Mazda RX7 FD3S Spirit R Explained!!
Channel: GTSDRAG
Date: 2019-01-07

The third generation RX-7, FD (chassis code FD3S for Japan and JM1FD for the North American VIN), featured an updated body design. The 13B-REW was the first-ever mass-produced sequential twin-turbocharger system to export from Japan, boosting power to 252 hp in 1993 and finally 276 hp by the time production ended in Japan in 2002.

In Japan, sales were affected by this series' non-compliance with Japanese dimension regulations and Japanese buyers paid annual taxes for the car's non-compliant width. As the RX-7 was now considered an upper-level luxury sportscar due to the increased width dimensions, Mazda also offered two smaller sporting cars, the Eunos Roadster, and the Eunos Presso hatchback.

The sequential twin turbocharged system, introduced on this series in 1992, was extremely complex and was developed with the aid of Hitachi and previously used on the exclusive-to-Japan Cosmo series (1990-1996 JC-series). The system used two turbochargers, one to provide boost at low RPM,10 psi  of boost from 1800 rpm. The second turbocharger activated in the upper half of the rpm range, during full throttle acceleration — at 4000 rpm to maintain 10 psi until redline. The changeover process occurred at 4500 rpm, with a momentary dip in pressure to 8 psi  and provided semi-linear acceleration and a wide torque curve the throughout the entire rev range under "normal operation".

Under performance driving the changeover process produced a significant increase in power and forced technical drivers to adjust their driving style to anticipate and mitigate any over-steer during cornering.The stock turbo control system used 4 control solenoids, 4 actuators, both a vacuum and pressure chamber, and several feet of preformed vacuum/pressure hoses, all of which were prone to failure in part due to complexity and the inherent high temperatures of the rotary engine.

Australia had a special high-performance version of the RX-7 in 1995, named the RX-7 SP. This model was developed to achieve homologation for racing in the Australian GT Production Car Series and the Eastern Creek 12 Hour production car race. An initial run of 25 originals were made, and later an extra 10 were built by Mazda due to demand.The RX-7 SP produced  274 hp and 357 N⋅m (263 lb⋅ft) of torque, compared to the 236 hp and 294 N⋅m (217 lb⋅ft) of the standard version. Other changes included a race-developed carbon fibre nose cone and rear spoiler, a carbon fibre 120 L fuel tank (as opposed to the 76 L tank in the standard car), a 4.3:1-ratio rear differential, 17-inch wheels, larger brake rotors and calipers. A "three times more efficient" intercooler, a new exhaust, and a modified ECU were also included. Weight was reduced significantly with the aid of further carbon fibre usage including lightweight vented bonnet and Recaro seats to reduce weight to 1218 kg (from 1250 kg). It was a serious road-going race car that matched their rival Porsche 911 RS CS for the final year Mazda officially entered.The formula paid off when the RX-7 SP won the 1995 Eastern Creek 12 Hour, giving Mazda the winning 12hr trophy for a fourth straight year.The winning car also gained a podium finish at the international tarmac rally Targa Tasmania months later. A later special version, the Bathurst R, was released in 2001 to commemorate this, in Japan only. It was based on the RX-7 Type R and 500 were built in total, featuring adjustable dampers, a carbon fibre shift knob, carbon fibre interior trim, special fog lamps and a different parking brake lever.