The engine of the 2020 Cadillac CT4-V is a twin-turbo motor in the name of torque.
The 2020 Cadillac CT4-V is one of many turbocharged sport sedans in production today, but Cadillac has tried something few other automakers have done.
The CT4-V uses a dual-volute turbocharger for more torque; Engineering Explained's Jason Fenske has the details.
The CT4-V uses a version of General Motors' L3B 2.7-liter inline-4. As Fenske is quick to point out, GM initially touted the engine's truck-specific design, apparently to allay buyers' wariness of a four-cylinder engine in a full-size pickup.
As the name implies, the engine's dual-volute turbocharger has two volutes, which are passages that circulate air through the turbocharger; the two volutes overlap one another; and the turbocharger's turbocharger has two turbochargers, one of which is a twin-scroll turbo. This is similar in concept to a twin-scroll turbo, but Fenske points out that twin-scroll turbos place the passages side by side.
In GM engines, the dual-volute turbo is combined with an integrated exhaust manifold. This combination helps separate the exhaust pulses from the individual cylinders, improving response. Twin-scroll turbochargers operate on the same principle, but are slightly less efficient, Fenske says.
Twin-scroll turbochargers send exhaust gases to only one side of the turbine, while the dual-volute setup sends exhaust gases to both sides as well. Therefore, the maximum amount of exhaust gas is used to spin the turbine, which allows the turbine to spin more quickly. The dual-volute setup also reduces the distance between the exhaust passage and the turbine, further improving response.
What does this mean in practice? For the Silverado version of this engine, Chevrolet previously announced that if the driver accelerates at 1,500 rpm, 90% of the maximum torque output can be achieved in just 1.9 seconds.
In the CT4-V, this engine produces 320 horsepower and 369 pound-feet of torque, which is sent to the rear wheels or all four wheels via a 10-speed automatic transmission. If that's not enough power, Cadillac also offers a hotter Blackwing version, powered by a 3.0-liter twin-turbo V-6 engine that is expected to produce over 400 hp.