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133-589: The Mazda Wankel engines are a family of Wankel rotary combustion car engines produced by Mazda . Wankel engines were invented in 1950s by Felix Wankel , a German engineer. Over the years, displacement has been increased and turbocharging has been added. Mazda rotary engines have a reputation for being relatively small and powerful at the expense of poor fuel efficiency . The engines became popular with kit car builders, hot rodders and in light aircraft because of their light weight, compact size, tuning potential and inherently high power-to-weight ratio —as

266-513: A leaf-sprung de Dion tube . Unassisted 10 inch (254 mm) disk brakes were found in front with 7.9 inches (201 mm) drum brakes in the rear. Performance in the quarter-mile (400 m) was 16.4 s, with a 115 mph (185 km/h) top speed. The price was lower than the Toyota 2000GT at 1.48 million yen (US$ 4,100). The Series II/L10B was introduced in July 1968. It had

399-781: A manual transmission . Not all two-door 929 models used the FET, most used other variants of the FE engine, either Carburetor or EGI with optional four-speed automatic transmission. The 2.0 L (1998 cc) fuel injected , turbocharged FET version of the FE produced 135 hp (100 kW) and 175 lb·ft (237 N·m). It was a water cooled 8-valve SOHC engine featuring a small turbocharger, and no intercooler . Series I Models for Japan (1981-1983) Coupé and Hardtop: Saloon Series II Models for Japan (1983-1989) Coupé and Hardtop: Saloon (1984-1986): The Eunos Cosmo (loosely based on

532-414: A piston engine . The displacement of rotor can be calculated as Note that this only counts a single face of each rotor as the entire rotor's displacement, because with the eccentric shaft – crankshaft – spinning at three times the rate of the rotor, only one power stroke is created per output revolution , thus only one face of the rotor is actually working per "crankshaft" revolution, roughly equivalent to

665-444: A 2-stroke engine of similar displacement to a single rotor face. Nearly all Mazda production Wankel engines share a single rotor radius, 105 mm (4.1 in), with a 15 mm (0.59 in) crankshaft offset. The only engine to diverge from this formula was the rare 13A , which used a 120 mm (4.7 in) rotor radius and 17.5 mm (0.69 in) crankshaft offset. As Wankel engines became commonplace in motorsport ,

798-576: A Wankel engine are thus mainly limited by tooth load on the synchronizing gears. Hardened steel gears are used for extended operation above 7,000 or 8,000   rpm. In practice, automotive Wankel engines are not operated at much higher output shaft speeds than reciprocating piston engines of similar output power. Wankel engines in auto racing are operated at speeds up to 10,000   rpm, but so are four-stroke reciprocating piston engines with relatively small displacement per cylinder. In aircraft, they are used conservatively, up to 6500 or 7500   rpm. In

931-405: A Wankel rotary engine, the chamber volume V k {\displaystyle V_{k}} is equivalent to the product of the rotor surface A k {\displaystyle A_{k}} and the rotor path s {\displaystyle s} . The rotor surface A k {\displaystyle A_{k}} is given by the rotor tips' path across

1064-400: A Wankel rotary engine, the eccentric shaft must make three full rotations (1080°) per combustion chamber to complete all four phases of a four-stroke engine. Since a Wankel rotary engine has three combustion chambers, all four phases of a four-stroke engine are completed within one full rotation of the eccentric shaft (360°), and one power pulse is produced at each revolution of the shaft. This

1197-399: A boundary layer from overheating working parts. The University of Florida proposed the use of heat pipes in an air-cooled Wankel to overcome this uneven heating of the block housing. Pre-heating of certain housing sections with exhaust gas improved performance and fuel economy, also reducing wear and emissions. The boundary layer shields and the oil film act as thermal insulation, leading to

1330-559: A butterfly valve for low- and high-RPM use (respectively) Applications: The improved 0813 engine appeared in July 1968 in the Series II/L10B Cosmo . Its construction was very similar to the 0810 . Japanese-spec gross output was 100 hp (75 kW) at 7000 rpm and 133 N⋅m (98 lbf⋅ft) at 3500 rpm. The use of less-expensive components increased the mass of the engine from 102 to 122 kg (225 to 269 lb). Applications: The final member of

1463-534: A formal pillared sedan (known in Japan as saloon). The HB Cosmo is the only car in automotive history to offer a choice of gasoline and diesel piston engines, or rotary engines, and this was the last generation Cosmo to be exported. Both the Cosmo sedan and four door hardtops were badge engineered versions of their respective Luce counterparts, with the Cosmo models sold at an exclusive dealership called Mazda Auto , while

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1596-406: A fresh air supply to the exhaust port. It also proved that a Reed-valve in the intake port or ducts improved the low rpm and partial load performance of Wankel engines, by preventing blow-back of exhaust gas into the intake port and ducts, and reducing the misfire-inducing high EGR, at the cost of a slight loss of power at top rpm. Elasticity is improved with a greater rotor eccentricity, analogous to

1729-414: A generator for the 2023 MX-30 e-Skyactiv R-EV plug-in hybrid . Wankel engines can be classified by their geometric size in terms of radius (rotor center to tip distance, also the median stator radius) and depth (rotor thickness), and offset (crank throw, eccentricity, also 1/4 the difference between stator's major and minor axes). These metrics function similarly to the bore and stroke measurements of

1862-439: A glow-plug for the leading site spark plug improved low rpm, part load, specific fuel consumption by 7%, and emissions and idle. A later alternative solution to spark plug boss cooling was provided with a variable coolant velocity scheme for water-cooled rotaries, which has had widespread use, being patented by Curtiss-Wright, with the last-listed for better air-cooled engine spark plug boss cooling. These approaches did not require

1995-431: A high incidence of sealing loss, both between the rotor and the housing and also between the various pieces making up the housing. Also, in earlier model Wankel engines, carbon particles could become trapped between the seal and the casing, jamming the engine and requiring a partial rebuild. It was common for very early Mazda engines to require rebuilding after 50,000 miles (80,000 km). Further sealing problems arose from

2128-441: A high-conductivity copper insert, but did not preclude its use. Ford tested a Wankel engine with the plugs placed in the side plates, instead of the usual placement in the housing working surface ( CA 1036073   , 1978). Wankel engines are capable of high-speed operation, meaning they do not necessarily need to produce high torque to produce high power. The positioning of the intake port and intake port closing greatly affect

2261-423: A longer stroke in a reciprocating engine. Wankel engines operate better with a low-pressure exhaust system. Higher exhaust back pressure reduces mean effective pressure, more severely in peripheral intake port engines. The Mazda RX-8 Renesis engine improved performance by doubling the exhaust port area relative to earlier designs, and there have been studies of the effect of intake and exhaust piping configuration on

