Understandably, there has been a lot of talk recently about the upcoming 2022 Cadillac CT5-V Blackwing ultra-high-performance luxury sedan, and in particular its supercharged 6.2L V8 LT4 gasoline engine, the most powerful ever fitted to a production Cadillac.
The Blackwing name was previously applied to the twin-turbo 4.2L V8 LTA engine which powered the short-lived, and now discontinued, Cadillac CT6-V. Outrage has been expressed about GM naming a car after an engine it no longer uses, but this is about the same as complaining that the 2021 Chevy Suburban should be called something else because it shares no parts with the vehicle of the same name which went on sale in 1935.
Jason Fenske does not make this point in the video he uploaded to YouTube on February 3rd, but he does provide a useful comparison of the two motors. Fenske’s Engineering Explained channel was created in June of 2011, and has received over half a billion views since then. Its popularity can be explained by Fenske’s talent for giving a great deal of information in an easily understood form, which he once again does to great effect here.
Fenske can’t resist some light-hearted trolling. Early in the video, he quotes from a General Motors press release of January 28th, which stated that the automaker intends to be carbon neutral by 2040, and goes on to say (while failing to suppress an impish smile) that the specifications of the CT5-V Blackwing – very much not a carbon neutral vehicle – were announced just four days later, on February 1st.
With that out of the way, he embarks on a thorough rundown of the CT5-V Blackwing and CT6-V engines, comparing their power and torque outputs, compression ratios, horsepower per liter, configurations, bore and stroke dimensions and maximum revs. Among other things, he notes that the CT5-V Blackwing’s engine is considerably stronger, producing 668 horsepower and 659 pound-feet of torque against the CT6-V’s 550 horsepower and 640 pound-feet of torque.
Fenske does not consider this a failing of the LTA. To the contrary, he later says that GM engineers “could probably crank up the boost if they wanted to.”
In fact, Fenske notes that although the LTA is no longer in production, it first appeared for the 2019 model year, long after the LT4 made its debut in the 2015 Chevy Corvette Z06. The basic design of the LTA is also more modern. It has twin overhead camshafts operating four valves per cylinder, while the LT4 is a pushrod unit with only two valves per cylinder, a layout first used in the late 19th century.
Despite that, the LT4 had a rev limit of 6,600 rpm in the Z06 (and 6,500 rpm in the CT5-V Blackwing) compared with the 6,000 rpm of the LTA. This is less of a paradox than it might appear. The 4.2-liter LTA is an undersquare engine with bore and stroke measurements of 3.39 inches (86.0 mm) and 3.55 inches (90.2 mm) respectively. The 6.2-liter LT4 is oversquare, and therefore inherently more capable of higher revs, at 4.06 inches (103.25 mm) and 3.62 inches (92 mm).
Fenske also praises the LTA engine’s efficiency. The CT6-V was marginally more economical than the CT5-V Blackwing even though it was a heavier vehicle with a more complex drivetrain, sending power to all four wheels rather than just the rears.
It is, of course, impossible to question the power of the CT5-V Blackwing, which is superior to that of the obvious European rivals – the Audi RS 7 Sportback, the BMW M5 and M5 Competition, the Maserati Ghibli Trofeo and the Mercedes-AMG E 63 S – all of which have an MSRP at least $19,000 higher.
All the same, Fenske indulges in one more piece of trolling near the end of the video. “The company will also continue to increase fuel efficiency of its traditional internal combustion vehicles,” he quotes, before adding, “Or not. Whatever.” Check out the video here:
This post was created in collaboration with our sister publication, Cadillac Society.