Lexus unveiled a one-off example of
its IS 300 luxury sport sedan powered by a 4.3-liter V8 engine from a Lexus
GS 430 in November 2003. Seeking to demonstrate the potential of the IS 300,
Lexus commissioned Rod Millen Special Vehicles (RMSV) to build the car. The
resulting "IS 430" has since completed its development program with
RSMV and is now road-ready.
"We wanted to explore the performance possibilities of the IS 300,"
said Lexus Group Vice President and General Manager Denny Clements. "The
marriage of our 4.3-liter V8 with the sporty IS 300 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 GS 430 driveline components.
Total Performance Approach
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
IS 300 front suspension in addition to selected GS 430 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 GS 430 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 IS 430.
"The standard IS 300 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
IS 300 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 IS
300 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 IS 300 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 IS 430 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 IS 300 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 IS 430.
Functional Aggression
To complete the package, Chip Foose from Foose Design was employed to give the
IS 430 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.
The dual exhaust system's twin tailpipes not only improve performance, but also
help advertise the potent 4.3-liter V8 engine.
Key Features and Specifications
IS 430
IS 300
Engine:
4.3-liter DOHC V8, normally aspirated
3.0-liter DOHC I6, normally aspirated
Horsepower:
340 (estimated)
215
Torque:
300+
218
Exhaust System:
Custom-fabricated tubular stainless steel headers; dual
hi-flow catalysts and dual low restriction mufflers
Tubular stainless steel headers; dual catalysts; single
outlet
Transmission:
Getrag 6-speed manual
5-speed manual
Driveline:
GS 430
Standard IS 300
Differential:
3.769:1 limited slip
3.727:1 limited slip
Suspension:
Double wishbone with adjustable-height 16-way
electronically adjustable shock absorbers
Double wishbone
Brakes:
Brembo ventilated and cross-drilled 355x32 mm front,
345x28 rear rotors; Brembo 4-piston aluminum calipers
Vented front, solid rear discs: twin-piston front,
single-piston rear calipers
Wheels:
Speed Star SSR 5-spoke aluminum - 18x8 inch front,
18x9 inch rear
17x7 inch 5-spoke aluminum
Tires:
Michelin Pilot Sport Cup - 225/40 ZR18 front, 265/35
ZR18 rear
215/45 R17 front and rear
Curb Weight:
3,350 lbs. (estimated)
3,255 lbs.
Body Components:
Rhys Millen Racing front lip spoiler and side skirts; IS
300 optional rear spoiler
Optional rear spoiler
Paint & Bodywork:
Foose Design/Chris Guinn - solid black over red with
silver dividing pin stripe
Absolutely Red
Audio System:
Mark Levinson® discrete multi-channel with 20 speakers
and DVD video system; 720 watts*, all channels driven; six-disc CD changer
Lexus Premium 4-channel with eight speakers; six-CD
changer
*All channels driven, 20-20kHz, with no more than .01% Total
Harmonic Distortion.
The Lexus IS 430 is a one-off vehicle built to study of the considerable performance
potential of the IS 300 luxury sport sedan. There are no plans for a production
version.
