For engineer Steve Moore, the most difficult days of the Bentley Red Label Arnage test program came late last March.
The problems began when the ice started to melt during a premature spring thaw in Arjeplog, Sweden.
Moore, a development engineer for chassis systems for Rolls-Royce and Bentley Motor Cars Ltd., needed firm ice on the frozen lakes to finish cold-weather testing of the prototype of the Red Label Arnage sedan.
If the lakes thawed too soon, Moore couldn't take the prototype vehicle out to finish the final cold-weather validation. Then Bentley would have had to wait for another winter for final testing. That would have meant the car would miss its scheduled world debut at the Frankfurt auto show last month.
'We were really up against it,' Moore said. 'We did really worry. You'd contact people back at Crewe (headquarters for Rolls-Royce and Bentley), but it was hard to get them to understand how the lakes melt. It's on the nature programs, and it's really true.
Fortunately, the cold weather lingered so Moore could get the car back out on the frozen lakes early in the morning to finish the tests.
It was a nerve-wracking finish to a very intense few months for Moore and a team of engineers at Rolls-Royce and Bentley, Robert Bosch GmbH and Zyteck Automotive Ltd.
When Bentley engineers received approval to retrofit the 40-year-old 6.75-liter V-8 engine into the Arnage sedan last October, they knew they had a challenge on their hands.
TOO HIGH, TOO LONG
The big V-8, also used in the Bentley two-door model, was too high, too low and too long for the Arnage engine bay. The bay had been designed to accommodate the 4.5-liter BMW engine that until now has powered the range.
That BMW engine had been hailed as the Bentley engine of the future when it was introduced less than two years ago. But that was before Rolls-Royce and Bentley Motor Cars Ltd. was sold to Volkswagen AG in summer 1998 and before the Rolls-Royce marque was acquired by BMW after a series of legal maneuvers.
VW Chairman Ferdinand Piech, senior VW officials and Bentley management felt the BMW engine did not have enough torque to satisfy some Bentley customers. And poor initial sales in some key areas, most crucially Bentley's home market in England, seemed to support that view.
The Bentley engine of the future, known as the W16, would not be ready for several years, so stopgap measures were necessary. Backed by VW's engineering resources, they decided they might be able to use the old pushrod V-8 after all.
Perhaps the most challenging task engineers faced had to do with the electronics needed to make the engine talk to the rest of the car, most importantly the traction control system. The Arnage's communications architecture network was designed by Bosch to talk to the Bosch engine management system on the original 4.5-liter BMW engine. But the engine management on the 6.75-liter engine was supplied by Zyteck, a company in Sutton Coldfield, England. That meant engineers had to make two incompatible engine computer systems talk to each other - and do it in about half the usual time.
'We did not have two winters available to us,' said John McCallum, project director for the Bentley Arnage and Rolls-Royce Silver Seraph.
The risk was that the system would not work with the heavier, more powerful 6.75-liter engine, thus delaying the project or causing it to be canceled.
'They had a lion to tame,' said McCallum, describing the big 400-hp engine.
Traction control was the trickiest piece of the puzzle. What engineers needed was a system that would allow the enthusiast Bentley driver to drive the car hard but that would also help keep the big sedan out of trouble in an emergency or in winter conditions, Moore said.
'The important thing was to make sure car systems could communicate and still be controlled,' McCallum said.
To get it right, they needed to go where the weather was cold. A prototype was built and taken to the frozen lakes around Arjeplog.
After initial calibrations, the car then was taken to Germany for more tests at Bosch's test track in Boxberg. There, a secondary throttle, operated by a motor, was installed to take over control of the engine when the traction control kicked in.
The white test car then returned to Arjeplog for another month of cold-weather testing and calibration. Final dry-pavement testing was done on mountainous public roads around Corvara, Italy, in the Dolomites.
VW and Bentley management signed off the car in Wolfsburg last August. The Red Label Arnage made its scheduled appearance in Frankfurt as planned, much to the relief of Steve Moore, who remembers all too well the thaw that almost stopped the big car in its tracks.