2394-412: A low temperature of the lubricating film (approximate maximum 200 °C or 390 °F on a water-cooled Wankel engine). This gives a more constant surface temperature. The temperature around the spark plug is about the same as in the combustion chamber of a reciprocating engine. With circumferential or axial flow cooling, the temperature difference remains tolerable. Problems arose during research in

2527-406: A more steady idle, because it helps to prevent blow-back of burned gases into the intake ducts, which cause "misfirings" caused by alternating cycles where the mixture ignites and fails to ignite. Peripheral porting (PP) gives the best mean effective pressure throughout the rpm range, but PP was also linked to worse idle stability and part-load performance. Early work by Toyota led to the addition of

2660-409: A more-powerful 128 hp (95 kW)/103 lb·ft (140 N·m) 0813 engine, power brakes, 15 inch wheels and a 5-speed manual transmission . The wheelbase had been expanded by 15cm for more room and a better ride. This Cosmo was good for over 120 mph (193 km/h) and could accelerate to cover a quarter-mile (400 m) in 15.8 s. Visual changes included a larger grille under

2793-531: A result of the poor efficiency, a Wankel engine with peripheral exhaust porting has a larger amount of unburnt hydrocarbons (HC) released into the exhaust. The exhaust is, however, relatively low in nitrogen oxide (NOx) emissions, because the combustion is slow, and temperatures are lower than in other engines, and also because of the Wankel engine's good exhaust gas recirculation (EGR) behavior. Carbon monoxide (CO) emissions of Wankel and Otto engines are about

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2926-513: A rotary internal combustion engine with Felix Wankel, based upon Wankel's supercharger design for their motorcycle engines. Since Wankel was known as a "difficult colleague", the development work for the DKM was carried out at Wankel's private Lindau design bureau. According to John B. Hege, Wankel received help from his friend Ernst Höppner, who was a "brilliant engineer". The first working prototype, DKM 54 (see figure 2.), first ran on 1 February 1957, at

3059-498: A single-rotor Wankel engine produces the same average power as a V h {\displaystyle V_{h}} single-cylinder two-stroke engine , with the same average torque, with the shaft running at the same speed, operating the Otto cycles at triple the frequency. Richard Franz Ansdale, Wolf-Dieter Bensinger and Felix Wankel based their analogy on the number of cumulative expansion strokes per shaft revolution. In

3192-533: A space for a more powerful piston-engined derivative, as rotary sales were slowing down because of their high fuel consumption, the bigger Cosmo 2000 with 110 PS (81 kW) became available in March 1977. The rotary engine had financial advantages to Japanese consumers in that the engine displacement remained below 1.5 liters, a significant determination when paying the Japanese annual road tax which kept

3325-403: A stationary center shaft, the DKM engine was impractical. Wolf-Dieter Bensinger explicitly mentions that proper engine cooling cannot be achieved in a DKM engine, and argues that this is the reason why the DKM design had to be abandoned. NSU development chief engineer Walter Froede solved this problem by using Hanns-Dieter Paschke's design and converting the DKM into what would later be known as

3458-525: A strong housing, the old carbon seals could be abandoned in favour of conventional cast iron. Early 12A engines also feature a thermal reactor, similar to the 0866 10A, and some use an exhaust port insert to reduce exhaust noise. A lean-burn version was introduced in 1979 (in Japan) and 1980 (in America) which substituted a more-conventional catalytic converter for this "afterburner". A major modification of

3591-456: A thermal reactor or catalyst converter may be used to reduce hydrocarbon and carbon monoxide from the exhaust. Mazda uses a dual ignition system with two spark plugs per chamber. This increases the power output and at the same time reduces HC emissions. At the same time, HC emissions can be lowered by reducing the pre-ignition of the T leading plug relative to the L trailing plug. This leads to internal afterburning and reduces HC emissions. On

3724-425: A thin dimensional galvanized chrome layer. This allowed Mazda to return to the 3mm and later even 2mm thick metal apex seals. Another early problem was the build-up of cracks in the stator surface near the plug hole, which was eliminated by installing the spark plugs in a separate metal insert/ copper sleeve in the housing instead of a plug being screwed directly into the block housing. Toyota found that substituting

3857-614: A trial basis 40-octane gasoline was produced by BV Aral, which was used in the Wankel DKM54 test engine with a compression ratio of 8:1; it ran without complaint. This upset the petrochemical industry in Europe, which had invested considerable sums of money in new plants for the production of higher quality gasoline. Direct injection stratified charge engines can be operated with fuels with particularly low octane numbers. Such as diesel fuel, which only has an octane number of ~25. As

3990-465: A two-level intake box which derived a supercharger -like effect from the Helmholtz resonance of the opening and closing intake ports. The RESI engine also featured Bosch L-Jetronic fuel injection . Output was much improved at 135 PS (99 kW) and 180 N⋅m (133 lbf⋅ft). Applications: Like the 12A-SIP, the second-generation RX-7 bowed with a variable-intake system. Dubbed DEI ,

4123-720: Is a further Series II Cosmo in a collection in Alberta, Canada. A 1970 Mazda Cosmo Sport Series II L10B Coupe sold in January 2015 for US$ 110,000 inclusive premium at auction at Bonhams . A 1970 Mazda Cosmo Series II 110S is currently, (September 2024), being fully restored by an English based Company called Yorkshire Car Restorations on YouTube. It has the original Wankel engine (10A) and original 5-speed gearbox. It has been fully stripped to bare metal and new re-fabricated parts and panels fitted, where necessary. The second generation CD Cosmo appeared in 1975 and lasted until 1981. It

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4256-558: Is depicted in figure 7. Seals at the rotor's apices seal against the housing's periphery. The rotor moves in its rotating motion guided by gears and the eccentric output shaft, not being guided by the external chamber. The rotor does not make contact with the external engine housing. The force of expanded gas pressure on the rotor exerts pressure on the center of the eccentric part of the output shaft. All practical Wankel engines are four-cycle (i.e., four-stroke) engines. In theory, two-cycle engines are possible, but they are impractical because

4389-428: Is described in the thermodynamic disadvantages section , the early Wankel engines had poor fuel economy. This is caused by the Wankel engine's design of combustion chamber shape and huge surface area. The Wankel engine's design is, on the other hand, much less prone to engine knocking, which allows using low- octane fuels without reducing compression. NSU tested low octane gasoline at the suggestion of Felix Wankel. On

