General Motors Rotary Combustion Engine
Encyclopedia
The General Motors Rotary Combustion Engine (GMRCE) is an internal combustion Wankel engine
which uses a rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. In November 1970, GM paid $50 million for initial licenses to produce their version of the Wankel rotary engine, and GM
President Ed Cole
initially projected its release in three years. Chevrolet
, with impetus from Pete Estes
and John DeLorean, as well as Ed Cole worked on the Wankel. Bob Templin was the chief executive in charge of rotary-engine research at the GM Tech Center in Warren, Michigan
, but Ed Cole would leave his office in Detroit twice a week for the trip to Michigan taking charge of the program. The engine was initially targeted for an October 1973 introduction as a 1974 Chevrolet Vega
option.
Its mediocre fuel economy and the ill-timed Arab oil embargo
were contributing factors to end the GM rotary program.
magazine in the May 1972 article "GM Rotary Engine for the 1974 Vega", an illustration of the Wankel installed in a 1974 Vega hatchback showed a different grille, a lower, more sloped hood line, and a "GM Rotary" badge and Wankel crest on the rear quarter panel. They stated the Vega-rotary would be sold as a package with performance items, including mag-styled wheels, radial tires, and rally stripes.
The Wankel had so far proven more reliable than four, six, and eight-cylinder engines – GM-rotary engines were run up to 500000 miles (804,670 km) showing only minimal wear, and the engine's fewer moving parts assured its reliability. The final design General Motors Rotary Combustion Engine (GMRCE) was fixed when responsibility for the power plant's manufacture was turned over to General Motors Hydra Matic Division in August 1972 – two rotors displacing 206 cubic inches, twin distributors and coils, and a switch to aluminum housing construction. Iron couldn't match the heat-dissipating qualities of aluminum. In addition, there was also a rotor tip-seal problem in the cast-iron configuration, especially after 15,000 miles.RC2-206 Wankels were installed in 1973 Vegas for cold weather testing performed in Canada.
withstood.
In April 1973, the Environmental Protection Agency (EPA) relaxed emission standards for '75, and GM tuned the engine to provide better mileage at a sacrifice to exhaust emissions by reverting back to the earlier layout. Other refinements improved mileage to a remarkable 20 mpg, according to GM, but with the fuel breakthrough came related side-effect problems. Durability under the "hot" set-up began to deteriorate. Higher temperatures and pressures affected both apex seals and the chrome-on-steel-on-aluminum coating of the trochoid
surface. The surface plating tended to crack and flake away around the exhaust port, blamed by GM engineers on sudden cooling after hard, hot running.
Motor Trend
magazine, in the July 1973 article "The '75 Vega Rotary" quoted: "GM saw the rotary engine's future as probably much greater than they do today...mileage will be in the 16-18 mpg range. Compared to the normal piston (engine) Vega's 20 to 26 mpg, the whole rotary deal begins to look just a little less attractive, with what the price of gasoline skyrocketing, but that's another matter."
By November, 1973 the side-effect troubles were intense. No immediate solutions were being revealed by engineers working all but around the clock, their backs to the two walls of production tooling requirements and the need to freeze a design to begin emission certification. Ed Cole and his top engineer Frank Winchell, had taken personal charge of the project and had stopped work on all other GM-rotaries to focus on the problems of the Vega RC2-206 Wankel. A month later it was clear the Wankel would not be ready for either production or emissions certification in time for the start of the 1975 model year. A new model had now been planned to showcase the engine; The 1975 Vega-based Monza 2+2
.
On December 21, 1973 when GM paid another $10 million against its rotary licence fees, the company announced the first postponement.
Motor Trend in April 1974 predicted the outcome: "If the GM rotary engine hasn't made a place for itself in the company's lineup by fall, and if by then it hasn't been locked into the '75 model range - somewhere - the odds will increase that it may never go into production."
