Including AFM Tech in the C8 Corvette ZR1’s LT7 V8 is a Huge Mistake

General Motors commodities are planned more than five years in advance. They are the product of careful coordination between more than 160,000 global employees, not to mention partnerships with a massive dealership network, countless suppliers, and all of their respective employees. A ship that size floating in the sea of the modern information age is bound to suffer from some leaks. This is especially true when you consider the prying eyes of spy photographers, curious journalists, and other interested parties – which, in the Corvette’s case, includes an army of rabid fans who, by and large, are all successful, motivated people with a lot of time on their recently-retired hands. Add all of this up, and it is no surprise that these ‘Vette specialists struggle to remember the last Corvette debut where anything but the final numbers was a surprise. Now, we wouldn’t hesitate to believe a conspiracy theorist who claims most of these leaks happen by design as a way of keeping the fire burning in the furnace of the hype train. Still, even if that’s the case, GM has struggled mightily to keep the details of its most anticipated products secret before their respective debuts and obviously didn’t want ALL of the info we’ve obtained in the past decade-plus to get out.

Case in point: we’ve had Chevrolet’s entire eighth-generation Corvette playbook since April of 2020, and, except for some COVID-related delays, it hasn’t been wrong once. Because of this, we know the C8 ZR1 is the next model up to bat – its imminent unveiling has been confirmed by a year of public prototype testing. One of the biggest ZR1 leaks of 2023 came to us by way of the sleuths at our sister site MidEngineCorvetteForum.com, who uncovered detailed references to the ZR1’s presumed “LT7” V8 powerplant in GM’s own parts catalog. The big headline from this particular unplanned flow of information was the revelation that despite sharing its displacement with its forthcoming sibling, the Z06 and its 180-degree crank are to remain a unique proposition in the Corvette portfolio; the ZR1’s 5.5 will feature a traditional cross-plane crank.

Now, in the months since that major leak hit the ‘net, we’ve been waiting for additional information regarding one of its role players – namely, GM’s inclusion of Active Fuel Management (AFM) technology in the ZR1’s twin-turbo LT7 V8. Thus far, the only word to come down was an April Fools-style change to said catalog that retconned the LT7 into a 4.3L diesel – but there’s been nothing serious for us to sink our teeth into. This is curious because any false association with AFM should have sent the Corvette team pouring into the streets to shout down such slander, but their silence on the matter speaks volumes. If AFM does indeed find its way into the ZR1’s 850-ish horse engine bay, it’ll likely spell trouble.

Why AFM is Bad News, especially for the C8 ZR1

Photo Credit: Spiedbilde

In the last 20 or so years, only two possible outcomes can result from the automotive industry kowtowing – either on its own or at the behest of the world’s governments – to the climate crazies among us. The first involves a downgraded product with significantly decreased longevity and reliability that conspires to inconvenience and/or annoy its end users. Prime examples of this include, but aren’t limited to, such “technologies” as Auto Start-Stop, Diesel Exhaust Fluid/Particulate Filters (why a good 2006-07 LBZ Duramax still commands close to MSRP), and one that hits close to home for Corvette faithful: the dreaded Skip Shift “feature.” Outcome two is the disastrous miscalculation best exemplified by the forced transition to an electric future (devastating for the business from a money-making standpoint, bad for consumer choice, and bad for capitalism, in general) and Europe’s long-time push for its citizens to purchase “clean diesels” (which led to “Dieselgate” and an estimated 50,000 dead Europeans per year (we can partially thank GM for ensuring that diesel commuter cars never caught on here!)).

AFM lands somewhere in the middle and you might also know it as “Displacement on Demand” or “Cylinder Deactivation.” It has struggled with branding – as underperforming equipment tends to – since it debuted as a fuel-saving measure in 2003 models equipped with the 5.3L V8. Like most concepts outlined in the previous paragraph, AFM makes a lot of sense on paper. It allows a brawny V8 to turn into a fuel-sipping four-banger during cruising and other low-rpm conditions. Sadly, this imagined “best of both worlds” scenario turned into a “not being able to have one’s cake and eat it too,” situation in practice.

Since its inception, Active Fuel Management has been a black eye on an engine family that has proven to be all but indestructible since it first hit the scene in 1955. Do a Google search for “afm issues,” and you’ll get more than 21,000,000 results. Searches, including the tech’s other two designations, return an additional 33.3 million unique pages! Main themes within these results range from excess oil consumption to catastrophic cam and lifter damage. A popular Reddit thread poses the question, “Has anyone had an AFM system that didn’t cause engine problems?” [cleaned up for clarity], even without the added difficulty of managing the kind of power that the C8 ZR1 will be dealing with, AFM V8s have been widely labeled “ticking timebombs,” and the technology already finds itself at the center of multiple Corvette-centric lawsuits against General Motors; not exactly what you want to hear when you are thinking about plunking down $200,000 (or more!) for a luxury good.

The Worst Part/We’ve Been Here Before

Photo Credit: Kevin Bayerlein / C8 Corvette Owners (FB)

It makes no sense for GM to risk including such an iffy technology in a vehicle designed for maximum performance with a customer base where roughly 0.0% of its members give fuel economy a second thought. Couple the LT7’s likely record amount of power/twist with the fact that the Corvette Team is also taking its first foray into turbocharging in the ZR1, and the AFM juice not only doesn’t seem to be worth the squeeze; it looks like the fuse on an already volatile powder keg.

You would think that GM learned its lesson with the eight-speed automatic transmission that was forced into duty in the C7 Z06. Based on how swiftly that unit was replaced in applications ranging from the Camaro (RIP) to the GMC Yukon the miunte the superior 10-speed auto was completed, GM knew that the 8-speed wasn’t up to snuff. Yet, the powers that be still insisted on installing the 8-cog slushbox in The General’s halo car in spite of no established precedent of offering an auto in a prior Z-branded ‘Vette in the first place. This ill-advised decision led to more lawsuits and, worse, earned the otherwise monstrous Z06 ill repute as an on-track overheater, so why, oh why are they crossing the same shaky bridge over alligator-infested waters once more!? The whole thing boggles the mind!

Before we close, though, it’s worth acknowledging a few counterpoints:

• Nothing about the ZR1 or its LT7 is set in stone at this point; it’s entirely possible that we are worrying for nothing.
• Every Corvette motivator is lovingly pieced together at the Performance Build Center in Bowling Green and they have suffered considerably fewer AFM problems than their mass-produced counterparts (so all of this might all be a bit overblown like the LS7 valve guide stuff – but don’t you think a big deal should be made of all possible issues when you are talking about something with so much riding on it that is also going asking such a significant investment from buyers?).
• There’s no engineering team we’d trust to make the Corvette+AFM combination feasible over the guys that recently delivered a (so far) reliable 5.5L (when Ferrari never dared to exceed 4.5L) flat-plane V8 that surpassed the output of the previous record-holding NA V8 by a whopping 50 ponies!

Here’s hoping they can pull off another miracle – but all we’re saying is that they’ve got their work cut out for them, and the reputation of America’s Sports Car is on the line – no pressure, right?

Related:
GM Parts Catalog Leak Confirms the C8 ZR1’s LT7 is a 5.5L Turbo V8 with VVT and AFM Technologies
GM’s Disinformation Campaign Now Reports the LT7 Motor is a 4.3L Diesel
RUMOR: First EX-VIN 2025 Corvette ZR1 Completed at Bowling Green

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