Inside Bentley’s New 4.0L Twin-Turbo Flying Spur V8 Engine

When you think of “Bentley” you think of plush opulence. You probably think of prim and proper, “Do you have any Grey Poupon”-esque vehicles. However, Bentley has also always made sure its elegance has the matching performance. It’s one thing to build a rowdy engine with the power and no manners. It’s another category entirely to make copious amounts of power with impeccable table manners and refinement.

Many performance enthusiasts might scoff at “only” 550 horsepower out of a twin-turbocharged V8 engine, especially considering the vehicle’s 5,100-plus-pound curb weight. However, 550 horsepower from an efficient, refined engine combination is impressive no matter how you slice it.

Starting with a five-bearing aluminum block, the bores are lined with a plasma spray arc coating measuring only 150 microns thick. The Flying Spur V8 was designed as a square engine with an 86mm (3.386-inch) bore and stroke to equate to an even 4.0 liters (244 cubic inches) of displacement.

The key to the Flying Spur V8’s grunty low-end while still being able to make power at 7,000 rpm are the two twin-scroll turbochargers, each capable of an astonishing 176,000 rpm impeller speeds.

A direct injection fuel system combines with a centrally mounted spark plug and tumble-port dual-overhead-cam four-valve cylinder heads to make for a more thorough combustion event. In order to keep the emissions clean, the engine is fitted with a camshaft phasing system capable of 50 degrees of adjustment, along with cylinder deactivation mode which disables four cylinders to make a “perfectly balanced” V4 engine configuration.

A key component to the engine’s efficiency is the dual, twin-scroll turbochargers mounted in the valley of the engine, for a “hot-V” configuration. The turbos make just over 23 pounds of boost and have an astounding 176,000-rpm impeller speed. Taking advantage of the 1,700-plus-degree exhaust gas temps, the unit’s catalytic converters are also nestled between the cylinder heads to increase their efficiency.

All of that combines for an output of 542 horsepower and 568 lb-ft of torque, available from 2,000 rpm through 4,500 rpm, with a peak engine speed of 7,000 rpm. That measures out to just over 135 horsepower-per-liter or 2.22 horsepower-per-cubic-inch. While that might not set any records, you’d be hard-pressed to find an engine making similar power in such a refined manner.

One of the design goals of the Flying Spur V8 engine program was an overall compact engine package. Getting a 4.0L twin-turbo dual overhead cam engine into a minimal footprint is no small feat, but Bentley has done it.

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About the author

Greg Acosta

Greg has spent fifteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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