It seems like only yesterday we were reporting on Cadillac’s all-new 550-horsepower, 4.2-liter, dual overhead camshaft, twin-turbocharged V8 engine destined for the Cadillac CT6-V. Whether this engine sparked the rumors that the C8 Corvette would have a dual overhead camshaft engine, or simply fanned the flames, it definitely lent some credence to the rumor.
However, here we are, almost three years later and the 4.2-liter new hotness is being replaced by the not-really-new hotness. As best anyone can tell, the new 2022 CT5-V Blackwing will be powered by a warmed-over variant of the LT4 engine making a stout 668 horsepower and 659 lb-ft of torque. While there is no precise confirmation of the LT4’s Eaton TVS 1740 supercharger being used on this engine, it only makes sense as that’s what’s already in the production pipeline.
Those specs alone make it the most powerful engine to ever wear the Cadillac crest. It also adds a ton of fuel to the argument that the LT engine is the greatest version of the small-block Chevrolet engine to ever exist. I mean, Cadillac’s newest technological crown jewel engine has just been replaced by a seven-year-old powerplant making over 100 more horsepower… with pushrods no less!
While we don’t have all of the final specs on Cadillac’s new 6.2-liter supercharged engine, Jason Fenske of Engineering Explained does a great job of comparing the two engines with his usual flair and pointing out some pretty interesting things — not the least interesting of which is the timing of the engine’s announcement; only four days after GM dropped the bombshell goal of being all-electric by 2035.
Old vs. New
Fenske starts off by comparing some engine specs. First and foremost is the additional two liters of displacement between the two engines. The larger 6.2-liter engine is boosted by a 1.7-liter Eaton TVS Roots supercharger Fenske guesses will make in the 10psi range, while the 4.2-liter engine has two, twin-scroll turbochargers making around 20psi.
While forced induction has been called the replacement for displacement, displacement plus forced induction is always a winning combination, as evidenced by the supercharged 6.2-liter engine’s rating of 668 horsepower and 659 lb-ft of torque, versus the smaller engine’s rating of 550 horsepower and 640 lb-ft of torque.
That makes for 108 horsepower per liter from the new powerplant, and 131 horsepower per liter from the twin-turbo variant. Both engines feature direct injection with similar compression ratios, but surprisingly the larger engine is an oversquare design, with the traditional LS/LT 4.065-inch bore and 3.622-inch stroke, while the smaller engine has a 3.386-inch bore and 3.551-inch stroke for an undersquare combination.
While commonly held logic suggests that the modern dual overhead camshaft engine should probably spin higher than the “old” pushrod design, that wouldn’t hold true here as the projected rev limit of the new engine is 6,600 rpm like the LT4’s, while the 4.2L twin-turbo engine was limited to 6,000 rpm in the CT6-V.
From there, Fenske dives deep into the differences between the TVS supercharger and twin turbos, specifically the way the CT6-V’s twin-scroll turbos were arranged. For all of that conversation, you’re going to need to watch the video. It’s absolutely worth your time.