The Oval Piston Engine / 1979

The Challenge of Engineering: To Find the Very Best Technology

The Oval Piston Engine / 1979

A 4-stroke Engine: The Natural Choice for a Comeback

Honda returned to the 500 cc class of the World Motorcycle Grand Prix series in 1979, following a twelve-year hiatus. The machine they had developed for their comeback - an entry in the World Grand Prix's most prominent class - was the NR500, powered by a four-stroke, DOHC V-four engine. With its oval piston engine incorporating eight valves and two connecting rods per cylinder, plus an aluminum semi-monococque frame complete with an inverted front fork, the machine surprised everyone with its daringly innovative technologies.

A 4-stroke Engine: The Natural Choice for a Comeback

The oval piston engine (0X engine, developed in 1979) was a product of Honda's drive to conquer technical challenges.

"When I look back at it, I'm not sure if we were experimenting with cutting-edge technologies or obsessed with foolish ideas," recalled Toshimitsu Yoshimura, an engineer involved in the development of the NR500's oval piston engine.

"At least we were doing something that was beyond the realm of conventional thinking. I'm not just talking about us, who were designing the engine, but also those who were creating the body.

"The emphasis was to create a difference-not just any difference but the difference that would work to our definite advantage. That's why we decided that Honda should go with four-stroke engines. We wanted to achieve our target through innovative technology, and in so doing have the edge over our competition."

Road-racing circuits were in those days dominated by bikes with two-stroke engines. Despite this trend Honda went with its NR500 machines equipped with a four-stroke engine. That decision, however, wasn't so much a bold move as it was a natural choice.

During its first years in motorcycle racing - dating back to a memorable entry in the Isle of Man TT Race - Honda won event after event with four-cycle engines. They achieved so much success, in fact, that four-cycle engines came to be thought of as a Honda specialty. Though two-stroke engines had the benefit of relatively higher output, nobody could stop Honda from wanting to develop four-stroke engines capable of producing even greater power. In that regard, the conventional thinking proved somewhat contrary at Honda. In fact, competing in the TT race was in every perspective an extraordinary decision.

Adding to the Honda preoccupation with four-stroke engines was the fact that many in top management, who had decided to make a comeback in the World Grand Prix series, and those involved in the development, were imbued with the philosophies of Soichiro Honda, who had criticized two-stroke engines as being little more than "bamboo tubes." To them, it was simply out of the question to reclaim their victory with anything less than a four-cycle engine.

Yoshimura, who had actually designed the engine, was from the very beginning a staunch advocate of the four-cycle approach. "Four-stroke engines," he said, "have distinctive mechanical processes. The (intake) valve closes tight, combustion occurs, the exhaust valve opens, and the exhaust is released. It's a sequence of independent processes, each with a different function, working together to facilitate the engine's entire operation. This is really fascinating, from an engineering standpoint. I believe this mechanism will be the basis of further advancement in engine technology."

Afterall there is no point in participating in a race if one isn't confident of victory. However, that confidence must come from hard work and the determination to stay the course through thick and thin. No matter how difficult the journey, one must continue as long as there is the slightest possibility of a positive outcome. It is in this very struggle that the value of one's endeavor exists. Honda engineers recognized how difficult the process could be, but ultimately they also knew success would be gratifying. Thus, the development team's decision to return to glory with four-stroke engines was most appropriate.

