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Mazda RX-7 Series 1 (X605)

The legendary car that saved the magnificent rotary engine from death.

By Michael Knowling
Photos by Julian Edgar

Click on pics to view larger images

This article was first published in 1998.

Founded in 1920, the Toyo Kogyo (Mazda) company built its first vehicle - a 3-wheeled truck - in 1930. It wasn't until 1960 that conventional car production commenced with the diminutive 360 Coupe, followed in 1962 by the 600 and then later the 800 sedan. These vehicles were powered by conventional piston engines - as have been the vast majority of Mazda models since produced.

But most relevant to this story was the 1967 announcement of the Mazda R-100 - a small elegant Wankel rotary-powered coupe that was an instant hit. Sure, the first rotary powered Mazda - the Cosmo - had preceded the R100, but that had been a mere toe in the water effort while the R100 was a complete package. Another rotary-engined car (the RX-2) appeared in 1970. It was claimed to provide an ideal mix of high-performance, luxury, safety and economy.

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1972 saw the release of the larger RX-3 that came fitted with either the 10A or 12A rotary engines, but the later models were marred by REAPS (Rotary Engine Anti Pollution System) which hurt torque. Nevertheless, Mazda predicted that by 1980, rotary engines would power 85% of all cars made in the US. A big call indeed! In late 1972, the RX-4 (Luce) was released. This car was also affected by REAPS and had more body weight to haul around. The beginning of the oil crisis in late-1973 saw Mazda pull back from their plans for big 15A and 21B engines, deciding instead to release only the 13B engine, which made an appearance in Japan in late 1973.

In 1974 the OPEC oil crisis meant sales of the relatively thirsty rotary vehicles took a dive, causing Mazda to axe some of its rotary-based concept car development. But the innovative Japanese company still believed in the superiority of the spinner engine, releasing in 1975 the Roadpacer AP and RX-5 (Cosmo). The larger RX-5 was very much a personal coupe aimed at the American market. Strangely enough, the RX-5 sold spectacularly in Japan but was received without much enthusiasm anywhere else in the world.

So far the story of Mazda's involvement with the rotary engine had been one of quite limited success. While in racing the engines had done very well, the Achilles heels of relatively high fuel consumption and poor emissions had meant that commercial success had eluded Mazda. Recognising the difficulties in convincing the motoring public to move away from the piston engine, Mazda had covered its bets by releasing both piston and rotary engined versions of the same cars. But the buying public simply wasn't switching allegiance as Mazda wanted. NSU had seen bitter defeat with the rotary-engined Ro80, and now it looked as if Mazda was heading down the same path - even with a rotary design far superior to that sold by NSU.

Then in 1979 the RX-7 was introduced. It literally saved Mazda's rotary engine program.

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Here in Australia, the first shipment of 150 RX7s sold out in weeks. In the US, Mazda put a ceiling on supply until its outlet chain could satisfy the huge demand. Even with this supply shortage, almost 29,000 RX-7s were sold in only 8 months...

The X605 RX7 (retrospectively dubbed the Series 1) came equipped with a twin-rotor 12A rotary powerplant which spun out 77kW at 6000 rpm. Torque was rated at 147Nm at 4000rpm. A vacuum secondary four-barrel Nikki carb was used for induction (EFI wasn't available on the engine until 1983) while it had a compression ratio of 9.4:1. There wasn't heaps of torque below 3000rpm, but the engine had a terrific willingness to rev to its 7000 redline. In straight-line performance, the RX7 could manage quarter mile passes in around 17.0-17.4 seconds and crack 60mph (97km/h) in 9.2-10.3 seconds. In terms of fuel consumption, last minute development to improve efficiency had paid off - the car averaged approximately 20mpg (13.5L/100km).

The engine was quite docile but around town could become slightly jerky if the driver wasn't in the mood to take charge. On the open road though, it was unrivalled for its lack of noise and vibration. A 5-speed manual gearbox came as standard, with 5th being over-driven at 0.825:1. The much rarer 3-speed auto of the car shown here was an optional extra.

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The RX7 was also the first rotary-engined Mazda road car that had real attention paid to aerodynamics. A claimed Cd of 0.36 was pretty good back in '79, coming from the use of pop-up lamps, low profile and gentle curves. Because of this, a top speed of around 180km/h could be reached - although 200 was claimed.

Being physically very compact, the rotor-motor could be mounted just aft of the front axle line to create the 51/49 front/rear weight distribution (overall weight was 2354lb or 1070kg). The 'Seven sported MacPherson strut front suspension with a tension rod and a sway bar. Rearwards there was a live axle, coil springs, Watts linkage, four-link layout, and a sway bar. Little 13x5 alloy rims wore the standard 185/70series Bridgestones to give quite slippery but predictable adhesion.

The sporty Maz handled very well indeed, showing traces of turn-in understeer, which gently progressed into mild oversteer if the driver was adamant on keeping the power applied. But as road testers agreed, "The secret to the driver appeal of the RX-7 is its rotary engine..." Braking was left to a combination of vented discs at the front and rear drums, a set-up which perhaps let the car down given its technology in other areas. Fade could easily be induced but initial stopping distances were quite good.

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The car's steering system retained a re-circulating ball design that provided 3.7 turns from lock-to-lock, but was criticised for what was then "the typical Japanese steering vagueness". The interior received a thick-rimmed leather steering wheel and cloth/vinyl seats that offered excellent lumbar support. The front backrests were also quite thin, allowing for improved rear leg and knee room. The driver was faced with well-sorted instruments which included a tacho, volt meter, fuel and temperature gauges and of course a speedometer.

With a A$14,850 admission price, the RX-7 competed in Australia against the Datsun 280Z, Alfa GTV and the Porsche 924. It won these comparisons largely because of its aggressive pricing and the flexible engine that was quite awe inspiring at a time when emission regulations were destroying 'classic' engine designs.

That stylish body, competent chassis and wonderful rotary engine combined to make a very popular (and now collectable) vehicle, one that saved the rotary engine from extinction. We have it to thank for paving the way to the current twin-turbo - we just hope the latter isn't the last RX-7....

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