CADILLAC CT6’S NEW ENGINE GOES ABOVE AND BEYOND
Twin-turbo V8 four years in the making, but chief engineer keeps mum on further plans
Cadillac has been lobbing fourwheeled grenades at Audi, BMW and Mercedes-Benz for quite some time now, but the Germans have pretty much swatted this American ordnance back from high atop the unassailable peak of Mount Swabia with little effort. This is not to say the V-series cars from Cadillac have not been worthy foes.
Getting the speed and worldclass chassis dynamics has not been a problem for Cadillac. What has been a challenge is creating convincingly well-rounded cars that will lure performance sedan buyers away from the coveted four-rings, blue-and-white roundels and three-pointed stars. But the go-fast engineering lads at Cadillac are nothing if not determined, and this latest volley comes in the form of the 2019 CT6 V- Sport sedan that will go on sale during the first half of next year.
The premium, high-performance sedans of Europe all currently pack small-displacement, twin-turbo V8 engines — Audi and Mercedes-Benz at 4.0 litres, and BMW at 4.4 — all formats that deliver big power, lusty soundtracks, smooth operation and reasonable fuel economy.
Cadillac is answering with a clean-sheet, 90-degree and allaluminum 4.2-L twin-turbo V8. Like the competition, this one uses the “hot V” architecture, stuffing the turbos and catalytic converters within the engine’s V layout, with the intake ports fitted to the outside of the heads where you would traditionally find the exhaust headers. Benefits of this design are compact packaging, along with reduced turbo lag and emissions.
Jordan Lee, chief engineer of Cadillac’s V8 engines, says there’s “a character the premium V8 can embody (that) you can’t get with a V6.” And indeed, the highly pressurized and powerful 3.6-L V6s of latter Cadillac V Series cars delivered the goods, but lacked the “it” factor when it came to refinement and sound.
This V8, which is configured for an all-wheel drivetrain, will come in two states of tune, the most potent kicking out 550 horsepower at 5,700 rpm and 627 pound-feet of torque between 3,200 and 4,000 rpm (90 per cent of that twist is on board at 2,000 rpm). Cadillac is clearly stressing torque here, as it soundly trumps the 553 lb-ft put out by Audi and BMW’s twin-turbo V8s. The Mercedes-AMG 4.0-L engine generates 516 lb-ft in its highest state of tune.
There will also be a non V Sport variant of this V8 “detuned” to 500 hp and 553 lb-ft of torque. There are no mechanical differences between the engines; it’s all in the software, although the 550-hp version gets a sport exhaust system that frees up a few stallions.
“Managing the heat with the turbos and catalytic converters in the valley is probably the most arduous task we’ve faced with building this engine,” John Rydzewski, assistant engineer, says. “We took a good look at what Audi, BMW and Mercedes were doing. They weren’t good enough for us, so we’re developing our own system as we go along.”
Along with liquid cooling, a big part is directing airflow through that hot mess. The twin-scroll turbochargers, which are made of super-lightweight titaniumaluminide, spin to 170,000 rpm and huff 20 psi of air/fuel mixture into the cylinders. The intercoolers cool the intake charge by 74 C.
The V8 also gets a start/stop function, variable valve timing (intake and exhaust) and automatic fuel management that will have it running as a V4 under light loads.
This new V8 will be built in GM’s Performance Build Centre in Bowling Green, Ky. Just like those spectacular AMG engines, each will bear a plaque with a signature of the single technician who assembled it.
Another first for Cadillac, here in the 2019 CT6 V- Sport, will be a 10-speed automatic transmission replacing the eight-speed. This is a high-torque version of the Hydra-Matic unit we’ve seen in the Camaro ZL1.
“You’re going drive this 10-speed and have no idea of how many gears it has,” Mark Kieliszewski, assistant chief engineer for the transmission, explains. “You’re going to be in the right gear at the right time, to be able to deliver this power to the ground in the most efficient and performance-minded way you want to.”
There are paddle shifters if you think you can do it better.
When considering the time and expense that has gone into developing this 4.2-L twin-turbo V8 — the project started four years ago — it’s only natural to assume it will find its way into more than just the CT6 sedan.
I asked Lee if the 4.2 will be the sole V8 in Cadillac’s future, powering both cars and SUVs. His reply? “I can’t speak to future product. But nice try.”
Read into that what you will.
We took a good look at what Audi, BMW and Mercedes were doing. They weren’t good enough for us.