Factory Hot Rods: Lexus IS 430

Every enthusiast understands the truth in the saying "always get the bigger engine." If you're a real car geek, there's never any question about which way to go when it comes time to make that decision. But that isn't the case with the Lexus IS 300. There is no bigger engine.

Yet.

Lexus is careful not to admit the production possibility of a small V8-powered sedan that has obvious crosshairs on cars like the Audi S4 and BMW M3. But the simple fact is Lexus wouldn't commission a car like the IS 430 if there wasn't someone thinking about its production potential in the U.S. market. The job of marrying the IS 300 chassis, GS 430 engine and Toyota Supra transmission, clutch and rear end, fell in the hands of Rod Millen Specialty Vehicles. Millen and his company have a longstanding relationship with Toyota and are known for their ability to create outrageous show cars as well as capable racecars. And it shows in the IS 430.

Romp the throttle and the IS emits a throaty rumble that initially seems out of place coming from a Japanese sedan. Its sound is low and smooth--American in tone but Japanese in frequency. Completely unique. It's visually striking as well. Chip Foose Design and Chris Guinn coated the IS 430 in a spectacular red and black paint scheme that complements its distinctly Japanese shape. Eighteen-inch SSR wheels and huge Michelin Pilot Sport Cup tires completely fill the fenders. Bottom-line first impression? One mean IS.

But looks and sounds are second to performance. It's on the street and on the track that the IS 430 would make its strongest impressions, particularly when measured against the O.E. levels of refinement found in the IS 300 we brought along for comparison.

With 4.3-liters of overhead cam muscle motivating roughly 3,200 pounds of sedan, the IS 430 makes some stomp on the street. Light into the throttle from a standstill and you'll quickly make friends with the good folks at Michelin as you leave a 265mm-wide footprint for 30 or 40 feet. It certainly doesn't lack power. Trouble is, the electronic throttle carried over from the GS 430 was calibrated to work with an automatic transmission and combines with a rather unintuitive clutch engagement to make the car hard to get moving smoothly.

High revs and a sloppy clutch dump are actually the easiest ways to get the car rolling, which is fine if you're editor Oldham. His whole world revolves around the burnout. But if you live in a neighborhood infested with home owner's association Nazis, burnouts aren't your first priority. We executed careful footwork when necessary.

Still, it's not a slow machine. Once you've got your head around the throttle, clutch and power delivery of a big motor in a small car, you can focus on the chassis. Suspended by Tein Flex coil-overs we expected a harsh ride. But with 16-way adjustability there was a large range of ride quality available. Achieving a comfortable street ride was easy, but damping, particularly in the rear, always seemed a bit hard to control.

We had fun in the IS 430 on the street. It sounds awesome, is comfortable and reasonably quick, does huge burnouts on demand and has the best stereo we heard in any car. Admittedly, our ears are better trained to hear detonation under high boost than to evaluate Mozart's Fifth through the 720-watt Mark Levinson 20-speaker system in the IS 430, but it sounded good to us. Really good. Good enough that we actually sat in the car for the sole purpose of listening to music, which is saying something since everyone around here knows cars are for powerslides.

On the track, our impressions about the IS 430 were concreted. The monster sedan rewarded wheelspin in the quarter mile, producing better times with lots of slippage. We thought it would run in the 13s, but the staggering out-of-the-hole power was slightly deceiving as the IS 430 didn't meet expectations on the high end. Best it could manage was a 14.0-second time at 100.1 mph. Still, that's 1.3 seconds better than the stock IS 300 we tested. Sixty miles per hour came and went in 5.1 seconds, 2.2 seconds better than stock.

Handling numbers were very impressive, as expected with such sticky rubber. Around the skidpad the IS 430 yanked our eyeballs out at .98g, which is light-years beyond the IS 300's .85g. More impressive was the IS 430's slalom speed. It navigated the cones at a frightening 75.3 mph--the second highest number we've ever recorded and 7.6 mph quicker than the IS 300.

It also stopped well with massive Brembo rotors and calipers at all four corners. Sixty to zero came in 104 feet, 11 feet better than the very respectable distance laid down by the IS 300 (115 ft.).

Instrumented numbers are only a small measure of a very big picture when it comes to evaluating a car, which is why driving it back to back on the track with its stock counterpart was educational. It's no secret the IS 300 isn't the fastest sedan in the world. But it is a well-mannered, textbook-handling car when it comes to front-engine, rear-drive machinery. All the standard formulas apply here--more throttle, more oversteer. These characteristics make it obvious when fundamentals are altered in a car's handling, like in the case of the IS 430.

Make no mistake about it, the IS 430 is quick around a track. But "quick" and "confidence inspiring" are very different things. We found the IS 430's steering to be weird. It produced uninspiring turn-in and mid-corner feedback, perhaps a product of the modified scrub-radius from the wide SSR wheels. Dynamically it was also a bit shaky. Around Turn One at Streets, the IS 430 went into a frightening pitch/yaw dance. Any high-speed, high-load corner produced an ass oscillation that would make Shakira proud. This kept us from completely committing to any turn on the street or the track.

Still, it cranked out lap times 6.3 seconds quicker than the IS 300, which is a lifetime on a track this short. Even with the handling issues, power and cornering speed were a huge improvement over the standard IS 300, which translated to a big difference in lap time.

Building a car with this many factory parts isn't as straightforward as it might seem. Even with heavy use of Toyota's factory parts bin, Millen's crew had to produce many custom solutions to the various problems this scenario presented. The biggest of those, according to fabricator Adam Dupre at Rod Millen Specialty Vehicles, was the electronic interface between the GS 430 engine and IS 300 chassis. RMSV built a custom controller to mediate between the stock GS 430 engine controller and the rest of the IS 300 wiring. Of particular concern was the dash instrumentation, which had to be made to work with eight cylinders instead of six.

Other concerns were more physical. Making the 4.3-liter engine fit functionally in the IS 300 chassis wasn't easy. The first order of business was fabricating custom tubular stainless-steel headers to facilitate the exhaust exiting safely and efficiently. Dupre says there's probably a small performance gain from the headers but they were designed primarily to allow the engine to fit into the space available.

Bolting the 1UZ-FE to the six-speed Getrag from a Supra required more custom work. Millen's crew measured the back of the block and CAD-modeled an adaptor to bolt to the modified transmission bell housing. The clutch, rear end and limited-slip differential are all products of the late Supra turbo as well.

The fuel system modifications weren't as complex. The IS 430 retains the stock IS 300 tank, but uses the 430's pump and sender with several custom lines between the body and the engine.

In all, the IS 430 is an impressive product of factory, aftermarket and custom parts and know-how. Making any mongrel machine--factory-backed or not--isn't easy, and Millen has made clear efforts to make the IS 430 an awesome performer. And he has, for the most part, found success. Plus, it does awesome burnouts.

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Lexus Is 430