A Unique Engine and Iconic Car
By Shanuka Kadupitiyage Ceylon Today Features
When you think about parts of an engine, you would immediately think about pistons, camshafts and timing belts among others. These are all parts that make a traditional combustion engine that we use every day. Could you imagine a fully functioning engine that could do all of this and more, without any of these parts?
Wankel rotary engine
We’re talking about the Wankel rotary engine of course. The engine was developed by a German mechanical engineer named Felix Wankel. He patented the designs of his engine and soon went to develop it, until Mazda took an interest in his design.
Wankel’s engine was unlike anything that has ever been seen before, using a triangular rotor to replace most of the traditional parts of an engine. It doesn’t even look or sound like a normal engine to begin with.
In a traditional combustion engine, the air-fuel mix flows into the combustion chambers, where they are compressed using a piston before ignition, where the piston is forced down. This up-and-down motion caused by the pistons is converted into a circular motion using a crankshaft, connected to connecting rods. While the system is effective, there are a few drawbacks to this design.
The biggest issue is that there are lot of moving parts which are delicate and are likely to fail at high revolutions. It also means that the size of an engine is pretty large, with a lower weight to power ratio. Because of the conversion of vertical movement into rotational movement, there is also the loss of power during that transition.
A Wankel engine avoids all these issues by providing a completely new design.
How it works
The triangular rotor inside Wankel’s engine spins inside the engine’s chamber. The air-fuel mix enters the chamber and is sealed and a tiny air pocket is formed from the two apexes of the rotor. As it spins along the wall, the mix is compressed because of the engine chamber’s shape. Here, two spark plugs ignite the fuel and cause an explosion, forcing the rotor to move and once the air pocket reaches the exhaust, it is released into the atmosphere as the rotor keeps spinning, ready to repeat the cycle.
Because the engine operates in a rotational motion from the get-go, there is no need for complicated parts that can fail. Since there are so little moving parts, there is less friction and movement, meaning Wankel’s engine has a better weight to power ratio and is able to provide more power with a smaller engine size. It also made repairs a lot easier and could operate at very high revolutions that an ordinary engine cannot handle; in fact these engines were built to operate in such conditions.
Mazda steps in
In the early 1960s, Mazda was in need of a little spice to make a statement in the automotive market. The President at the time of Mazda, Tsuneji Matsuda was interested in developing unique technology to make the company stand out from the competition. His attention quickly turned to Wankel’s engine thanks to its unique design, simple structure, compact size and high power.
Unfortunately, the rotary engine at that time had some major issues, the biggest one being the walls of the engine taking on some serious wear and tear because of the apexes of the rotor scratching against them. Mazda’s team of engineers led by Kenichi Yamamoto soon cracked the case and found solutions to many of their problems, even addressing the issue on the apexes using carbon-aluminium apex seals.
Mazda rotaries steal the show
After finally developing an engine that can be mass produced, reliable, practical and drivable, Mazda didn’t wait long to release its first car powered by a rotary engine; the Cosmo Sport in 1967. Mazda’s Cosmo took the world by surprise. The company finally achieved what it set out to do with Matsuda at the helm, establishing the company as a global contender in the automotive industry with new technology.
Taking the time to redevelop the rotary engine, Mazda made some massive changes to their original rotary engine the years after and premiered a brand new rotary powered sports car; the now legendary RX-7.
The Mazda RX-7 was one of the most unique sports cars to ever hit the market. It had a light body and easily serviceable parts. Because the rotary engine is smaller than any traditional engine, it could fit closer to the middle of the body, bringing an almost perfect weight balance to the car. With a lightweight, balanced body and rotary engine, the RX-7 became a favourite among enthusiasts as well as a headliner in motorsport, winning championships such as the 1980 and 1981 British Touring Car Championship and completely stealing the show in the American IMSA competition, dominating the races for 12 years, scraping an unmatched 100 wins during that period.
Mazda’s RX-7 also made its way into the headlines in endurance races, winning the 1981 Spa 24 Hours in Belgium and the 24 hour Le Mans, the first Japanese automobile and carmaker to win those events respectively.
Evolution in design
Mazda didn’t stop developing the star-boy in it’s rotary line-up outside of the track either. During these years, the company made significant upgrades to the RX-7’s design and technology, which resulted in the second-generation RX-7 (known as the FC) being available for the public. Buyers had the option of owning a turbocharged FC RX-7 which provided nearly double the horsepower of the first generation and was an instant hit.
However, the RX-7 truly became an iconic vehicle with its third generation, also known as the FD in 1991. With the first and second generations, Mazda took inspiration from European automobiles for their designs. However, they came up with a completely unique design with the FD RX-7. It disregarded the ‘boxy’ aesthetic and chose a more smooth, seamless appearance that is still good enough to turn heads when driving down the road.
Good looks wasn’t the only thing the FD had. It had the now famous 13B rotary engine paired with a sequential twin-turbocharger system. The first turbo would operate at low engine rpm’s and the second, larger turbo unit would take over in higher ranges. This complicated system was developed by Mazda with Hitachi and was the first ever Japanese car to be exported overseas with such a mechanism.
A massive fan following
There was much to love about Mazda’s rotary monster. The perfect weight balance continued in their generations which made it nimble when taking corners. All three generations had great style (although the FD was the showstopper) and you can’t ignore that unique rotary engine that put power to the wheels.
Traditional engines rarely were able to go over 7000 rpm, yet the RX-7 easily ran at 10,000 rpm and higher. Mazda actually recommended owners to drive their rotary RX-7 engines this way to keep them running smoothly, which driving enthusiasts were happy to oblige with.
If Mazda’s rotary cars were so good, you might wonder why everyone else didn’t adopt the technology or why you don’t see rotary powered cars today.
While there were companies that attempted making rotary powered vehicles they were soon dropped because although rotary engines were unique and fun to drive, they were hard to repair.
The apex seals were especially prone to failure and Rotary engines were notoriously bad at fuel economy and emissions.Mazda tried to fix that with the RX-8 after Ford bought a majority share of the company. Yet it was a pale comparison to what the RX-7 was.
With a changing world that is moving towards more efficient machines, it might take a while to see another rotary engine make its home in a new sports car.
While Mazda is looking for new ways to implement the technology, all we can do is look back and enjoy the journey Mazda took with its rotary powerhouse.