The ZE Engine (GX110 / 140 / 240 / 270 / 340 Series) / 1983

The Concept: An OHV + Inclined Cylinder that Changed the World of General Purpose Engines

The ZE Engine (GX110 / 140 / 240 / 270 / 340 Series) / 1983

Confidence in the Search for an Ideal Design

Two engines were developed under the ZE01 project heading - one with 3.5 horsepower and another with 5 horsepower - and each was to share parts with the other. Yamaguchi, now the project leader, wanted to reflect in the new engines everything he had learned from his own experience. He understood what the ME had failed to achieve, but he understood equally well the weakness of engines from other manufacturers. Further, he knew why the customers had not been satisfied. Therefore, he was confident the new OHV engines would solve the problems inherent in the previous models. He was willing to introduce various ideas, as long as they did not raise the cost, and in this task he applied himself through long hours at the drawing board.

Yamaguchi's initial challenge was engine size, since with a general purpose engine the fuel tank is normally found on top. However, with an SV engine the tank can be mounted directly to the body. Moreover, an OHV engine has its cylinder head and valves positioned between the body and tank, thus increasing the height of the engine assembly. Increased height means a higher center of gravity and more significant amounts of vibration. It also affects engine manageability when installed in a work machine. Detachment of the fuel tank requires an extra function in order to feed fuel to the engine. Thus, the tank should remain connected to the engine, ideally above the body. However, installation compatibility was the most important issue of all, and most companies were still loyal to SV engines. No matter how good the performance was, no OEM company would adopt an OHV engine if it meant a change in specifications. The Honda engine, which lacked installation compatibility, had already made that clear.

Yamaguchi solved this problem with the help of the ME engine. First, he drew an outline of an ME, then he tried to fit the OHV engine into it. After all, the ME's dimensions had been determined through intensive studies of installation compatibility. Thus, an OHV that could fit within the ME's dimensions would ensure installation compatibility. After drawing many designs with different cylinder positions, Yamaguchi finally came up with the idea of setting the cylinder at an incline.

The idea was not so convincing to other staff members, though. In fact, the ZE engine would not be the first Honda engine for which an inclined cylinder had been attempted. The G25 engine released in 1966 had adopted this design with a cylinder placed almost horizontally. However, that engine design was fraught with problems, including heat damage. The staff, who remembered the experience, was very skeptical. "We've already had enough anguish," they said. "Why the inclined cylinder now? What's wrong with the vertical layout?'

Yamaguchi was in fact involved with development of the G25 engine, so he knew well the struggles it had produced. "There was no meaning in developing OHV engines that couldn't promise installation compatibility," Yamaguchi recalled. "If the ideal design for a general purpose engine means an inclined cylinder, we must face the obstacles and overcome them. We had already had the facts of engineering. We couldn't afford to hesitate, now. We had to make the best use of that experience."

A series of long discussions took place, and through Yamaguchi's articulate passion, a consensus was finally found. Following the decision, the staff members visited farms in mountain areas in order to study how cultivators and other machines were used on the slopes and apply that data to laboratory tests. Consequently, the angle was set to 25 degrees to prevent the backflow of oil. With that, the inclined cylinder's specifications were at last determined.

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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