Developing an Engine with a Prechamber

The first Civic/CVCC vehicle (December 1973)

The process of trial and error continued, leading Date to conclude that it would be difficult to catch up with the competition in Japan and America. After all, if Honda were simply to conduct the same type of research as others are doing, there would be no competitive edge. Date decided that Honda should take another route. He conferred with Yagi and Nakagawa about the possibility of creating lean combustion via a prechamber. He knew this was a feature not used in conventional engine designs.

True, some diesel units had prechambers, and research was being conducted in the Soviet Union to achieve a similar process using a gasoline engine in order to use low grade fuel or to improve fuel economy. Since no research was being conducted for the purpose of controlling air pollution, it was decided that the pursuit would be worthwhile. Accordingly, the research on prechambers began, with the N600 engine as the basis for modification. Otani and Akira Okubo, who were in charge of design, did not have a minute to spare. They could count on regular appearances from Mr. Honda, popping in with instructions as he studied the plan.

“Just when we were about to give our plan its finishing touches,” recalled Otani, “Mr. Honda would give us new instructions. It always meant we’d have to redo it all from scratch.” Soichiro Honda had no patience for the long wait required to see completion of the trial engine manufacture. “We have engines with prechambers among our general-purpose engines, don’t we?” he said. “Why can’t you conduct research using those until the trial engine is completed?” With that, a series of tests began using the GD90 general-purpose disel engine.

The GD90 was a 2-cylinder, V-type 479 cc diesel unit with a prechamber; the ideal engine for their experiments. First, the researchers installed a sparkplug and gasoline-injection nozzle in the prechamber, remodeling the engine to allow the pressure ratio to be adjusted between 8:1 and 16:1. Tests using the converted GD90 were then conducted from December 1969 to February 1970, and the results seemed to indicate the possibility of a gasoline engine having lean combustion.

A trial-manufactured version of the single-cylinder, 300 cc N600 engine was completed in January 1970, allowing for the start of testing. It was the team’s goal here to determine the optimal conditions for a prechamber, so that lean combustion could be achieved. During their research Mr. Honda suggested, “Why not use the mechanical fuel-injection system we developed the other day?” (That system was introduced in October 1970.) It seemed to make sense, and with that the appropriate research was conducted using two fuel-supply methods: fuel injection and carburetion.

Subsequent to that, the team took up research on water-cooled engines, all the while keeping in mind the goal of emissions control.

However, Honda lacked water-cooled automotive engines that could be used for testing. Therefore, since they needed to proceed right away, tests were conducted using Nissan 1600 cc engines and other units. These tests unexpectedly produced a welcome byproduct: By using competitors” engines, their data would offer a more general application.
<< previous 4 of 8 next >>

<< The 1970 U.S. Clean Air Act Photo >>
<< Launch of the AP Lab
<< Achieving Lean Combustion through Trial and Error
<< Developing an Engine with a Prechamber
<< The Official Name: CVCC
<< The CVCC Engine System: An Immediate Success
<< Civic/CVCC Fuel Economy Draws Praise in the U.S.
<< The CVCC: Expressing the Honda Philosophy

Page Top

Honda Worldwide site

Home | Site Map | Site Index | About this Site

Copyright, Honda Motor Co., Ltd. and its subsidiaries and affiliates. All Rights Reserved.