History Of The Rotary Engine and Mazda Rx-7

             Reading this blog post means your probably a fan of the rotary engine and Mazda Rx-7, Today it's hard to picture a world without the rotary engine. The Rotary engine came in one of the best cars to ever come out of japan Rx-7. The cult following the Rotary engine attracted throughout the years small but very hardcore fans. They are the ultimate gear heads from my point of view.

                  The rotary engine was a huge success despite that success when it's coming to reliability it wasn't good enough, When you finish reading this post you will know everything you need to know about the Rotary engine. What made rotary the engine of the future and why the engine died off.

Felix Wankel

                                  The German Engineer and Inventor, Felix Wankel Father of The Rotary-Engine. Felix Wankel was born in 1902 on August 13 In Lahr, Germany. He went to high schools in Donaueschingen, Heidelberg, and Weinheim, and left school without a Degree in 1921. He worked in a publishing house until June 1926. He and his friends were already running a small workshop in a backyard shed. Wankel was interested in the world of machines since he was a kid. At age 17 he told friends that he had dreamt of constructing a car with "a new type of engine, half turbine, half reciprocating. It is my invention!".

                                                                                            He came up with the design of the Wankel Rotary Engine. He managed to convince Rotary Engine in 1924 to win his first patent in 1929. The Rotary Engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. Compared to the piston engine, the Rotary engine had more uniform torque and less vibration and, for a given power, is more compact and weighs less.

Neckarsulmer Strickmachine Union

                                    Felix Wankel was searching for a company to help him improve and produce The Rotary Engine, The first company to agree to build The Rotary Engine with Felix was NSU (Neckarsulmer Strickmachine Union). His first task at NSU was to build a "super-charger" for a 50cc bike engine that is used to set a new speed record for motorcycles. His creation was a belt-driven Rotary compressor. Which boosted its performance. After building that Felix Wankel went onto building a Rotary Engine.

DKM 54 engine

                                                    NSU went onto making the rotary engine and came up with an experimental unit called DKM 54 engine. Testing on the DKM 54 Began in January 1957, Sadly Felix wasn't invited because the NSU didn't like his personality. On February 1 1957 In the third try, The Engine ran for the first time. It survived a 100 hours of testing. At first, it made 15hp at 9000 rpm. At the end of testing it was making 29hp at 17000 rpm, engine diameter only about 260 mm, shaft offset 9.5 mm. Three spark plugs rotated with the inner rotor. 4 Units were built only one is left in The Neckarsulm (Germany) Museum.

KKM engine (Kreiskolbenmotor)

                                                                                       Even though the visionary behind the rotary engine was Felix. The person who took Wankel's design and made it simpler and more practical was NSU engineer Walter Froede. In 1958 he came up with a Rotary engine basic design that was very similar to today's Rotary Engines, He mounted a single rotor inside a stationary housing, This inner rotor was mounted on an eccentric shaft that also was an output shaft. and he improved the rotor seals. This was a huge improvement when compared to what Felix Wankel had.

"Felix Wankel is reported to have said that they had transformed his racing horse into a cart horse."

 

                                                                                       They made two engine types and successfully tested them In 1958. This confirmed how efficient the KKM design was when compared to Felix Wankel's Between 1960 and 1964 they developed a lot of prototypes and installed it into a variety of machinery from lawn movers to boats.

                          The result of lots of testing and improvements was KKM 500. which later became an optional engine in the NSU Spyder as type 502. However, introducing this to the public was a delay because of serious technical problems that came from the gas and oil sealing and other components.

                          By now the Wankel Rotary Engine was a lot powerful, smooth, and was able to easily manufacture. As the word of Rotary Engine started spreading other manufacturers started showing interest, but to manufacture there own rotary engine license was required from NSU. At this time NSU was running out of money, NSU decided to sell the license to The Rotary Engine. The first company to buy the license by signing a multi-million dollar deal was Curtis-Wright an aircraft engine manufacturing company. They developed a Rotary Powered Aircraft. They never produced a four-wheel rotary-powered vehicle but this sparked more interest in other manufacturers.

Curtis-Wright Rotary Aircraft Engine

                          Automobile Manufacturers Started rushing in to buy the license of The Rotary Engine. Within a glimpse 20 licenses were issued and everyone had a license. Suzuki, Yamaha, Ford, Porsche, Nissan, Toyota, AMC, Alfa Romeo, M-Benz, VW, Citroen, GM, Ford,   was one of them. Every company went on there own way. But NSU required license holders to share research results with all others. Each manufacturer developed there own rotary engine, soon The Rotary Engine was called "The Engine Of The Future".