4522-440: Is different from a four-stroke piston engine, which needs to make two full rotations per combustion chamber to complete all four phases of a four-stroke engine. Thus, in a Wankel rotary engine, according to Bensinger, displacement ( V h {\displaystyle V_{h}} ) is: If power is to be derived from BMEP, the four-stroke engine formula applies: Eugen Wilhelm Huber, and Karl-Heinz Küttner counted all

4655-412: Is in studying the number of rotations for a thermodynamic cycle to occur. For a 4-cycle engine to complete a thermodynamic cycle, the engine must rotate two complete revolutions of the crankshaft, or 720°. By contrast, in a Wankel engine, the engine rotor rotates at one-third the speed of the crankshaft. Each rotation of the engine (360°) will bring two faces through the combustion cycle (the torque input to

4788-414: Is the dominant source of hydrocarbon at high speeds and leakage at low speeds. Using side-porting which enables closing the exhaust port around the top-dead center and reducing intake and exhaust overlap helps improving fuel consumption. Mazda Cosmo The Mazda Cosmo ( マツダ・コスモ , Matsuda Kosumo ) is an automobile which was produced by Mazda from 1967 until 1996. Throughout its history,

4921-397: Is the number of chambers considered for each rotor and i {\displaystyle i} the number of rotors, then the total displacement is: If p m e {\displaystyle p_{me}} is the mean effective pressure , N {\displaystyle N} the shaft rotational speed and n c {\displaystyle n_{c}}

5054-463: Is true for all Wankel-type engines. Since the end of production of the Mazda RX-8 in 2012, the engine was produced only for single seater racing , with the one-make Star Mazda Championship being contested with a Wankel engine until 2017; the series' transition to using a Mazda-branded piston engine in 2018 temporarily ended the production of the engine. In 2023, Mazda reintroduced the engine as

5187-596: The Cosmo L in Japan, it included an opera window and padded vinyl roof covering. Neither body style found many international buyers; it was, however, an enormous success in Japan where over 55,000 were sold in the first year alone. This new model competed with the Toyota Crown , Nissan Cedric , Nissan Gloria , and the Mitsubishi Galant Lambda coupés newly introduced to Japan. Mazda America used

5320-631: The NSU Spider at the Frankfurt Motor Show ; 80 pre-production Cosmos were produced for the Mazda test department (20) and for dealership testing (60) between 1965 and 1966. Full production began in May 1967 and lasted through 1972, though Cosmos were built by hand at a rate of only about one per day, for a total of 1,176 (343 Series I cars and 833 Series II cars). The car was also featured in

5453-411: The 10A family was the 1971 0866 . This variant featured a cast-iron thermal reactor to reduce exhaust emissions and re-tuned exhaust ports. The new approach to reducing emissions was partly a result of Japanese Government emission control legislation in 1968, with implementation starting in 1975. Mazda called their technology REAPS ( R otary E ngine A nti P ollution S ystem). The die-cast rotor housing

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5586-475: The 12A architecture was the 6PI which featured variable induction ports. Applications: The ultimate 12A engine was the electronically fuel-injected engine used in the Japan-spec HB series Cosmo , Luce , and SA series RX-7 . In 1982 a 12A turbo powered Cosmo coupe was officially the fastest production car in Japan. It featured "semi- direct injection " into both rotors at once. A passive knock sensor

5719-407: The 13A. Instead, it is a lengthened version of the 12A, having 80 mm (3.1 in) thick rotors. It was a two-rotor design, with each chamber displacing 654 cc (39.9 cu in) so two chambers (one per rotor) would displace 1.3 L (1,308 cc); the series name reflects this value ("13" suggesting 1.3 litres), as with the 13A of the same displacement but different proportions. In

5852-439: The 13B, the 13B-REW , became famous for its high output and low weight. The turbos were operated sequentially, with only the primary providing boost until 4,500 rpm, and the secondary additionally coming online afterwards. Notably, this was the world's first volume-production sequential turbocharger system. Output eventually reached, and may have exceeded, Japan's unofficial maximum of 280 PS (206 kW; 276 hp) DIN for

5985-594: The 1950s and 1960s. For a while, engineers were faced with what they called "chatter marks" and "devil's scratch" in the inner epitrochoid surface, resulting in chipping of the chrome coating of the trochoidal surfaces. They discovered that the cause was the apex seals reaching a resonating vibration, and the problem was solved by reducing the thickness and weight of the apex seals as well as using more suitable materials. Scratches disappeared after introducing more compatible materials for seals and housing coatings. Yamamoto experimentally lightened apex seals with holes. Now, weight

6118-454: The 1969–1972 R130 Luce , where it produced 126 PS (93 kW) and 172 N⋅m (127 lbf⋅ft). This was the end of the line for this engine design: the next Luce was rear-wheel drive and Mazda never again made a front-wheel drive rotary vehicle. Applications: The 12A is an "elongated" version of the 10A: the rotor radius was the same, but the depth was increased by 10 mm (0.39 in) to 70 mm (2.8 in). It continued

6251-521: The 1985 MX-03 concept car ) started production in 1990 on the new JC platform . The Eunos Cosmo was the top-line touring flagship of the Eunos luxury channel. It is the only Mazda to use a triple-rotor engine. The car was a 2+2 coupé and was loaded with power amenities and other luxuries. Following the Japanese luxury theme, only an electronically controlled 4-speed automatic transmission was available that could be placed in manual shift mode and would change

6384-502: The 20B-REW version was capable of 255 km/h (158.4 mph) if given a free run. With over 380 N⋅m (280 lb⋅ft) of torque available at just 1,800 rpm, the Cosmo could launch from standstill to freeway speeds quickly; however, this came at the expense of heavy fuel consumption. The JC Cosmo was expensive even by today's standards, as Mazda still has not matched the sales price of this car some 22 years later for anything else in its range. The availability of power and speed in

6517-486: The 4 port intake design similar to what was used in the '74–'78 13B. In '86–'88 engines the twin-scroll turbocharger is fed using a two-stage mechanically actuated valve, however, on '89–'91 engines a better turbo design was used with a divided manifold powering the twin-scroll configuration. For engines manufactured between '86-'88 output is rated at 185 PS (136 kW) at 6500 rpm and 248 N⋅m (183 lbf⋅ft) at 3500 rpm. Applications: The 13B-RE from

6650-580: The 929 being the export version (which was not available with the rotary engine options). While the HB Luce and Cosmo Saloon were discontinued in 1986, both Cosmo hardtops remained in production at a trickle until 1989. The Mazda 929 Turbo EGI (Electronic Gasoline Injection) Luxury was available in Australia from 1986 to May 1987 (with these later cars produced in 1986). It used the FET engine and came only with

