You've got to hand it to Mazda. Ever since it released the 'Series 1' RX-7 in the late '70s, it resisted all temptation to soften its affordable sportscar design - the brilliant weight distribution, the wonderfully linear torque delivery and driver emphasis have long remained RX-7 trademarks. Contrast this with Nissan, which really lost the plot with its Zed during much of the 1980s.
The RX-7 saga came to a sad end in August 2002 with the axing of the so-called Series 8. The Series 8 RX-7 was unleashed on the Japanese market in January 1999 and the up-spec Type R and RS versions gained recognition for having more power than any other prior RX-7. Note that the Series 8 RX-7 was never officially released in any country outside of Japan.
As you may be aware, car manufacturers in Japan have a loose agreement with the local government to produce vehicles of no more than 280ps (206kW). Although there are a few vehicles that have crept past this limit, we're told that the top-line versions of the Series 8 Type R and RS models are dead-on the 280ps ceiling. The only mass-produced rotary engine that exceeds the 280ps limit is the triple-rotor twin-turbo 20B Cosmo (which is reputedly good for around 300ps or 221kW).
Okay, so the Series 8 RX-7 might not go down in history as the most powerful production rotary - but it is certainly the fastest.
Weighing in at 1260 kilograms in go-fast RS form, you're looking at a power to weight ratio of 6.1 kilograms per kilowatt. That whips the new Nissan 350Z (at 7.0 kilograms per kilowatt), so it's no surprise that 5-second 0 - 100 km/h performance is easily within reach. The Japanese motoring press raved over the top-line Type RS's on-road and on-track performance.
The availability of the 280ps engine in the Series 8 Type R and RS was certainly the biggest progression over the Series 7.
So what changes gave the Type R and RS a 15ps (11kW) increase over Series 7 twin-turbos, you ask? Well, the 9.0:1 static compression twin-rotor 13B remains largely unchanged, but its small HT-12 sequential turbochargers received smaller turbine housings and altered blade profiles. At the production stage, each turbine housing was also coated with an adbradable resin and the turbine wheel was then spun in order to shear way the excess resin. Once hardened, this dramatically increased the turbo efficiency. The 280ps motor also ran slightly increased boost pressure (11 psi) and slightly less exhaust backpressure. Exhaust flow was enhanced by using a thinner wall exhaust tube (to increase the internal flow area) and less restrictive mufflers. Even so, the factory exhaust has just a 1¾-inch ID, meaning massive power increases can be found with aftermarket exhaust systems.
With these changes, the Series 8 Type R and RS are credited with the full 280ps (206kW) output at 6500 rpm along with 310Nm at 5000 rpm. And if you reckon this is a peaky engine, guess again - more than 280Nm of torque is available from as low as 3000 rpm, making the car extremely flexible.
The Type R and RS's increase in power also called for some added reliability measures. The existing oil injectors for each rotor - which are mounted in each housing near the intake port - were modified to provide quicker response to accelerator inputs. The radiator was also upgraded to a triple-core unit and an external cooler added. Note that the Series 8's revised nosecone is also responsible for dramatically improved cooling efficiency over the Series 7.
Interestingly, the Series 7 was susceptible to poor oil cooling and intercooling when pushed hard on the street or when raced. We're told that cooling airflow available to the intercooler was impaired whenever the engine was at full power and sucking a vast quantity of induction air from a shared forward-facing intake. Mazda Australia's testing for the SP program apparently revealed reverse cooling flow through the intercooler core! This problem was solved in the Series 8 by separating the incoming airflow to the intercooler and airbox - a 'letterbox' slot in the front numberplate mount now feeds induction air to the airbox. Thanks to this mod, a whopping 80 percent improvement in intercooler cooling airflow was seen.
The pipe from the turbochargers to the intercooler is also known to pop off at high boost pressure in the Series 7 RX-7, so the Series 8 Type R and RS use a one-piece alloy pipe that's firmly bolted into place. As far as we can determine, this part is exclusive to the Type R and RS.
A 5-speed manual is typical for the Series 8 RX-7 but lazy buyers had the option of a 4-speed automatic transmission. Note that a 4-speed auto was available in Japan throughout the FD's life, but never in Australia. More interestingly, however, is that a MazdaSpeed proven 4.3:1 LSD (instead of a 4.1:1 LSD) came standard on the top-line Series 8 Type RS. This is the same diff as fitted to the Series 6 SP. Appropriate high speed cruising rpm is maintained in the Type RS thanks to a taller 5th gear ratio.
The FD-series RX-7 was built on a wishbone suspension arrangement that was widely praised as communicative and controllable. The Series 8 RX-7 has virtually the same suspension hardware as the Series 7, but the RS version scores Bilstein dampers along with 17 x 8.5-inch factory alloys wearing 235/45 and 255/40 Bridgestone Potenzas.
The standard Series 8 RX-7 carries over the 300mm ventilated front discs and ABS, while the Type R and RS use the 330mm discs that were proven on the Series 6 SP. These big discs required relocating the 4-pot calipers and recalibrating the ABS system.
At this point we should mention the Mazda produced a few different versions of the Series 8 RX-7. First is the base Type RB version, which makes 255ps (187kW) in auto form and 265ps (195kW) in 5-speed manual form. Next is the Type R that offers 280ps and the aforementioned Type RS, which adds Bilsteins, a shorter diff, 17s and a few body and trim differences.
As mentioned, the Series 8 RX-7 boasts a much more efficient nosecone design - and there's not much else to distinguish it from the Series 7. The round taillights were carried over from the Japanese spec version but the MazdaSpeed inspired adjustable rear wing is new. The only other body mods include front driving lights and backlit rear safety lights.
Inside, the Series 8 is pretty similar to the Series 7. The troublesome oil pressure gauge makes way for a turbo boost gauge, a Nardi unit replaces the much-criticised oversized steering wheel and twin airbags come standard. Options include remote central locking and a Bose sound system. Leather trim and a power sunroof were available as special order items.
A decent number of Series 8 RX-7s were sold in Japan over the car's 4 year lifespan - 15,000 units to be exact. A Spirit R limited edition was also introduced near the end of the model run. The RX-7 was strategically priced in the Japanese market (equivalent to AUD$55,000) but it's obvious that it would've struggled in Australian market after the expensive importing and ADRing costs were tacked on. As such, the only Series 8 RX-7s you'll see on Australian roads are private imports like David Morris's 2000 Type RS seen here. This particular vehicle has just been sold, but at the time of writing, David has another red Type RS with 17,000 kilometres on the clock that he's offering for AUD$63,000.
We enjoyed a brief test drive of the black RS and can vouch that it's a brilliantly responsive and torquey performer with eye-widening top-end performance. The steering is razor sharp, the suspension taught and very well controlled and the brakes ample. The Series 8 is certainly a worthy final act...
David Morris (DHRH)