CT6 V-Sport: Cadillac’s biggest track day sport sedan

By Christopher A. Sawyer
The Virtual Driver

(April 16, 2018) The most important thing you need to know about Cadillac’s new 4.2-liter twin-turbo V8 is that a slightly larger displacement version will be offered in the mid-engine C8 Corvette. The only remaining question is whether or not the C8’s version of this new engine will be mated to a dual-clutch transmission (doubtful), a repackaged version of the current C7 manual (possible), or the Cadillac 10-speed automatic stuffed into a transaxle case and fitted with paddle shifters.

Certainly, should Cadillac get its own version of the C8, the last one is the most likely version to be offered, which means it could be the gearbox of choice for the C8.

The 4.2-liter V8 will launch in the CT6 CV-Sport, a high-performance version of Cadillac’s under-appreciated large rear-drive sedan. In that guise, it will produce an estimate 550 horsepower and 627 lb.-ft. of torque, and be joined by a slightly less energetic version pumping out “just” 500 hp horsepower the regular CT6.

As with most new engines, the 4.2-liter V8 is an undersquare design with an 86 mm bore and 90.2 mm stroke. This reduces the weight and size of the pistons, as well as the side force of the piston in the bore, which reduces friction. Not surprisingly, the aluminum block is joined by a forged steel crankshaft, forged steel connecting rods, high-strength aluminum pistons, and cross-bolted main bearings. The compression ratio is 9.8:1.

In order to reduce turbo lag and reduce the engine’s package size, the twin-scroll turbochargers are mounted in the valley of the vee atop the engine, and fed by reversed heads that place the intake ports on the lower outside of the block and the exhaust ports up top. The pair produce up to 20 lb. of boost, and 90% of peak torque is available from 2,000 to 5,200 rpm. Each turbo has an electronically controlled wastegate, throttle body, and heat exchanger.

In addition to the new engine, the CT6 V-Sport sedan is distinguished by its mesh grille, new LED headlamps, lower front aero add-ons, gloss black side window trim, unique 20-in. V-Sport wheels with summer tires, and rear spoiler.

Nineteen-inch Brembo brakes are fitted at each wheel, with the fronts discs clamped by fixed monoblock four-piston calipers. Steering effort has been increased, the Magnetic Ride Control damper and Active Rear Steer settings have been extended for track duty, and the all-wheel drive torque splits revised. The exhaust has been fitted with active valves for less back pressure and a more robust sound, a mechanical limited-slip differential is fitted, and a track mode has been added to the selectable drive modes.

The Virtual Driver