6783-507: The Cosmo appears extravagant in its intended market of Japan once it becomes understood that most of the driving environment consists of two-way streets that are usually zoned at 40 km/h (25 mph) or less, as mentioned in the article Speed limits in Japan The Cosmo was manufactured from February 1990 until September 1995, and gathered a total of 8,875 sales. A split of 60/40 sales between 13B-REW and 20B-REW variants made

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6916-590: The Cosmo served as a " halo " vehicle for Mazda, with the first Cosmo successfully launching the Mazda Wankel engine . The final generation of Cosmo served as Mazda's flagship vehicle in Japan, being sold as the Eunos Cosmo through its luxury Eunos division in Japan. Mazda chose to use the name " cosmo " , reflecting international cultural fascination with the Space Race , as Mazda wanted to showcase

7049-550: The DKM engine were built; the design is described to have a displacement V h of 250 cm (equivalent to a working chamber volume V k of 125 cm ). The fourth unit built is said to have received several design changes, and eventually produced 29 PS (21 kW) at 17,000 rpm; it could reach speeds up to 22,000 rpm. One of the four engines built has been on static display at the Deutsches Museum Bonn (see figure. 2). Due to its complicated design with

7182-723: The FC series Mazda Savanna RX-7 was introduced in 1986 internationally, this series Cosmo coupe retained its top position as Mazda's largest rotary powered personal luxury car , with a comfortable backseat, trunk, and every luxury amenity available, while adopting the retractable headlights from the RX-7. Mazda offered three different rotary engines for the HB series. A 12A-6PI (for "six-port induction"), 12A-turbo and 13B-RESI, with all using electronic multiport fuel injection. The latter available with automatic transmission only. The 1982 12A-turbo Cosmo coupé

7315-485: The JC Cosmo series was a similar motor to the 13B-REW but had a few key differences, namely it being endowed with the largest side ports of any later model rotary engine. Injector sizes = 550 cc (34 cu in) PRI + SEC. Approximately 5000 13B-RE optioned JC Cosmos were sold, making this engine almost as hard to source as its rarer 20B-REW big-brother. Applications: A sequentially-turbocharged version of

7448-508: The KKM (see figure 5.). The KKM proved to be a much more practical engine, as it has easily accessible spark plugs, a simpler cooling design, and a conventional power take-off shaft. Wankel disliked Froede's KKM engine because of its inner rotor's eccentric motion, which was not a pure circular motion, as Wankel had intended. He remarked that his "race horse" was turned into a "plough horse". Wankel also complained that more stresses would be placed on

7581-460: The KKM type. Felix Wankel designed a rotary compressor in the 1920s, and received his first patent for a rotary type of engine in 1934. He realized that the triangular rotor of the rotary compressor could have intake and exhaust ports added producing an internal combustion engine. Eventually, in 1951, Wankel began working at German firm NSU Motorenwerke to design a rotary compressor as a supercharger for NSU's motorcycle engines. Wankel conceived

7714-488: The KKM ;502 was a powerful engine with decent potential, smooth operation, and low noise emissions at high engine speeds. It was a single-rotor PP engine with a displacement of 996 cm (61 in ), a rated power of 40 kW (54 hp) at 6,000   rpm and a BMEP of 1 MPa (145 lbf/in ). The Wankel engine has a spinning eccentric power take-off shaft, with a rotary piston riding on eccentrics on

7847-510: The KKM's apex seals due to the eccentric hula-hoop motion of the rotor. NSU could not afford to finance developing both the DKM and the KKM, and eventually decided to drop the DKM in favor of the KKM, because the latter seemed to be the more practical design. Wankel obtained the US patent 2,988,065 on the KKM engine on 13 June 1961. Throughout the design phase of the KKM, Froede's engineering team had to solve problems such as repeated bearing seizures,

7980-637: The Luce was sold at previously established Japanese Mazda dealerships. Later in 1991, Mazda Auto locations were renamed Eunos . The two door HB coupé however was only sold in Japan as a Cosmo. The range was facelifted in October 1983, at which time the fuel injected 13B-SI engine was introduced and the four-door hardtop switched from pop-up to fixed headlights. During 1984, the non-GT coupés also switched to fixed headlamps (domestic Japanese market; export markets differ in specifications and badge combinations). When

8113-651: The Mazda Cosmo name and offered it from 1976 through 1978, fitted with the 13B rotary engine. In the United States, the Cosmo was replaced by the smaller, lighter, and sportier Mazda RX-7 . Due to its poor sales as an export, the Series II version, built from 1979, was not exported and remained a Japanese domestic sale only. In Europe, the RX-5 saw very little competition in the rotary-engine equipped market, with

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8246-547: The NSU research and development department Versuchsabteilung TX . It produced 21 PS (15 kW). Soon after that, a second prototype of the DKM was built. It had a working chamber volume V k of 125 cm and also produced 21 kW (29 PS) at 17,000   rpm. It could even reach speeds of up to 25,000   rpm. However, these engine speeds distorted the outer rotor's shape, thus proving impractical. According to Mazda Motors engineers and historians, four units of

8379-436: The S (Sport) which offered a firm suspension consisting of control arms in the front and a multilink rear suspension, with a cloth inserts added to leather interior and a full length center console accommodating four passengers, or E (Elegant) which offered a softer-tuned suspension and full leather upholstery. The JC series Cosmo set several firsts in automotive history. Its two rotor 13B-RE and three rotor 20B-REW engines were

8512-444: The U.S. to finish the 24 hours of Le Mans (and in 1991 Mazda won the race outright with the 4-rotor R26B engine). In 1974, a new process was used to harden the rotor housing. The Sheet-metal Insert Process (SIP) used a sheet of steel much like a conventional piston engine cylinder liner with a chrome plated surface. The side housing coating was also changed to eliminate the troublesome sprayed metal. The new "REST" process created such

8645-580: The United States, the 13B was available from 1974 to 1978 and was then retired from sedans but continued in 1984–1985 RX-7 GSL-SE. It was then used from 1985 to 1992 in the RX-7 FC, in Naturally Aspirated or Turbocharged options, then once again in the RX-7 FD in a twin turbocharged form from 1992. It disappeared from the US market again in 1995, when the last US-spec RX-7s were sold. The engine

8778-443: The Wankel engine run much smoother. This is because the Wankel engine has a lower moment of inertia and less excess torque area due to its more uniform torque delivery. For example, a two-rotor Wankel engine runs more than twice as smoothly as a four-cylinder piston engine. The eccentric output shaft of a Wankel engine also does not have the stress-related contours of a reciprocating piston engine's crankshaft. The maximum revolutions of

