AG is surging ahead in the horsepower race in its quest for a place in the premium-vehicle market alongside the likes of German rivals Mercedes-Benz AG and AG.
Now on the starting grid is an upgraded W-8 engine for a range-topping Passat and a massive W-16 for a new, future Bugatti. Both are derived from VW's compact VR (German acronym for “vee in-line”) design, where two staggered cylinder banks are separated by a narrow 15-degree “vee” angle — delivering a possible benchmark in mechanical energy density.
Unveiled as a pilot project several years ago, the W-8 has had its displacement increased from 3.7L to 4L (3,999 cc). Although the original 275-hp at 6,000 rpm power output is retained, peak torque is boosted to 273 lb.-ft. (370 Nm) at 2,750 rpm. The twin 15-degree cylinder banks are set at a 72-degree angle and there's a 4-valve layout operated via roller followers by a pair of chain-driven camshafts, both with variable timing, for each bank.
The crankshaft has a “flat” 180-degree pin configuration for sporty performance, with any rough spots smoothed by twin balance shafts. A specially-tuned exhaust system with a sonorous note gives voice to the competitive image. All auxiliaries are driven by a single double-sided belt. The compact design keeps the engine length down to 16.5 ins. (42 cm) and both height and width to roughly 27.5 ins. (70 cm), making the W-8 an easy fit for transverse front-drive installation.
Standard transmission for the Passat W8 is a 6-speed manual gearbox, though a 5-speed Tiptronic-style automatic is an option. And there is the permanent all-wheel drive system that VW calls 4Motion; for the Passat W8 a Torsen-made central differential is combined with four electronically controlled Haldex couplings (see WEVTU — July 15, '98, p.5), together with an electronic stability program (ESP) and traction control (TCS).
With this sophisticated drivetrain providing the ultimate in all-weather traction, the top Passat is credited with a 0-to-60-mph (0-97 km/h) time of 6.2 seconds and a top speed of 155 mph (250 km/h).
Bugatti as an auto pioneer dates back to 1901, when the first cars appeared, with serious production soon starting at a plant near Strasbourg, France. Vehicles powered by engines with as many as 16-cyls. followed, as did racing successes and sports car fame. This continued until 1939 when the war ended production, and all post-war attempts at a company revival failed.
In 1998, the VW Group acquired rights to the marque, and created Bugatti Automobiles S.A.S. as a satellite company. VW presented various concept cars at several international motor shows, but only now has decided on the EB 16.4 Veyron as a production model. This super sports car is named after the racing driver Paul Veyron, noted for many pre-war Grand Prix wins.
As a mid-engined 2-seater, the ground-breaking Bugatti has a powerplant of Formula One potential. With 8L capacity and direct injection, it develops no less than 1,001 hp at 6,000 rpm and an incredible torque of 923 lb.-ft (1,250 Nm) from 2,200 to 5,500 rpm. The engine might be designated as WW-16, as there are essentially two W-8s joined in a vee formation. It was first exhibited at the 1999 Geneva Motor Show in the prototype Bentley Hunaudieres and seen as a possibility for future Bentleys made at the Crewe, England, factory, now also under VW control.
Output of a “mere” 623 hp was increased by 60% for the latest engine — and torque by even more. This was achieved primarily through turbocharging. There are four exhaust-driven blowers, two per cylinder bank, each fed from four cylinders. Charge air from each pair is piped through individual water/air intercoolers mounted on the cylinder heads, and from there to adjoining inlet manifolds. A nine-bearing crankshaft carries two opposing connecting rod big-ends on each of the eight pins.
Boost pressure is 16 psi (1.1 bar) and compression ratio 15 9:1. Engine management is handled by an electronic master-slave system, with two independently functioning computers per cylinder bank controlled by a central ECU.
The prototype W-16 pictured has a 72-degree vee angle, which will be increased to 90 degree in production to reduce crankshaft and main bearing loading. This 16-cyl. engine apparently sidelines the proposed W-18 (with a different cylinder configuration), which has been temporarily shelved for future horsepower adventures.
Permanent all-wheel drive is an essential match for the immense torque delivery. Fitted longitudinally behind the cockpit, the engine has the rear axle differential flanged to the back of the crankcase. This is driven by a long quill shaft from the 6-speed manual gearbox mounted on the front of the crankcase. A power takeoff (PTO) couples to the propshaft for the front differential.