On September 24, 1974, Ed Cole postponed the Wankel engine, ostensibly due to emissions difficulties. He retired the same month. The rotary's emissions problem was mentioned with no specifics. GM admitted fuel economy for the rotary was sub-standard and postponed production in favor of further development. Pete Estes succeeded Ed Cole as GM President and never showed any special interest in the Wankel or in the perpetuation of Cole's ideas.General Motors' abandonment of the rotary engine affected American Motors. With an agreement to purchase power plants from General Motors, the 1975 AMC Pacer
was designed to utilize GM's new rotary engine, but AMC was forced to market the car with an inline six engine.
206 cubic inch Wankel vs. 307 cubic inch V8 engine
Wankel engine
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. Its four-stroke cycle takes place in a space between the inside of an oval-like epitrochoid-shaped housing and a rotor that...
which uses a rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. In November 1970, GM paid $50 million for initial licenses to produce their version of the Wankel rotary engine, and GM
General Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...
President Ed Cole
Ed Cole
Edward Nicholas Cole was an American automotive executive for General Motors.- Career :Cole was the son of a dairy farmer. In his youth, he designed, built, and sold homemade radio sets, and as a teenager became a field representative for a tractor manufacturer...
initially projected its release in three years. Chevrolet
Chevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
, with impetus from Pete Estes
Pete Estes
Elliot Marantette "Pete" Estes was an American automotive engineer and executive, most known as being the fifteenth president of General Motors, from 1974 to 1981...
and John DeLorean, as well as Ed Cole worked on the Wankel. Bob Templin was the chief executive in charge of rotary-engine research at the GM Tech Center in Warren, Michigan
Warren, Michigan
Warren is a city in Macomb County in the U.S. state of Michigan. The 2010 census places the city's population at 134,056, making Warren the largest city in Macomb County, the third largest city in Michigan, and Metro Detroit's largest suburb....
, but Ed Cole would leave his office in Detroit twice a week for the trip to Michigan taking charge of the program. The engine was initially targeted for an October 1973 introduction as a 1974 Chevrolet Vega
Chevrolet Vega
The Chevrolet Vega is a subcompact, two-door automobile that was produced by the Chevrolet division of General Motors for the 1971-1977 model years. Named after the star Vega, the car was powered by a lightweight aluminum-block inline four-cylinder engine...
option.
Its mediocre fuel economy and the ill-timed Arab oil embargo
Oil embargo
Oil embargo may refer to:*The 1967 Oil Embargo*The 1973 oil crisis*The 1979 energy crisis*The oil embargo placed on Japan by China, the United States, Britain, and the Dutch during the Sino-Japanese War, preceding World War II...
were contributing factors to end the GM rotary program.
History of Development
Popular SciencePopular Science
Popular Science is an American monthly magazine founded in 1872 carrying articles for the general reader on science and technology subjects. Popular Science has won over 58 awards, including the ASME awards for its journalistic excellence in both 2003 and 2004...
magazine in the May 1972 article "GM Rotary Engine for the 1974 Vega", an illustration of the Wankel installed in a 1974 Vega hatchback showed a different grille, a lower, more sloped hood line, and a "GM Rotary" badge and Wankel crest on the rear quarter panel. They stated the Vega-rotary would be sold as a package with performance items, including mag-styled wheels, radial tires, and rally stripes.
The Wankel had so far proven more reliable than four, six, and eight-cylinder engines – GM-rotary engines were run up to 500000 miles (804,670 km) showing only minimal wear, and the engine's fewer moving parts assured its reliability. The final design General Motors Rotary Combustion Engine (GMRCE) was fixed when responsibility for the power plant's manufacture was turned over to General Motors Hydra Matic Division in August 1972 – two rotors displacing 206 cubic inches, twin distributors and coils, and a switch to aluminum housing construction. Iron couldn't match the heat-dissipating qualities of aluminum. In addition, there was also a rotor tip-seal problem in the cast-iron configuration, especially after 15,000 miles.RC2-206 Wankels were installed in 1973 Vegas for cold weather testing performed in Canada.