8911-459: The arcade game series Wangan Midnight : Maximum Tune 1 through 6RR . At the 2002 Tokyo Auto Salon , Mazda presented the Cosmo 21, a retro styled 21st century reinterpretation of the original Cosmo 110s of 1967 to commemorate the 35th anniversary of the Cosmo. Based on Mazda's current generation of MX-5 (NB), the concept was styled and constructed by Mazda subsidiaries M'z IF (styling) and Mazda Sangyo (construction), and closely resembled

9044-613: The average torque, with the shaft running at 2/3 the speed, operating the Otto cycles at the same frequency: Applying a 2/3 gear set to the output shaft of the three-cylinder (or a 3/2 one to the Wankel), the two are analogous from the thermodynamic and mechanical output point of view, as pointed out by Huber. NSU licensed the Wankel engine design to companies worldwide, in various forms, with many companies implementing continual improvements. In his 1973 book Rotationskolben-Verbrennungsmotoren , German engineer Wolf-Dieter Bensinger describes

9177-422: The axially closer side housings in the cooler intake lobe areas was dealt with by using an axial rotor pilot radially inboard of the oils seals, plus improved inertia oil cooling of the rotor interior (C-W US 3261542   , C. Jones, 5/8/63, US 3176915   , M. Bentele, C. Jones. A.H. Raye. 7/2/62), and slightly "crowned" apex seals (different height in the center and in the extremes of seal). As

9310-407: The chambers, since each one operates its own thermodynamic cycle. So y = 3 {\displaystyle y=3} and n c = 3 {\displaystyle n_{c}=3} : With these values, a single-rotor Wankel engine produces the same average power as a V h {\displaystyle V_{h}} three-cylinder four-stroke engine, with 3/2 of

9443-553: The chatter mark problem. The first 10A engine was the 0810 , used in the Series I Cosmo from May 1965 to July 1968. These cars, and their revolutionary engine, were often called L10A models. Gross output was 110 hp (82 kW) at 7000 rpm and 130 N⋅m (96 lbf⋅ft) at 3500 rpm, but both numbers were probably optimistic (rpm of the crankshaft). The 10A featured twin side intake ports per rotor, each fed by one of four carburetor barrels. Only one port per rotor

9576-426: The design of a triangular rotor in the compressor. With the assistance of Prof. Othmar Baier  [ de ] from Stuttgart University of Applied Sciences, the concept was defined mathematically. The supercharger he designed was used for one of NSU's 50 cm one-cylinder two-stroke engines. The engine produced a power output of 13.5 PS (10 kW) at 12,000   rpm. In 1954, NSU agreed to develop

9709-430: The displacement per face is 654 cc (39.9 cu in), then four faces can be seen as equivalent to 2.6 L or 160 cu in. Extrapolating to the case of where three whole rotations is a complete thermodynamic cycle of the engine with a total of six faces completing a cycle, 654 cc (39.9 cu in) per face for six faces yields 3.9 L or 240 cu in. Mazda's first prototype Wankel

9842-448: The early days, unique, dedicated production machines had to be built for different housing dimensional arrangements. However, patented designs such as U.S. patent 3,824,746 , G. J. Watt, 1974, for a "Wankel Engine Cylinder Generating Machine", U.S. patent 3,916,738 , "Apparatus for machining and/or treatment of trochoidal surfaces" and U.S. patent 3,964,367 , "Device for machining trochoidal inner walls", and others, solved

9975-423: The eccentric shaft). This said, it takes three complete revolutions of the crankshaft, or 1080°, to complete the entire thermodynamic cycle. To get a relatable number to compare to a 4-stroke engine, compare the events that occur in two rotations of a two-rotor engine. For every 360° of rotation, two faces of the engine complete a combustion cycle. Thus, for two whole rotations, four faces will complete their cycle. If

10108-414: The engine features both the 6PI and DEI systems, as well as four-injector electronic fuel injection . Total output is up to 146 PS (107 kW) at 6500 rpm and 187 N⋅m (138 lbf⋅ft) at 3500 rpm. The 13B-T was turbocharged in 1986. It features the newer four-injector fuel injection of the 6PI engine, but lacks that engine's eponymous variable intake system and 6PI. Mazda went back to

10241-416: The engine's torque production. Early closing of the intake port increases low-end torque, but reduces high-end torque (and thus power). In contrast, late closing of the intake port reduces low-end torque while increasing torque at high engine speeds, thus resulting in more power at higher engine speeds. A peripheral intake port gives the highest mean effective pressure ; however, side intake porting produces

10374-431: The engine. While this puts great demands on the materials used, the simplicity of the Wankel makes it easier to use alternative materials, such as exotic alloys and ceramics . A commonplace method is, for engine housings made of aluminum, to use a spurted molybdenum layer on the engine housing for the combustion chamber area, and a spurted steel layer elsewhere. Engine housings cast from iron can be induction-brazed to make

10507-421: The experience gained, from carbon alloys, to steel, ferritic stainless , Ferro-TiC, and other materials. The combination of housing plating and the apex and side seal materials was determined experimentally, to obtain the best duration of both seals and housing cover. For the shaft, steel alloys with little deformation on load are preferred, the use of Maraging steel has been proposed for this. Leaded petrol fuel

10640-463: The factor that controls the amount of unburnt hydrocarbons in the exhaust is the rotor surface temperature, with higher temperatures resulting in fewer hydrocarbons in the exhaust. Curtiss-Wright widened the rotor, keeping the rest of engine's architecture unchanged, thus reducing friction losses and increasing displacement and power output. The limiting factor for this widening was mechanical, especially shaft deflection at high rotative speeds. Quenching

10773-404: The farthest, and a {\displaystyle a} as the shortest parallel transfer of the rotor and the inner housing and assuming that R 1 = R + a {\displaystyle R_{1}=R+a} and R 2 = R + a ′ {\displaystyle R_{2}=R+a'} . Then, Including the parallel transfers of the rotor and

10906-479: The final revision used in the Series 8 Mazda RX-7. Applications: Wankel engine In its basic gasoline fuelled form, the Wankel engine has lower thermal efficiency and higher exhaust emissions relative to the four-stroke reciprocating piston engine. The thermal inefficiency has restricted the engine to limited use since its introduction in the 1960s. However, many disadvantages have mainly been overcome over

