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This article was first published in 2003.
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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.
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The Mazda RX-7 in Australia
In late 1998, Mazda Australia announced it would no longer be importing the
RX-7. The decision came as no shock. From 1996 to 1998 only 30-40 RX-7s were sold per year - not enough for a big company to bother about.
There was a last-minute rush to pick up the last few examples, but the RX-7 saga
fizzled out rather uneventfully.
Only now - in 2003 - has the rotary engine reappeared on the Australian
market with the debut of the RX-8.
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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.
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RX-7 Chassis Code Nomenclature
In case you were wondering, FD RX-7s are identifiable by a system other than Series 6, Series 7 etc. The 1991 - 1995 Series 6 RX-7 carries a FD3S-1/2/3000 chassis code and the 1996 - 1998 Series 7 is officially known as the FD3S-4000. The 1999 - 2002 Series 8 RX-7 is coded FD3S-5/6000.
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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...
Contact/Thankyou
David Morris (DHRH)
0408 426 944
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