It’s a Shame Lexus Didn’t Put the V8 Manual IS 430 Into Production
This 2003 SEMA concept had all the right ingredients to be a legendary sport sedan.
Back in 2003, car culture was a different place. The internet didn’t rule all our lives; forums were only just finding some traction. Limp Bizkit was resonating from every rattling removable-faceplate head unit in Acura Integras nationwide, Need for Speed Underground was just released, and our fearless leader Andrew P. Collins was bumpin’ beats from the trunk of his FC RX-7. Life was good.
Life got even better too, because for the modding extravaganza show in Las Vegas, SEMA 2003, Lexus commissioned a 4.3-liter V8 IS 300 sedan, dubbed the IS 430. It may be the great lost Lexus of all time, and it wasn’t even that insane of a build, made using parts-bin Toyota stuff to create the best Lexus IS of them all.
18 years removed, the paint scheme is quite dated with strong Chip Foose vibes, though I don’t think he had any hand in the car. The vehicle was actually handled by Rod Millen, more specifically his special vehicles division. You may recognize the name from legendary Pikes Peak racing cars, and being a generally fast Kiwi driver. A fitting person to build a fast Lexus. He is also the brother of Steve and Rhys Millen, other names you’ve likely heard. The family makes a fast Kiwi trifecta.
The IS 430 was genuinely a parts-bin affair with some special magic from Rod Millen. The aforementioned 4.3-liter V8 was the 3UZ-FE VVT-i engine from the larger GS 430 sedan. Drivetrain components like the differential and axles were from the GS430 as well, all bolting easily. The trick is that the GS 430 and IS 300 share an incredibly similar platform, and things readily bolt-on from each other’s parts bins.
The V8 is quite cool on its own, but the pièce de résistance of the entire build is the six-speed manual transmission, also parts-bin. It is the Getrag V160 straight out of a Mark 4 Toyota Supra, legendarily stout and more than sufficient for the power. That is also a bolt-in affair, with mild clearancing. Luckily, stuff like the clutch pedal and miscellaneous hydraulics from the normal five-speed manual IS can be used.
A set of nice SSR wheels and a big brake kit finish the bolt-on treatments off. The slightly more complicated part was making the actual combination of 3UZ V8 and V160 manual to play nice with each other. Nowadays, the answers for that are everywhere, and parts to make it work are a google search away. Back in 2003, Rod Millen had to figure it out on his own.
My personal experience with the couple of VVT-i 1UZ engined cars that I’ve owned, it seems that it would be a huge feat of electronics to make it work without modern standalone ECUs running the show. Rod had to use factory ECUs, and trick the V8 into working with the manual, literally. Even with factory Toyota support, they weren’t going to spend time and money with a one-off car.
I’d imagine the primary sticking point with the VVT-i engine and transmission interfacing is the new-for-Toyota partially electronic throttle body. It’s very strange, and it is fully electronic, but still has a true cable running from the throttle pedal to the throttle body. What happens is that the throttle position sensor is directly on the throttle body, and it uses that signal to electronically move the throttle blade. It also has an internal clutch as a backup if the electric motor fails. Neat engineering, but somewhat pointless. The primary goals are to integrate a more advanced traction and stability control program.
The original A650E five-speed automatic that sits behind most 3UZ V8s has advanced transmission electronics that actively talk to the throttle body. This conversation is the part that Rod Millen somehow reconciled with his magic touch. The ECU will smooth out and cut some throttle to achieve smoother shifts, so your input to the throttle is almost never 1:1 with the throttle body.
I’m not sure exactly what methods by which Rod achieved this, but my guess is that he tricked the ECU into thinking the car’s in neutral. These cars didn’t have a neutral rev limiter like modern cars, but the ECU can throw a colossal fit if it doesn’t recognize the transmission in the right conditions. I’m sure the correct balance of unplugged sensors and fake signals got the car down the road.
All of this amounts to the ultimate Lexus IS. I can’t imagine how dope this car would be to drive, with the sweet-shifting V160, the torquey 3UZ, and the caramelized refinement of the IS chassis. It has zero weight penalty, save for the gearbox. In fact, the V8 weighs a few pounds less than an equivalent twin-turbo 2JZ, makes the same power stock-for-stock, and gets 10 more mpg highway.
This is the engine the IS always should’ve had. Maybe somebody out in the world has built something similar and can tell us what it’s really like to drive… or let us take a spin? Anybody?