11039-499: The first Japanese-built, series production twin sequential turbo systems to be offered for sale on a rotary engine car. The internationally known FD series RX-7 didn't receive the twin turbo 13B-REW engine until early 1992. The Eunos Cosmo was the first production car to have a built-in GPS navigation system , and the first in Japan to use the "Palmnet" serial data communication system for ECU-to-ECAT operation. The fourth generation Cosmo

11172-529: The following licensees, in chronological order, which is confirmed by John B. Hege: In 1961, the Soviet research organizations of NATI, NAMI, and VNIImotoprom began developing a Wankel engine. Eventually, in 1974, development was transferred to a special design bureau at the AvtoVAZ plant. John B. Hege argues that no license was issued to any Soviet car manufacturer. Felix Wankel managed to overcome most of

11305-560: The front bumper with two additional vents to each side of this "mouth". Only 833 were ever made, and fewer than six Series II models were initially imported into the United States . The price was up a bit to 1.48 million yen (US$ 4,390). Comedian and former talk show host Jay Leno owns a 1970 Series II Cosmo which was featured on the North American Speed Channel series My Classic Car in March 2006. It

11438-579: The gear selection in the dashboard display from PRNDSL for automatic transmission operation and PRND321 for manual transmission use. Two engines were available, and both were equipped with twin sequential turbochargers ; the two-rotor 13B-RE and the three-rotor 20B-REW . The triple rotor 20B had 2 litres (1962 cc) of displacement, making it the largest capacity rotary offered for sale by Mazda. It produces 280 PS (206 kW; 276 hp) and 403 N⋅m (297 lb⋅ft) of torque with twin turbochargers sourced from Hitachi. Two trim packages were offered;

11571-449: The inner housing provides sufficient accuracy for determining chamber volume. Different approaches have been used over time to evaluate the total displacement of a Wankel engine in relation to a reciprocating engine: considering only one, two, or all three chambers. Part of this dispute was because of Europe vehicle taxation being dependent on engine displacement, as reported by Karl Ludvigsen . If y {\displaystyle y}

11704-406: The installation of a rotary engine gave Japanese buyers a financial advantage when it came time to pay the annual road tax in that they bought a car that was more powerful than a traditional inline engine, but without having the penalty for having an engine in the higher above-one-litre tax bracket. The front suspension was a coil-sprung double-wishbone design with an anti-roll bar . The rear used

11837-536: The intake gas and the exhaust gas cannot be properly separated. The operating principle is similar to the Otto operating principle; the Diesel operating principle with its compression ignition cannot be used in a practical Wankel engine. Therefore, Wankel engines typically have a high-voltage spark ignition system. In a Wankel engine, one side of the triangular rotor completes the four-stage Otto cycle of intake, compression, expansion, and exhaust each revolution of

11970-466: The introduction of the short-lived Citroën GS Birotor , as well as any remaining NSU RO80 sedans. The Cosmo was Mazda's largest rotary-powered coupé, based on the LA series Mazda Luce floor pan and mechanics, but slightly heavier due to body design and more luxurious appointments, including a five-link rear suspension and rear disc brakes. It was available with the 12A and 13B engines. This series Cosmo

12103-414: The material suited for withstanding combustion heat stress. Among the alloys cited for Wankel housing use are A-132, Inconel 625, and 356 treated to T6 hardness. Several materials have been used for plating the housing working surface, Nikasil being one. Citroën, Daimler-Benz, Ford, A P Grazen, and others applied for patents in this field. For the apex seals, the choice of materials has evolved along with

12236-430: The number of shaft revolutions needed to complete a cycle ( N / n c {\displaystyle N/n_{c}} is the frequency of the thermodynamic cycle), then the total power output is: Kenichi Yamamoto and Walter G. Froede placed y = 1 {\displaystyle y=1} and n c = 1 {\displaystyle n_{c}=1} : With these values,

12369-561: The obligation affordable to most buyers, while having more power than traditional piston engines of the same official displacement. The third generation HB Cosmo from 1981 shared the Mazda HB chassis with its twin, the Mazda Luce . Some versions of both HB cars were sold overseas as the Mazda 929. The HB Cosmo was offered as a coupé (also called two door hardtop), as a sleek frameless window sedan (also called four door hardtop), and as

12502-488: The oil flow inside the engine, and the engine cooling. The first fully functioning KKM engine, the KKM 125, weighing in at only 17 kg (37.5 lb) displaced 125 cm and produced 26 PS (19 kW) at 11,000   rpm. Its first run was on 1 July 1958. In 1963, NSU produced the first series-production Wankel engine for a car, the KKM 502 (see Figure 6.). It was used in the NSU Spider sports car, of which about 2,000 were made. Despite its "teething troubles",

12635-664: The original Cosmo. The engine of the MX-5 was replaced by an early version of the Renesis rotary engine , later found in the Mazda RX-8 . The Cosmo 21 was revealed around the same time as many other retro style cars, including the Volkswagen New Beetle and the New Mini , adding to the growing list of retro style cars being produced in this era. Rumours of the Cosmo 21 entering limited production circulated in Japan, but

12768-506: The other hand, the same ignition timing of L and T leads to a higher energy conversion. Hydrocarbons adhering to the combustion chamber wall are expelled into the exhaust at the peripheral outlet. Mazda used 3 spark plugs in their R26B engine per chamber. The third spark plug ignites the mixture in the trailing side before the squish is generated, causing the mixture to burn completely and, also speeding up flame propagation, which improves fuel consumption. According to Curtiss-Wright research,

12901-430: The performance of Wankel engines. Side intake ports (as used in Mazda's Renesis engine) were first proposed by Hanns-Dieter Paschke in the late 1950s. Paschke predicted that precisely calculated intake ports and intake manifolds could make a side port engine as powerful as a PP engine. As formerly described, the Wankel engine is affected by unequal thermal expansion due to the four cycles taking place in fixed places of

13034-402: The problem of correctly representing their displacement for the purposes of competition arose. Rather than force participants who drove vehicles with piston engines, who were the majority, to halve their quoted displacement, most racing organizations decided to double the quoted displacement of Wankel engines. The key for comparing the displacement between the 4-cycle engine and the rotary engine

13167-463: The problem. Wankel engines have a problem not found in reciprocating piston four-stroke engines in that the block housing has intake, compression, combustion, and exhaust occurring at fixed locations around the housing. This causes a very uneven thermal load on the rotor housing. In contrast, four-stroke reciprocating engines perform these four strokes in one chamber, so that extremes of "freezing" intake and "flaming" exhaust are averaged and shielded by

