a complex sequence of calculations to determine how many cylinders are required to meet the driver’s power demand. The DFM controller can make this determination 80 times per second. Switching between V8 and DFM modes is accomplished in less than 250 milliseconds, or within two revolutions of the crankshaft, making the transition seamless and transparent to the driver.

    Valve Lifter Operation

    Cylinder deactivation is accomplished by not allowing the intake and exhaust valves to open on the selected cylinders by using special valve lifters. (Fig. 3) The deactivation lifters contain spring loaded locking pins that connect the internal pin housing of the lifter to the outer housing.

    Fig. 3

    When cylinder deactivation is commanded, the ECM will determine what cylinder is firing and begin deactivation on the next closest deactivated cylinder in the firing order sequence. Although both intake and exhaust valve lifters are controlled by the same solenoid, the intake and exhaust valves do not become deactivated at the same time. Cylinder deactivation is timed so that the cylinder is on an intake event.

    During an intake event, the intake cam lobe is pushing the valve lifter upward to open the intake valve against the force of the valve spring. The force exerted by the valve spring is acting on the side of the lifter locking pins, preventing them from moving until the intake valve has closed. When the intake valve lifter reaches the base circle of the camshaft lobe, the valve spring force is reduced, allowing the locking pins to move, deactivating the intake valve.

    When cylinder deactivation is commanded on, the exhaust valve for the deactivated cylinder is in the closed position, allowing the locking pins on the valve lifter to move immediately and deactivate the exhaust valve.

    When all enabling conditions are met for cylinder deactivation, the ECM will actuate the high and low control of each solenoid control circuit in firing order sequence, allowing current to flow through the solenoid windings. With the coil windings energized, the solenoid valve opens, redirecting engine oil pressure through the valve lifter oil solenoid valves into 16 separate vertical passages in the engine lifter valley. The 16 vertical passages — two per cylinder — are connected to the valve lifter bores of the cylinders to be deactivated.

    When operating conditions require a return to V8 mode, the ECM turns off the control circuits for the solenoids, allowing the solenoid valves to close. With the solenoid valves closed, engine oil pressure in the control ports is exhausted through the body of the solenoids into the engine block lifter valley. The oil passages of the valve lifter oil solenoid valves incorporate several bleeds in the oil passages to purge any air trapped in the engine block.

    Valve Lifter Oil Solenoid Valve Operation

    DFM uses eight valve lifter oil solenoid valves (one for each cylinder) that are mounted in the engine block valley under the engine block valley cover. (Fig. 4) Each solenoid controls engine oil pressure to the intake and exhaust valve lifters on the cylinders selected to deactivate. Engine oil pressure is routed to the lifter oil gallery from an internal oil passage on the rear of the cylinder block.

    Fig. 4

    When an oil control solenoid valve is commanded open, pressurized oil forces the lifter locking pins (Fig. 5, E) inward. The pushrod (Fig. 5, A) remains in a constant position and does not travel upward and downward. The outer body of the lifter (Fig. 5, C) moves upward and downward independently from the pin housing (Fig. 5, D). The valve lifter spring (Fig. 5, B) retains tension on the valve train components to eliminate valve train noise.

    Fig. 5

    With DFM, the engines are able to better balance power needs with fuel efficiency. During an industry-standard test schedule, the 2019 Silverado 2WD with the 5.3L V8 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.

    – Thanks to Dave MacGillis and Sherman Dixon

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  • #2
    Mechanically, it sounds pretty much the same as AFM (just on more cylinders). The major change seems to be the software that determines when, how many, and which cylinders to deactivate.
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    • #3
      Thanks for posting this John - I really enjoy these tech articles.

      I expect we'll see this tech on the LT1+ (the LT11?) in the 2020 ME Corvette.

      Hopefully we'll have a disable switch, or perhaps this system will only be active when driving in ECO Mode.

      I thought it curious that there was no mention of how much fuel economy is improved with this system (versus AFM)...
      Last edited by Mobius; 08-31-2018, 12:28 PM.
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