The Challenging Spirit of Honda

1990 - 1999
  1. The Birth of Twin Ring Motegi / 1997The Birth of Twin Ring Motegi / 1997
  2. Entry to Champ Car Racing / 1994Entry to Champ Car Racing / 1994
  3. Odyssey / 1994Odyssey / 1994
  4. Establishment of Honda Taiyo, Kibo-no-Sato Honda and Honda R&D Taiyo / 1992Establishment of Honda Taiyo, Kibo-no-Sato Honda and Honda R&D Taiyo / 1992
  5. Hosting Hosting "Orei-no-kai" / 1991
  6. The NSX / 1990The NSX / 1990
1980 - 1989
  1. The VTEC Engine / 1989The VTEC Engine / 1989
  2. Honda EV Plus: The Dream of an Electric Vehicle / 1988Honda EV Plus: The Dream of an Electric Vehicle / 1988
  3. An Automated Line for Painting and Coating / 1988An Automated Line for Painting and Coating / 1988
  4. Four-Wheel Steering System (4WS) / 1987Four-Wheel Steering System (4WS) / 1987
  5. The Airbag System / 1987The Airbag System / 1987
  6. The ZE Engine (GX110 / 140 / 240 / 270 / 340 Series) / 1983The ZE Engine (GX110 / 140 / 240 / 270 / 340 Series) / 1983
  7. Formula One Entry / 1983Formula One Entry / 1983
  8. Development of Honda's Franz System Car / 1982Development of Honda's Franz System Car / 1982
  9. The World's Smallest Welding Line / 1982The World's Smallest Welding Line / 1982
  10. Transfer Lines for Modular Components / 1981Transfer Lines for Modular Components / 1981
  11. The Car Navigation System / 1981The Car Navigation System / 1981
  12. City / 1981City / 1981
  13. The F200 The F200 "Komame" Mini-Tiller / 1980
  14. Establishing Honda of America Manufacturing / 1980Establishing Honda of America Manufacturing / 1980
1970 - 1979
  1. The Oval Piston Engine / 1979The Oval Piston Engine / 1979
  2. Returning to the World Motorcycle Grand Prix / 1979Returning to the World Motorcycle Grand Prix / 1979
  3. The HR21 Lawn Mower / 1978The HR21 Lawn Mower / 1978
  4. Creating Hometown Forests / 1977Creating Hometown Forests / 1977
  5. The ME Engine (G100 / 150 / 200 / 300 / 400 Series) / 1977The ME Engine (G100 / 150 / 200 / 300 / 400 Series) / 1977
  6. Introducing the Accord / 1976Introducing the Accord / 1976
  7. CG125 / 1975CG125 / 1975
  8. Establishment of Honda Engineering / 1974Establishment of Honda Engineering / 1974
  9. Company Leaders Honda and Fujisawa Retire; Kawashima Assumes Presidency / 1973Company Leaders Honda and Fujisawa Retire; Kawashima Assumes Presidency / 1973
  10. Announcing the Civic / 1972Announcing the Civic / 1972
  11. Introducing the CVCC / 1972Introducing the CVCC / 1972
  12. Holding All Honda Idea Contests / 1970Holding All Honda Idea Contests / 1970
  13. Launching the Office of Safe Driving Promotional Operations / 1970Launching the Office of Safe Driving Promotional Operations / 1970
1960 - 1969
  1. The Dream CB750 FOUR / 1969The Dream CB750 FOUR / 1969
  2. Launching the Honda 1300 / 1968Launching the Honda 1300 / 1968
  3. The Hondamatic Transmission / 1968The Hondamatic Transmission / 1968
  4. Entering the Auto Market at Last / 1966Entering the Auto Market at Last / 1966
  5. The E300 Portable Generator / 1965The E300 Portable Generator / 1965
  6. Formula One Entry / 1964Formula One Entry / 1964
  7. Kyoto: Celebrating the Company's 15th Anniversary / 1963Kyoto: Celebrating the Company's 15th Anniversary / 1963
  8. Establishing Belgium Honda / 1963Establishing Belgium Honda / 1963
  9. Launching the S360 and T360 / 1962Launching the S360 and T360 / 1962
  10. Employing the Employing the "My Record" Project and Expert Certification / 1960
  11. The R&D Center Goes Independent / 1960The R&D Center Goes Independent / 1960
1950 - 1959
  1. Establishing American Honda Motor Co. / 1959Establishing American Honda Motor Co. / 1959

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