13300-421: The problems that made prior attempts to perfect the rotary engines fail, by developing a configuration with vane seals having a tip radius equal to the amount of "oversize" of the rotor housing form, relative to the theoretical epitrochoid, to minimize radial apex seal motion plus introducing a cylindrical gas-loaded apex pin which abutted all sealing elements to seal around the three planes at each rotor apex. In

13433-577: The race in fourth overall. This was to be the only racing outing for the Cosmo—the next Mazda race car would be a Familia Rotary (R100) . The Series I/L10A Cosmo was powered by a 0810 two-rotor engine with 982 cc of displacement and produced about 110 hp (thus the 110S name used in export markets). It used a Hitachi four-barrel carburetor and an odd ignition design—two spark plugs per chamber with dual distributors. A four-speed manual transmission and 14-inch wheels were standard. In Japan,

13566-472: The rotary engine as forward-thinking, with a focus on future developments and technology. The first Mazda to bear the Cosmo name (called the 110S on models intended for export) was (along with the NSU Ro80 ) one of the first production cars to feature a 2-rotor Wankel engine . A prototype was presented at the 1964 Tokyo Motor Show , one month before the 1964 Summer Olympics , and after the introduction of

13699-429: The rotor (equivalent to three shaft revolutions, see Figure 8.). The shape of the rotor between the fixed apexes is to minimize the volume of the geometric combustion chamber and maximize the compression ratio , respectively. As the rotor has three sides, this gives three power pulses per revolution of the rotor. Wankel engines have a much lower degree of irregularity relative to a reciprocating piston engine, making

13832-410: The rotor housing and determined by the generating radius R {\displaystyle R} , the rotor width B {\displaystyle B} , and the parallel transfers of the rotor and the inner housing a {\displaystyle a} . Since the rotor has a trochoid ("triangular") shape, the sine of 60 degrees describes the interval at which the rotors get closest to

13965-443: The rotor housing. Therefore, The rotor path s {\displaystyle s} may be integrated via the eccentricity e {\displaystyle e} as follows: Therefore, For convenience, a {\displaystyle a} may be omitted because it is difficult to determine and small: A different approach to this is introducing a ′ {\displaystyle a'} as

14098-407: The same. The Wankel engine has a significantly higher (Δt K >100 K) exhaust gas temperature than an Otto engine, especially under low and medium load conditions. This is because of the higher combustion frequency and slower combustion. Exhaust gas temperatures can exceed 1300 K under high load at engine speeds of 6000 rpm . To improve the exhaust gas behavior of the Wankel engine,

14231-479: The series name reflects this value ("10" suggesting 1.0 litres). These engines featured the mainstream rotor dimensions with a 60 mm (2.4 in) depth. The rotor housing was made of sand-cast aluminium plated with chrome, while the aluminium sides were sprayed with molten carbon steel for strength. Cast iron was used for the rotors themselves, and their eccentric shafts were of expensive chrome-molybdenum steel. The addition of aluminium/carbon apex seals addressed

14364-413: The series name reflects this value ("13" suggesting 1.3 litres). This was the only production Mazda Wankel with different rotor dimensions: Radius was 120 mm (4.7 in) and offset was 17.5 mm (0.69 in), but depth remained the same as the 10A at 60 mm (2.4 in). Another major difference from the previous engines was the integrated water-cooled oil cooler. The 13A was used only in

14497-406: The shaft in a hula-hoop fashion. The Wankel is a 2:3 type of rotary engine, i.e., its housing's inner side resembles a two lobes oval-like epitrochoid (equivalent to a peritrochoid),. In contrast, its rotary piston has a three vertices trochoid shape (similar to a Reuleaux triangle ). Thus, the Wankel engine's rotor constantly forms three moving working chambers. The Wankel engine's basic geometry

14630-470: The show The Return of Ultraman . Cosmos were built in five batches: In 1968, Mazda went racing with the Cosmo. They selected one of the most grueling tests in Europe to prove the reliability of the rotary engine, the 84-hour Marathon de la Route at the legendary Nürburgring circuit in Germany. Two mostly stock Cosmos were entered, along with 58 other cars. One major change to the cars' 10A engines

14763-422: The succeeding decades as the production of road-going vehicles progressed. The advantages of compact design, smoothness, lower weight, and fewer parts over the reciprocating piston internal combustion engines make the Wankel engine suited for applications such as chainsaws , auxiliary power units (APUs), loitering munitions , aircraft , jet skis , snowmobiles , and range extenders in cars . The Wankel engine

14896-618: The triple rotor 20B-REW version a rarer car. Although the Cosmo remained a Japanese market-only vehicle (export had been proposed originally under the Eunos sales channel, and under the stillborn Amati brand in the USA), used Cosmos have found their way to various RHD countries thanks to import regulations for private importers from these countries. The Cosmo appears in Sega GT and in the Gran Turismo and Gran Turismo 2 games, as well as

15029-429: The two-rotor design; with the depth increase each chamber displaced 573 cc (35.0 cu in) so two chambers (one per rotor) would displace 1,146 cc (69.9 cu in); the series name continues earlier practice and reflects this value ("12" suggesting 1.2 litres). The 12A series was produced for 15 years, from May 1970 through 1985. In 1974, a 12A became the first engine built outside of western Europe or

15162-512: The uneven thermal distribution within the housings causing distortion and loss of sealing and compression. This thermal distortion also caused uneven wear between the apex seal and the rotor housing, evident on higher mileage engines. The problem was exacerbated when the engine was stressed before reaching operating temperature . However, Mazda Wankel engines solved these initial problems. Current engines have nearly 100 seal-related parts. The problem of clearance for hot rotor apexes passing between

15295-563: Was addressed with heat-resistant rubber oil seals at the sides of the rotors. This early engine had a rotor radius of 90 mm (3.5 in), an offset of 14 mm (0.55 in), and a depth of 59 mm (2.3 in). The very first Mazda Cosmo prototype used a 798 cc (48.7 cu in) L8A two-rotor Wankel. The engine and car were both shown at the 1963 Tokyo Motor Show . Hollow cast iron apex seals reduced vibration by changing their resonance frequency and thus eliminated chatter marks. It used dry-sump lubrication . Rotor radius

15428-475: Was ahead of its time electronically as well by being offered with Car Communication System , a CRT colour touch-screen controlling climate control , mobile phone , GPS car navigation, NTSC TV , radio and CD player. The instrumentation used a LCD display rendering analog gauges with indicator needles that "floated" and using vivid colors for various functions. The Cosmo was speed limited to 180 km/h (111.8 mph) to suit Japanese regulations, but