1972 GM Rotary engine cutaway shows twin-rotors

                          Every manufacturer's aim was to build their own version of The Rotary Engine, Ford went ahead and put the Curtis-Wright Aircraft Engine into a 1965 Mustang. GM went far as establishing a separate Division called GMRE (General Motors Rotary Engine). GM had big plans for the rotary, they were going to install it on Chevy Monza, Vega, Even a Four-Rotor 73' Corvette. Even the AMC had planned on putting a Rotary Engine on the AMC pacer. Benz had planned on a 3 and 4-Rotor Cars. Toyota and Nissan Failed! The concept never came out of the drawing board. Even after this much effort put in non of these companies was successful enough to produce a Production-ready Rotary Engine.

NSU Spider

                           NSU sold Wankel Spyder from 1964-1967, NSU tested the Rotary Engine in 1960, Later that year they showed their vision to the general public. The production NSU Spider was unveiled at the 1963 Frankfurt Automobile Show and was the first car to be powered by a Wankel rotary engine. There were two versions of the NSU Prinz. A hardtop 2 cylinder powered 598cc and Single rotor 498 cc Rotary powered convertible called Spyder. Their primary target was the motoring enthusiast. Specially tuned Spyders were also serious competition cars and gained titles at rally's and hill-climb races.2375 units were sold. 

                    As Automobile Manufacturers were giving up hopes on the rotary engine one company never gave hope on the rotary engine, That company was Toyo Kogyo they bought license No. 4 from NSU. They kept on developing and improving the Rotary Engine and successfully manufacturing. This improved rotary engines used carbon aluminum apex seals, dual spark plugs, a side port intake design, and twin rotors.

                    By the 1970s, the Japanese automotive manufacturer's eyes were on the US market, It was a huge market but quite a complicated one. Americans were driving huge cars with huge displacements, and they had 3 huge competitors Ford, GM, Chrystler. Pitching Americans in this huge market with this huge 3 competitors was crazy, odds were against them. It wasn't a good decision for a Toyo Kogyo to export without a guarantee. But Toyo Kogyo exported to the US shores. Toyo Kogyo wanted to appear more towards Americans and they decided to make a separate brand for importing cars to the US and called it MAZDA.

            Toyo Kogyo made a special division for the American market called Mazda with few people they got to work, They came up with several cars that are targeted towards the US market. The first cars to import to US shores were The R100 Familia and Rx-2. were the R100, Familia (the Japanese 1200cc-piston-powered R100), 1800, piston-powered RX-2. Mazda Kept on struggling for the first few years. After a few years as more and more Americans started buying, Americans started loving these small Japanese econoboxes, Especially they loved the Rotary powered cars. But sadly Mazda didn't have time to celebrate their victory. 1973 Gas crisis started. At the same pace, they grew they fell apart.

                                Rotary powered Mazdas were called gas-burners, Yes! It was not a valid statement when compared to the V8's. But Mazda kept on exporting cars to the US, The Rx-2 and Rx-3's weren't hits but, the Rx-4 was still it was unreliability, had poor gas mileage. But it had the most powerful Rotary-Engine to that day The 13B. The next few years were okay for Mazda. Then they introduced The 1976 Cosmo total failure in the US but in japan they loved it. Still, Mazda wasn't adapted to the US market and they had a shortage of money. In 1977 Mazda exported Mazda GLS It was a huge hit in the US market. Mazda earned a good reputation and money.

                        By now Mazda had money and confidence and at this time the gas crisis was almost over, What is a good time than this to bring Mazdas dream Rotary-Powered sports coupe. At this point, everyone thought Mazda is over in US shores but by introducing the Rx-7 in 1978 they proved they were wrong. With the release of Rx-7 Mazda was standing there with the big boys.

Note! I wanna keep this post short, so I'm not going to go in-depth about all the vehicles Mazda produced and jump straight into talking about the RS-X Prototype.

