Lexus unveiled a one-off example today of its IS300 luxury sport sedan powered by a 4.3-liter V8 engine from a Lexus GS430. Seeking to demonstrate the potential of the IS300, Lexus commissioned Rod Millen Special Vehicles (RMSV) to build the car. The resulting "IS430" was completed last week at Millen's shops in Huntington Beach, Calif.
"We wanted to explore the performance possibilities of the IS300," said Lexus Group Vice President and General Manager Denny Clements. "The marriage of our 4.3-liter V8 with the sporty IS300 creates a classic muscle car."
The potent V8 engine was paired with a Getrag 6-speed manual transmission and lightweight flywheel, which drive the rear wheels through a stronger limited slip differential and GS430 driveline components.
The concept direction from Lexus required that handling be matched to the high-powered V8 while maintaining reasonable ride comfort and noise levels. TEIN springs and 16-way electronically adjustable shock absorbers work with the original IS300 front suspension in addition to selected GS430 rear suspension components, which help ensure durability against the higher torque of the 4.3-liter V8. Large, sticky Michelin Sport Cup tires on 18-inch Speed Star SSR alloy wheels put the power to the ground.
A similar approach was taken with the cooling system and brakes. A GS430 radiator was fitted to provide ample cooling for the high-output engine. Large Brembo brakes with vented, cross-drilled rotors and four-piston aluminum calipers are there to arrest the newfound acceleration and speed of the IS430.
"The standard IS300 is a robust and well balanced sport sedan, so we thought it would respond well to the additional power of the Lexus V8 engine," said Rod Millen, president of RSMV. "With a package of complementary modifications, it has exceeded our expectations."
Although not a simple conversion, the V8 and 6-speed fit well within the compact IS300 body structure. Curb weight is slightly higher than the standard IS, some of which is due to larger/stronger components needed to deal with the increased performance and some from the new audio/video system.
"Fitting the 4.3-liter V8 and six-speed manual transmission to the IS300 was fairly straightforward," said Millen. "The larger challenge was to develop an electronic interface that would allow the V8 engine to work with the manual transmission and IS300 body - something it was never designed to do."
RMSV's engineering team met the challenge with expertise developed through years of successful racing and building special vehicles for military and automotive clients. They focused on designing the electronics interface while simultaneously working through the mechanical conversion and enhancements. Numerous parts were specifically fabricated for the IS430 including stainless steel exhaust headers and dual exhaust system, transmission adaptor, engine and transmission mounts, air intake system, wire harnesses and fluid connectors.
"Next Generation" Entertainment System Pushing the IS300 performance envelope was not limited to vehicle dynamics. Lexus also wanted to discover the potential of what might be termed a "next generation" in-vehicle entertainment system. Lexus naturally turned to its premium audio systems partner, Mark Levinson, whose system engineers were eager to gain experience with their advanced system development work and receive feedback from users in the field.
The goals for the experimental system were the introduction of a discrete multi-channel 7.1 surround sound experience suitable for automotive use, complete system integration of audio and video, and advancement of sonic performance beyond previous OEM premium systems.
The result of their vision is a 20-speaker/24-channel, 720-watt* audio/video system using a proprietary DVD video player and removable 6.5-inch wide-screen video display. This prototype Mark Levinson system is well suited to the expanded performance of the IS430.
To complete the package, Chip Foose from Foose Design was employed to give the IS430 a more aggressive yet functional appearance. Foose used subtle upgrades including a Rhys Millen Racing front lip spoiler and side skirts with a black over red exterior color scheme that emphasizes the wedge profile of the tightly drawn IS body. A mesh grille and gray headlamp treatment is used up front, and the taillights and rear badging are modified for a simpler look at the rear. Dual exhaust tailpipes not only improve performance, but also help advertise the potent 4.3-liter V8 engine.
The Lexus IS430 is a one-off vehicle built to study of the considerable performance potential of the IS300 luxury sport sedan. There are no plans for a production version.