15561-579: Was also used to power motorcycles and racing cars . The Wankel engine is a type of rotary piston engine and exists in two primary forms, the Drehkolbenmotor (DKM, "rotary piston engine"), designed by Felix Wankel (see Figure 2.) and the Kreiskolbenmotor (KKM, "circuitous piston engine"), designed by Hanns-Dieter Paschke (see Figure 3.), of which only the latter has left the prototype stage. Thus, all production Wankel engines are of

15694-401: Was believed to be the only remaining Series II Cosmo in the United States, though the original Cosmo 10A engine has been replaced with a 12A from an RX-7. However, Mazda's U.S. division "found another in the garage of Phoenix-area car collector Glenn Roberts and made an offer that he couldn't refuse," according to Car and Driver magazine's September 2007 issue ("A Tale of Two Rotaries"). There

15827-454: Was continually used in Japan from 1972's Mazda Luce / RX-4 through 2002's RX-7. The 13B was designed with both high performance and low emissions in mind. Early vehicles using this engine used the AP name. Applications: A tuned intake manifold was used in a Wankel engine for the first time with the 13B-RESI . RESI = Rotary Engine Super Injection. The so-called Dynamic Effect Intake featured

15960-456: Was identified as the main cause. Mazda then used aluminum-impregnated carbon apex seals in their early production engines. NSU used carbon antimony-impregnated apex seals against chrome. NSU developed ELNISIL coating to production maturity and returned to a metal sealing strip for the RO80. Mazda continued to use chrome, but provided the aluminum housing with a steel jacket, which was then coated with

16093-547: Was joined by the short-lived Mazda Roadpacer , a large, heavy sedan powered only by a rotary engine. While the powerful rotaries received most of the attention, with the 13B-engined version with a manual transmission being able to reach a top speed of 195 km/h (121 mph), a piston-engined version was also on offer at the bottom of the range. The Cosmo 1800 , used a 1769 cc (80 x 88 mm) inline-four SOHC engine that produces 100 PS (73.5 kW) and 110 lb⋅ft (149 N⋅m). After Mazda noted

16226-635: Was known as the Cosmo AP (Anti-Pollution) in Japan, and sold internationally as the Mazda RX-5 , though in some export markets its piston-powered counterpart was called the Mazda 121 (a name later applied to Mazda's subcompact model). The anti-pollution label reflected that the cars were able to meet the strict, 1976 Japanese emissions standards, thanks to the installation of a thermal reactor which kept hydrocarbon levels down. The CD Cosmo/RX-5 series

16359-628: Was never placed into production. It was a slimmed down derivative of the 10A engine as fitted to the R100. A prototype engine is on display at the Mazda Museum in Hiroshima , Japan. The 13A was designed especially for front-wheel drive applications. It was a two-rotor design, with each chamber displacing 655 cc (40.0 cu in) so two chambers (one per rotor) would displace 1,310 cc (80 cu in); continuing earlier practice,

16492-430: Was now coated with a new process: The new Transplant Coating Process (TCP) featured sprayed-on steel which is then coated with chrome. Gross output was 105 hp (78 kW) at 7000 rpm and 135 N⋅m (100 lbf⋅ft) at 3500 rpm. Applications: Mazda began development on a single rotor engine displacing 360 cc (22 cu in), and was designed for kei car use in the upcoming Mazda Chantez but

16625-532: Was officially the fastest production car in Japan until being overtaken by the FJ20ET -powered R30 Skyline RS . The rotary engine had financial advantages to Japanese consumers in that the engine displacement remained below 1.5 litres, a significant determination when paying the Japanese annual road tax which kept the obligation affordable to most buyers, while having more power than the traditional inline engines. The HB Cosmo and Luce names were used in Japan, with

16758-511: Was positioned as a personal luxury car , with a focus on comfort and high equipment levels rather than outright sportiness. When introduced, it had a fastback bodystyle with three side windows; the one just behind the B-pillar could be wound down. Inspired by the US market, in particular the 1970s era Lincoln Continental , a notchback coupé model called the Landau appeared in early 1977. Called

16891-413: Was quietly introduced for the 1974 Mazda RX-2 and RX-3. It had increased reliability from the previous series and also used a single distributor for the first time: the earlier 12A and 10A were both twin distributor engines. Applications: The 13B is the most widely produced rotary engine. It was the basis for all future Mazda Wankel engines, and was produced for over 30 years. The 13B has no relation to

17024-499: Was the 40A , a single-rotor engine very much like the NSU KKM400. Although never produced in volume, the 40A was a valuable testbed for Mazda engineers, and quickly demonstrated two serious challenges to the feasibility of the design: "chatter marks" in the housing, and heavy oil consumption. The chatter marks, nicknamed "devil's fingernails", were caused by the tip-seal vibrating at its natural frequency. The oil consumption problem

17157-415: Was the addition of a novel side- and peripheral-port intake system: A butterfly valve switched from the side to the peripheral port as RPM increased. The engines were limited to 130 PS (96 kW) to improve durability. The cars ran together in fourth and fifth place for most of the race, but the all-Japanese car was retired with axle damage in the 82nd hour. The other car, driven by Belgians, completed

17290-573: Was the predominant type available in the first years of the Wankel engine's development. Lead is a solid lubricant, and leaded petrol is designed to reduce the wearing of seals and housings. The first engines had the oil supply calculated with consideration of petrol's lubricating qualities. As leaded petrol was being phased out, Wankel engines needed an increased mix of oil in the petrol to provide lubrication to critical engine parts. An SAE paper by David Garside extensively described Norton's choices of materials and cooling fins. Early engine designs had

17423-486: Was up from the 40A to 98 mm (3.9 in), but depth dropped to 56 mm (2.2 in). One-, three-, and four-rotor derivatives of the L8A were also created for experimentation. The 10A series was Mazda's first production Wankel, appearing in 1965. It was a two-rotor design, with each chamber displacing 491 cc (30.0 cu in) so two chambers (one per rotor) would displace 982 cc (59.9 cu in);

17556-461: Was used to eliminate knocking , and later models featured a specially-designed smaller and lighter "Impact Turbo" which was tweaked for the unique exhaust signature of the Wankel engine for a 5-horsepower increase. The engine continued until 1989 in the HB Cosmo series but by that stage it had grown a reputation as a thirsty engine. Applications: The 12B was an improved version of the 12A and

17689-426: Was used under low loads for added fuel economy. A single peripheral exhaust port routed hot gas through the coolest parts of the housing, and engine coolant flowed axially rather than the radial flow used by NSU. A bit of oil was mixed with the intake charge for lubrication. The 0810 was modified for the racing Cosmos used at Nürburgring . These engines had both side- and peripheral-located intake ports switched with

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