                    Mazda finally had there chance to come uptake the rotary concept from the drawing board to prototype, At this time Mazda had Few models of the RS-X concept. X020A and X020G Prototypes. But Mazda had a problem their idea was to take the existing Rx-5 cosmo chassis and modifying it a little bit to suit there needs. Mazda still didn't understand the American market, So they packed there bags and went themselves to the US shores. They did surveys and a lot of research they came back and went back to the drawing board, This time they exactly knew what they were designing. They engineered this car from scratch with the sole purpose of putting a rotary engine, They came up with an extremely rigid unibody design and named it X605. They installed a more improved 12A Rotary Engine in it. Finally, they Archived what they dreamed of since the beginning, The Legendary Rotary Powered Rx-7 was born.

                It didn't take too long to go from drawing board to the production-ready car. When they introduced Rx-7 to the US market in 1979, Waiting lists were filled. Rx-7 was cheaper than all the cars that came in that period. It had good power to weight ratio and good weight distribution. It was a pleasure to drive an Rx-7 and with its power, you can easily outrun a Porsche 924 or a Datsun 280Z. Rx-7 sold for less than 7grand. After that, not many changes happen to the car other than a few trim levels.

                                In 1984 out came the Rx-7 FB, The car that is made for the car enthusiasts. Mazda made a more refined 1308cc Naturally Asperated engine, With a larger combustion chamber and wider block. The new engine had 6 intake ports at 5000rpm the 2 new intake ports will be opened this allowed the engine to be tuned to your favor of performance. Out came the 13B this engine was more reliable and capable of modifying. These changes gave the 13B more torque and horsepower. With the correct modification, an N/A 13B was capable of making 200hp. This engine with a Limited slip differential, bigger 4 wheel disk breaks, bigger calipers, A improved 5-speed transmission, suspension improvements, 14x5.5" alloy wheels with 205/60/14 tires. All these upgrades made this car was "The ultimate handling machine". This GSL-SE boosted the Rx-7 sales off the roof since the next-generation release.

                                  In 1986, Mazda came up with the second generation, The next second-generation Rx-7 FC, had a more powerful engine and was more good looking. Completely a different car from the first-generation. Three different prototypes were built under the name P747. Goals were to improve aero, power, handling, and reliability. A totally newly designed suspension with a build-in PSEUDO 4 Wheel Steering. Mazda was on the right track when they were building this car because. They added the DTSS (Dynamic Tracking Suspension System). A special front axle and bushing design was made to toe in when the car does a pull. This DTS system kept negative camber in the rear wheels even when cornering. If you race rear-wheel-drive cars you know this is the dream of any RWD race car drivers.

                The engine had upgrades. Newly updated 3 piece apex seals instead of the older once. Lightweight rotors. Another injector was added to the intake to get more gas mileage and power. The Oil-injection system was redesigned The oil will be directly sprayed to the intake manifold and the trochoidal chamber. Rx7 was fitted with a rack and pinion steering system. With all these upgrades the car handled like a dream. Americans loved the FC more than the FB, making it the best sold in RX-7 history, with more than 56k units sold in the United States alone. With the release of the 2nd gen Rx7 prices of the 1st generation dropped that meant you were able to buy an Rx7 FB or a SA for very cheap. 

                        During this second-generation Rx7's run, a few special models were released. Basic Rx7, GXL, and SE. In 1988 GTU model was released to celebrate the domination of the Rx7 in IMSA. There was a GXL model that was released as the luxury performance model. 

And in 1988, Mazda produced another model celebrating the 10th year in the USA called the 10th anniversary edition. 

            Rx7 Fc3s Turbo 2. Finally in 1987 Mazda made a Turbo version of the Rx7 to the US market. In 1991 Mazda Released a new Rx7 right before they released the FD 3rd gen Rx7. Mazda went all out on this they made it lighter and more powerful. It was called ɛ̃fini IV. The RX-7 Infini IV Turbo charged 2.6l 13B. With a 5 speed manual gearbox. The Mazda RX-7 Infini IV weighed around 1256 kg.

                        Third gen rx7 known as Rx7 FD came to the market in 1993. This car was the peak of the Rx7. One of the most beautifulest and iconic cars ever to come from japan. When people say Rotary or Rx7 the first thing comes to mind is the Rx7 FD. A completely Re-engineereed 13B power plant boasted by a Hitchi turbochargers. A large turbo intercooler and, in the "R" version, dual oil coolers located at each front end corners of the car. Rx7 came with a sequential turbocharging system. Which gave off the line performance. 13B made 255bhp 217 ft-lbs of torque out of just 1.3 liters. That's sick as fuck! It only weighed 1270Kg, That meant the FD had a great power to weight ratio. There was the base model. Then a touring package.