Bentley Motors 2007 Arnage Achieves LEV2 Emissions Compliance With Improved Performance

08 September 2006


Integral Powertrain supports Bentley Motors in achieving LEV2 emissions
compliance and improved performance for its 2007 Arnage model.


Engine technology specialist Integral Powertrain has worked with Bentley
Motors on a major emissions and performance upgrade for the 2007 Model
Year Arnage model. IP used its advanced simulation technology to provide
Bentley with an analysis to enable the development of a more powerful
and responsive version of its mighty 6.75 -litre V8 engine that now
meets the most stringent global emissions regulations, without the need
for unusual or complex aftertreatment.


The Bentley Arnage is the quintessential British luxury car, but
underneath its classic, restrained styling, the Arnage is a highly
sophisticated vehicle that is constantly evolving to meet the demands of
its owners.

Among the challenges faced by Bentley's engineers was the need to meet
demanding US emissions regulations, while delivering effortless
performance and driveability. The 2007 MY Arnage now meets CARB LEV-2 as
well as Euro Stage 4 emissions standards, while producing 500bhp and
1000Nm of torque.

"We have worked with Bentley on a number of projects over the past five
years," explains John McLean, IP's head of powertrain controls, "So we
had demonstrated our ability to tackle challenging engineering projects
and deliver solutions that have met its extremely demanding standards.
We're proud that Bentley trusted us to support it with these major
upgrades to the Arnage's engine and delighted to have helped deliver
such an impressive result."

IP worked with Bentley's engineers to specify a pair of improved
turbochargers which, together with the Arnage's new 6-speed
transmission, enhanced the Arnage's throttle response.

"We are pleased with the improvements to performance and responsiveness
delivered to the Arnage," said Roger Duckworth, IP's head of engine
development. "The changes should be immediately noticeable to Bentley's
customers."

To meet one of the world's most demanding emissions standards in a 6.75
-litre, V8-powered vehicle weighing 2585kgs, IP employed its armoury of
sophisticated simulation methods. Control system simulation and
model-based calibration tools were used to optimise vehicle driveability
and emissions performance. To comply with stringent engine misfire
monitor legislation, dynamics simulation tools were used to revise the
Bentley engine's valvetrain, improving its performance.

"There was concern that the LEV-2 legislation might require a
fundamental re-design of the vehicle's emissions aftertreatment system,"
explains McLean. "We demonstrated that it was possible to meet the
targets with an improved engine control calibration and coating of the
catalysts, while boosting the effortless power that is a hallmark of the
brand."

While Bentley's engineers were confident that the Arnage's V8 could be
adapted to meet LEV-2 standards, IP was able to prove the project's
feasibility, using advanced control technology and relatively
conventional exhaust catalysts. A key challenge had been the control of
catalyst light-off after engine start. Despite the presence of turbine
housings in front of the catalysts, the team's strategy ensured that the
catalysts became operational only 17 seconds after starting the engine
and achieved 95 per cent conversion efficiency in just 30 seconds.


The Arnage V8 is now set to continue its long history of powering
Bentley's most prestigious products for many years to come and Integral
Powertrain is proud to have been part of the team that achieved this
major milestone.