From wikipedia:
The 1JZ-GTE employs twin CT12A turbochargers arranged in parallel and blowing through a side-mounted air-to-air intercooler. With an 8.5:1 static compression ratio, the factory quoted power and torque outputs are 206kW (280 HP) at 6200 rpm and 363Nm at 4800 rpm respectively. These early 1JZ-GTEs are most commonly available with an auto transmission but a 5-speed manual version was available in the Supra 2.5 GT. Yamaha is believed to have had a hand in the development or production of these motors (possibly the head design), hence the Yamaha badging on certain parts of the motor, such as the cam gear cover and possibly the cylinders themselves.
In the following year (1991), the 1JZ-GTE was slotted into the all-new Soarer GT. Output remained at 206kW/363Nm and, again, most examples come tied to an auto trans. These 1JZ-GTE powered Soarers are quite common on the Australian market (as ‘grey’ imports).
The early generation 1JZ-GTEs are a great engine from a bang for buck point of view, combining the inherent smoothness of an inline 6 cylinder engine with the revving capacity of its short stroke and early power delivery of its small, ceramic wheeled turbochargers. The ceramic turbine wheels are prone to delamination in the setting of high impeller rpm and local temperature conditions, usually a result of higher boost. IMPORTANT: On that note, the 1st Gen 1JZ's were even more prone to turbo failure due to there being a faulty one-way valve on the head, specifically on the intake cam cover causing blow-by to go into the intake manifold. Also on the exhaust side a decent amount of oil vapor flows into the turbos causing premature wear on the seals. The later 1st Gens had this problem fixed and in Japan there was actually a recall in order to repair the 1st Gens, though that does not apply to 1JZ's imported to other countries. The fix is simple, and involves replacement of the PCV valve (2jz); all parts are available through Toyota.yo
The "3rd Generation" of 1JZs were introduced around 1996, still as a 2.5 turbo, but with reworked head incorporating Toyota's newly developed continuously variable valve timing mechanism (VVT-i) , modified water jackets for improved cylinder cooling and newly developed shims with a titanium nitride coating for reduced cam friction [2] . The turbo setup changed from parallel twin turbo (CT12x2) to a single turbo (CT 15B). The adoption ot VVT-i and the improved cylinder cooling allowed the compression ratio to be increased from 8.5:1 to 9.0:1. Even though the OFFICAL power figures remained the same on paper (280HP @ 6200RPM) the Torque was increased with 20NM to 379NM at only 2400rpm (Originally 363Nm at 4800rpm). Combined Engine improvements resulted in improvements in engine efficiency that led to the fuel consumption reduction of 10%. Overall the adoption of a much higher efficiency single turbocharger than the twins, different manifold and exhaust ports were responsible for most of the 50% torque increase at low engine speeds . This engine was used primarily in Toyota's X chassis cars (Chaser, Mark II, Cresta, Verossa), the Crown Athlete V (JZS170) and in the later JZZ30 Soarer, as the JZA70 Supra was long discontinued by this time.
Peak torque was shifted to 2400rpms with the latest generation 1jz...
