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The Sole SPII

The SPII is the fastest factory-backed Mazda RX-7 ever produced. But there's only one of 'em...

Words by Michael Knowling, Pix by Julian Edgar

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Are you a fan of rotaries? Like to drive something that nobody else has? Well check out this white beauty owned by Marcus 'X' of Sydney - the only Mazda RX-7 SPII on the face of Earth!

The SPII is one of those vehicles with a real story behind it.

As you may be aware, the first generation RX-7 SP (which was based on the Series 6) debuted on the Australian market in 1995. Developed and assembled locally by Mazda Motorsport, the SP was a purpose-built production racer that went on to win a string of Bathurst 12-hour races and various other high-profile events. This was the car that caused much stress amongst the Porsche campaigners down pit lane.

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So what made the original SP such a formidable force in competition? Well the sequential twin-turbocharged 13B rotary copped an improved exhaust system, air intake and boost enhancements that brought power up to the tune of 204kW. Other features included a rear wing, bigger 17-inch wheels, a humungous 120-litre carbon fibre fuel tank and Kevlar race-type seats. These exotic materials contributed to a near 100kg weight saving over the normal Series 6 RX-7.

There were also some effective engineering changes, such as separate ducting to the airbox and intercooler. It is said that the normal Series 6 RX-7 suffered reverse flow through its intercooler at times of high engine load - heated engine bay air was drawn outward through the core.

With the change to the Series 7 RX-7, Mazda Motorsport looked at developing the SP theme even further. This was to become the SPII. But how do you improve on the already brilliant SP? Well, when you're obviously on the right track, it makes sense to simply continue further in that direction...

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The SPII's flywheel power output is difficult to pin down but Marcus has had his machine on a Dyno Dynamics chassis dyno where it recorded a highly impressive 240kW at the wheels. This is a long way from other claims of 220kW at the flywheel...

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Marcus tells us the original road-going versions of the SP were equipped with HT-10 turbochargers, while the race examples were fitted with larger HT-12 units. The SPII is fitted with the same HT-12s, which run anywhere up to 15 psi of boost, depending on conditions. It's just as well a large intercooler is installed! The exhaust system was also opened out with 3-inch stainless pipework; still, the factory rear muffler is responsible for keeping noise levels legal and, not surprisingly, causes some restriction. The air intake was also further improved with a Kevlar/carbon airbox and carbon pipes into the compressors. A pair of custom-made blow-off valves vent to atmosphere, as does the engine's air pump.

The SP and SPII also received a shorter 4.3:1 LSD to help keep the rotary in its optimal torque band - Marcus says the SPII really starts pulling away from the average RX-7 at anything more than about 4000 rpm.

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The SPII's use of exotic material reaches further than the original SP. The SPII employs a carbon fibre/kevlar nose-cone and bonnet. These parts not only save weight but their revised design also aids cooling. Like the original SP, there's a separate passage into the intercooler and airbox in order to maximise the efficiency of the intercooler.

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The carbon fibre/Kevlar bonnet incorporates two cooling vents near the base of the windscreen and another air outlet further forward behind the position of the intercooler. This outlet was apparently fitted with a removable blanking panel in order to meet ADRs - the plate is best removed for motorsport use.

The only other body alteration on the SPII is the fitment of a towering rear wing. Interestingly, the standard Series 7 wing was merely shifted further rearward and elevated higher into the laminar airstream. No drag or downforce figures are available.

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Just like the original SP, the SPII used a 'plus one' wheel fitment. Standard, the SPII kicks along on 18 x 8 BBS alloys wearing 235/45 and 255/40 Yokohama A-008Ps. Marcus has since moved to a new set of Dunlop rubbers.

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Ride height of the SPII is slightly lower than conventional RX-7s thanks to revised rate Eibach springs working with Bilstein dampers. It is said that the SPII uses softer rear springs than standard, which aids traction and swings the handling balance more in the direction of oversteer. Whatever the case, these are truly phenomenal handing cars.

Brakes on the original SP were upgraded to 300mm ventilated front discs and 4-pot calipers. These were carried over to the SPII along with revised ABS calibration.

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Surprisingly, the race-type Recaros used in the original SP were dropped for the SPII. Instead, the original RX-7 pews - which offer a great combination of access, comfort and support - were retained for the job. The only interior mod was yellow highlights on the seats, doors and steering wheel. Keen rotary fans might pick that Marcus has swapped the factory oil pressure gauge for a boost gauge from a Series 8 RX-7.

So there you have it. The SPII gave tremendous power, an exotic body upgrade, bigger rims'n'rubber, upgrade suspension and brakes and a distinguished interior trim. Things were looking very rosy during its development and the car progressed to the point where it appeared as a concept at the 1998 Sydney International Motor Show.

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However, just weeks later it was announced that Mazda Australia would no longer be importing the RX-7 and so there was no point continuing with the SPII program. The vehicle that you see here is the one and only development prototype - a labour of love for the Mazdasport team. Following this sad chain of events, the car was snapped up by a very enthusiastic Marcus. Marcus has sheltered and loved this machine to death, but rest assured it doesn't hang around gathering dust - Marcus has racked up more than 65,000 kilometres in addition to the 12,000 kilometres that were on the car when it came into his hands.

So, apart from going down in the Mazda rotary hall of fame, where does the one-off SPII go from here?

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Well, that's up to you - yes, you! Marcus is currently considering offering the SPII for sale at AUD$150,000. This is, remember, a one-of-a-kind vehicle that's the fastest of the breed - a true collector's machine.

Interested parties should in the first instance send an email to michael@autospeed.com.

Thanks:

David Morris (DMRH) 0408 426 944

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