Why Mazda’s Rotary Automobile Engine Never Became Widely Popular

Why Mazda’s Rotary Automobile Engine Never Became Widely Popular

With four wheel drive, four wheel disc brakes, a semi automatic shift-operated by pressing down on the gear knob to operate the clutch, minimal rear overhang and gentle swooping bodywork, its clean lines look quite contemporary for the early 80s, yet this was launched in 1967. It deservedly won car of the year. It handled and rode superbly. The rotary engine was so smooth and quiet running that a warning buzzer had to fitted to alert the driver that it was approaching its 9000rpm redline. True, it was thirsty at fifteen miles per gallon and it wasn’t that fast at 108 mph and 0–60 in around fifteen seconds, but as a complete package there was nothing to touch it.

Sadly, it was too good to be true. NSU’s ultimate fate was certainly a cautionary tale for other car firms dabbling with the rotary. Despite the development, NSU really hadn’t come to grips with effective apex seals for the rotor tips and these early wankels were junk in as little as 20–30,000 miles. On a car that was priced on a level with a Jaguar XJ6 in 1968, this was unforgivable. An urban legend tells of Ro80 drivers, when passing one another, holding up fingers to indicate the number of replacement engines they’d been through. You see, NSU honoured warranty claims until they bled white. When they ran out of funds, the firm was bought out by VW, the Ro80 soldiering on in limited numbers until ‘77, while VW launched the NSU designed (conventional engined) K70 as an unsuccessful Golf predecessor.

GM also took out a license on the wankel. If this new motor was going to be the way forward, they wanted a part of it.

With that in mind, AMC who were designing their own great white hope in the form of the Pacer, made a deal for GM to supply them with engines.

See that ugly pig snout? Looks wrong, doesn’t it? That’s because the Pacer was originally designed for Rotary power, hence the low bonnet line. When it became clear that the rotary was a hopeless case for anything other than niche market oddities-after NSU had gone bust and at the time of the Arab oil embargo-suddenly a 15 mpg engine didn’t look so appealing-GM made it clear they had lost interest and no engines would be forthcoming. AMC simply stuffed in the only engine they had that would fit, the ageing 4.2 straight six, set well back in the bulkhead, to get the Pacer launched, then soon after offered a V8 option that required the less than subtle nose surgery pictured above.

Quite simply, the rotary was an interesting technological cul de sac, but eminently unsuitable for mass market cars particularly once gas started getting expensive. It took Mazda years of development to get the rotary working reliably, and even then it would be a brave soul indeed who would purchase a used RX7 with more than 70k on the clock that was still on its original engine. Those rotor tip seals still aren’t as durable as the piston rings on a conventional engine and remain the designs weak point. The fundamental design flaw of having a moving combustion chamber as on a rotary also means that part of each fuel charge is still burning when it gets fired down the exhaust, meaning wasted energy, increased fuel consumption and dirty emissions, not helped by the necessary total loss lubrication system which means oil gets burnt along with the fuel. On the other hand, if all you want to do is go racing, then a turbocharged rotary fits the bill perfectly. It revs its butt off, produces great buckets of bhp and fuel economy, longevity and emissions are irrelevant.