Fuel economy vs reliability and meeting emissions
Early in 1973, progress on the generation I Wankel engine had progressed to the point where GM felt it had a good chance to meet '75 emissions standards. To meet those standards GM had to scrap the design theory of widely-spaced dual spark plugs and move them closer to the rotor chamber, Mazda fashion. That helped lower emissions but did not improve fuel economy, and GM was unwilling to face gas mileage criticism that MazdaMazda
is a Japanese automotive manufacturer based in Fuchū, Aki District, Hiroshima Prefecture, Japan.In 2007, Mazda produced almost 1.3 million vehicles for global sales...
withstood.
In April 1973, the Environmental Protection Agency (EPA) relaxed emission standards for '75, and GM tuned the engine to provide better mileage at a sacrifice to exhaust emissions by reverting back to the earlier layout. Other refinements improved mileage to a remarkable 20 mpg, according to GM, but with the fuel breakthrough came related side-effect problems. Durability under the "hot" set-up began to deteriorate. Higher temperatures and pressures affected both apex seals and the chrome-on-steel-on-aluminum coating of the trochoid
Trochoid
thumb|290px|right|A [[cycloid]] generated by a rolling circleTrochoid is the word created by Gilles de Roberval for the curve described by a fixed point as a circle rolls along a straight line...
surface. The surface plating tended to crack and flake away around the exhaust port, blamed by GM engineers on sudden cooling after hard, hot running.
Motor Trend
Motor Trend
Motor Trend is an American automobile magazine. It first appeared in September 1949, issued by Petersen Publishing Company in Los Angeles, and bearing the tag line "The Magazine for a Motoring World". Petersen Publishing was sold to British publisher EMAP in 1998, who sold the former Petersen...
magazine, in the July 1973 article "The '75 Vega Rotary" quoted: "GM saw the rotary engine's future as probably much greater than they do today...mileage will be in the 16-18 mpg range. Compared to the normal piston (engine) Vega's 20 to 26 mpg, the whole rotary deal begins to look just a little less attractive, with what the price of gasoline skyrocketing, but that's another matter."
By November, 1973 the side-effect troubles were intense. No immediate solutions were being revealed by engineers working all but around the clock, their backs to the two walls of production tooling requirements and the need to freeze a design to begin emission certification. Ed Cole and his top engineer Frank Winchell, had taken personal charge of the project and had stopped work on all other GM-rotaries to focus on the problems of the Vega RC2-206 Wankel. A month later it was clear the Wankel would not be ready for either production or emissions certification in time for the start of the 1975 model year. A new model had now been planned to showcase the engine; The 1975 Vega-based Monza 2+2
Chevrolet Monza
The Chevrolet Monza is a subcompact, four-passenger automobile produced by the Chevrolet division of General Motors for the 1975–1980 model years. The Monza is based on the Chevrolet Vega, sharing its wheelbase, width and 140 CID inline-4 engine...
.
On December 21, 1973 when GM paid another $10 million against its rotary licence fees, the company announced the first postponement.
Motor Trend in April 1974 predicted the outcome: "If the GM rotary engine hasn't made a place for itself in the company's lineup by fall, and if by then it hasn't been locked into the '75 model range - somewhere - the odds will increase that it may never go into production."
End of rotary program
AMC Pacer
The AMC Pacer is a two-door compact automobile produced in the United States by the American Motors Corporation between 1975 and 1980.Its initial design idea was started in 1971. The car's unusual rounded shape with massive glass area greatly contrasted with the three-box architecture with "square,...
was designed to utilize GM's new rotary engine, but AMC was forced to market the car with an inline six engine.
206 cubic inch Wankel vs. 307 cubic inch V8 engine
- Weight: Wankel - 255 lb (115.7 kg) / V8 - 465 lb (210.9 kg)
- Number of parts: Wankel - 698 / V8 - 1,103
- Moving parts: Wankel - 154 / V8 - 388
- Space requirement: Wankel - 5.5 cu ft (0.1557426585 m³) / V8 - 23 cu ft (0.651287481 m³)
- Net power @ rpm: Wankel - 150 hp @ 6,000 / V8 - 130 hp @ 4,000
- Net torque @ rpm: Wankel - 125 lbft @ 4,000 / V8 - 230 lbft @ 2,400
- Hp per lb.: Wankel - 0.59 / V8 - 0.28