This thread was created by Terry Saunders to nail down the major differences between the VVTi and non-VVTi incarnations of the 2JZ-GTE. It expanded into quite a large discussion over the way VVTi works on the Supra, ending with a revelation that, once again, Toyota were well ahead of the game because it's an infinitely variable system - about 10 years before anyone else hit the mainstream with such a setup
Thought this may be useful. Please feel free to add to it:
ECU. The VVTi has 2 x 16 bit whilst the stock JDM is 2 x 8 bit. The ecu is obviously much faster. It is based upon the later Lexus units and is very powerful.
Fly-By-Wire. In conjunction with the ECU the FBY system will close the throttle if it senses detonation, high coolant temps, etc
The VVTi system. Adjusts the intake cam timing. This gives significantly more low end torque, and helps the larger turbo'd car spool earlier.
Rev Limit. The rev limit on a stock VVTi is 7200 rpm whilst the Stock JDM is 6800 rpm.
MAF. The VVTi uses MAF, The MAF is far more accurate than a speed density system. The downside is that the MAF will eventually become a restriction if big power is required.
Inlet. The VVTi uses a smaller inlet manifold. This will improve torque, but may become a retriction on really big power cars ( 650+ bhp)
Wasted Spark ignition. This IMO is a step backwards to coil on plug.
Trac. The VVTi TRAC is too over-sensitive. Pulling the fuse will put the car into "snow" mode.
Engine Mounts. This applies to all Facelift cars. TMC changed the engine mounts for some strange reason. These are prone to failure and are not as "beefy" as those on earlier cars.