27 Oct 2012

Mazda - Why the Wankel must not return

This is an article by American writer, Max Prince, who is currently living in the UK and studying for his masters degree in auto journalism at Coventry University. It deals with the possibility of Mazda resurrecting the rotary motor, as reported at the Australian International Motor Show in Sydney yesterday.

An Entreaty To The Winged M
Mazda RX-7
Last night, I read an article on the New Zealand Herald website in which Mazda CEO Takashi Yamanouchi asserted his desire to integrate a rotary motor into future models.

I was absolutely horrified, and I want to explain why.

In my lifetime, I have never had the misfortune of witnessing a grown man reduced to tears over an automobile, but I can recall one specific instance where I honestly believed it was going to happen.

It was during autumn some years ago, deep into the morning hours, sitting in an overwhelmingly silent garage. My roommate Ted and I had spent the better part of two days and nights covered in grease, slaving away on The World’s Most Infuriating Car. After swapping two different engines in the past year, each of which had grenaded in dramatic fashion, we couldn’t get the third one to start. No matter what we did, being able to enjoy a spirited drive the next day was out of the picture. Moreover, it was quickly becoming clear that the premise of ever driving this vehicle was simply an illusion, one too good to be true. Ted slumped over. With a hollow, defeated thud, he let his forehead drop onto the steering wheel.

If you haven’t already drank a litre of drain cleaner as a result of that utterly joyless premise, you may be wondering what The Worst Car In The World is, and what engine could be capable of such torment.

It is the Mazda RX-7, powered by a 13B rotary.

To begin with, let me familiarize you a little more with the modern automotive rotary engine. It's the brainchild of Dr. Felix Wankel circa 1954, presumably with input from Lucifer and/or a band of drunken sadomasochists. Wankel’s creation is a pistonless monstrosity where triangular engine internals spin on a shaft, thus eliminating the lost energy of a reciprocating cylindrical motor. In the most basic terms, imagine spinning a stale doughnut on a pencil – with very little effort it will rotate very quickly. The hypothetical benefit of this design is far less parts, and therefore less weight. But how could Felix create internal combustion with this new idea? His answer was to fit the triangular engine internals (rotors) into a circular enclosure to create three chambers.

And that’s it. That’s the problem, right there. The entire concept of this motor is based around the notion of fitting a triangle into a circle. After trying to make this work for hours myself, I gave up and never tried again. The difference is that I was four years old and playing with colored plastic blocks, not a mechanical engineer with a doctorate from Technische Universit√§t M√ľnchen.

What resulted from this geometrical abomination, as Ted and I learned through endless hours wrenching, was the least user-friendly piece of mechanics ever put into mass production.
A rotary engine

The issues were innumerable. To begin with, it turns out that no known material can actually seal a rotary triangle/square chamber, so they tend to lose compression anywhere from 5,000 to 150,000 miles. Who knows? It could happen at any time. To lubricate the seals that break anyway, this motor has a system that extracts oil to mix with the fuel before being injected. In addition to the purchase of an extra pint every 1,000 miles, this nifty feature assures a semi-constant odor of burning oil. At one point, Mazda had to recall every rotary motor (yes, every one) because of oiling problems.

Oh, and nobody really cared about fuel consumption in 1957, including Dr. Wankel. Unfortunately for us living in this century, getting 15-20 miles to the gallon (which most rotary cars will do in real world application) is more expensive than a moderate cocaine habit. It will even drink plenty of fuel simply idling, which is continually required, because cold driving (or shutting down before operating temperature) will flood the engine and lock it.

To be fair, in the right conditions, the motor will produce some impressive horsepower figures and is able to rev higher than most piston engines. But will you be able to feel it? No. Because of the engine design, rotaries produce torque in the same quantity as Honda four-cylinders. And, as an added compliment, some models (like the Mazda Ted owned) come with a complex turbocharger system rather than a bottle of scotch and a handgun, which is what rotary owners really need.

The average car buyer does not know any of this, and will eventually destroy the motor through improper use. The enthusiast car buyer knows all of this, and will eventually destroy the motor through normal use. Either way, you can inevitably find both of them riding a bicycle to work on Monday mornings.

But for some reason, as with any automotive niche, there is a strange group of people who love these motors. These people are like some strange cult, insistent on drinking the rotary Kool-Aid no matter what it does to them.

I can somewhat relate to similar cases of devotion, like the British roadster fanatics or classic Alfa fans – at least those cars are enjoyable for the three weeks of every year they actually run properly. But a fuel-guzzling, oil burning, torqueless money pit that sounds like a gardening tool? No thanks.

Eventually, Ted decided to get a different RX-7, this one with a racing engine assembled by one of America's best rotary builders. We traveled 596 miles to collect the car, which lost compression the following morning during our return trip and died 100 miles from his house. After that, Ted swore them off. He realized, as Mazda did around this time last year, that the premise of a super-efficient, lightweight, high-revving engine is marvelous – who can disagree? But we’ve now seen numerous iterations of the automotive rotary for half a century, and it just isn’t translating.

Please Mazda, stop making rotary-powered cars, for all of our benefit. It's over.

Communism works in theory, too. Maybe we can let that one go next year.