Bentley’s Mighty W12 Bacalar Engine Passes Test Program

Paul Myles

TU-Editor

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18th February 2021

Bentley’s new 6.0-liter W12 TSI engine destined to power its forthcoming Bacalar model has passed its exhaustive bench testing ready for production.

The motor, producing a claimed 650bhp and 667ft-lbs of torque, also claims to be the most advanced 12-cylinder engine in global production. Since the first introduction of the twin-turbocharger W12 in 2003, the refinement of the engine has seen an increase of up to 27% in power, 38% in torque and a reduction of 38% in emissions.

The W12, first used in WW1 aircraft, has been a stalwart of Volkswagen Group performance products since 2001 and found its way into the Bentley brand the following year. The W-configuration means that the engine is 24% shorter than an equivalent V12 with obvious advantages.

This latest generation boasts a crankcase 30% stronger than its predecessor, while the cylinder surfaces were coated to reduce friction and improve corrosion resistance. A low-alloy steel coating is applied to the bores using an atmospheric plasma spray process. Improvements were also made to the cooling system, with the engine featuring three separate coolant circuits. The first is designed to bring the cylinder heads up to optimum operating temperature as quickly as possible boosting performance and reducing emissions. The second cools the engine block and oil system, while the third handles the thermal load of the turbochargers. Each system has a dedicated water pump.

The W12 combines high-pressure direct fuel injection, at 200 bar, with low-pressure port injection at 6 bar. The system claims increased refinement, lowers particulate emissions and enhances power and torque delivery. Twin-scroll turbochargers are employed and the exhaust assemblies for the three front and three rear cylinders are separate from one another which then feed the impellers. The turbocharger housing is welded directly to the exhaust manifolds and features integrated speed sensors.

Bentley’s variable displacement system shuts down half of the engine under low loads. Intake and exhaust valves, fuel injection and ignition are all shut down on defined cylinders, with the engine running as a six-cylinder for improved efficiency. The system will run in this mode in gears three to eight, below 3,000 rpm and up to 221ft-lbs torque output.

— Paul Myles is a seasoned automotive journalist based in London. Follow him on Twitter @Paulmyles_