History of Honda’s PGM-FI development for motorcycles

Honda started more than 20 years ago to develope a FI system to constantly provide the optimum air fuel ratio required by the engine using electronic control techniques. Since then, Honda has been actively promoting the application of FI to motorcycles as a technique to realize environmental performance and high level driveability.

In 1982, Honda marketed the first-in-the-world, fuel injected motorcycle CX500TURBO, which attained both better acceleration performance than the CB900F and better fuel economy than the base model CX500. In 1998, the environmentally friendly sport tourer model VFR800FI was marketed. This model, using the PGM-FI and the newly developed three-way catalyst, attains 1/30 CO emissions and 1/10 HC+NOx emissions from the EURO1, which is the European exhaust emission regulation enacted in 1999. And now, the racing machine “RC211V” has been dominating the MotoGP races. The “RC211V” uses the PGM-FI, which aids in allowing the overwhelming power output of the RC211V to be controlled for efficient use by the rider. Honda always keeps improving the fuel injection system at the highest level of technical competition.

The first motorcycle equipped with an electronic fuel injection – CX500TURBO

In the late 1970’s, Honda R&D was filled with enthusiasm towards attaining “core technologies that would lead to the development of new technologies in the 1980’s”. Through discussions on what should be the core technologies, “turbo charging” was choosen, and the CX500 was selected as the base model. Honda defined the purpose of “turbo charging” not merely as a boost of extra power output from a large displacement engine, but an increase of specific power from a small displacement engine, and an increase in thermal efficiency by reducing the frictional losses per output. Simply stated, it was to attain both an increase in power output and a reduction in energy loss. Most critical in the development were the turbo charger and the fuel injection control systems. The CX500TURBO eventually made the first step of innovation into the 1980’s with its acceleration performance better than the “CB900F” and fuel economy better than the base model “CX500”.

Computer controlled fuel injection

One of the features of the CX500TURBO was the practical application of the computer controlled fuel injection system. Instead of using the then-conventional air flow meter, the computer-controlled fuel injection system calculated the injection volume using the two control maps, i.e., one for the boost zone where the basic injection volume was determined by the engine revolutions and the boost pressure, and the other for the throttle zone where the basic injection volume was determined by the engine revolutions and the throttle opening. The actual injection volume was adjusted by the intake density compensation, the intake air pressure and/or intake air temperatures, the supplement for acceleration, warming up, starting, the compensation for battery voltage, etc. Also incorporated in the computer-controlled fuel injection system was a self-diagnosis system that activated the warning lamp and the backup system to keep the engine running when a failure occurred in the system.

The racing machine of the 21st century – RC211V

In the world of championship motorcycle road racing, the machine regulations of the pinnacle 500cc class underwent a drastic reform, and changed its name to “MotoGP” in 2002. The machine regulations changed from a 2-stroke, 500cc engine to a 4-stroke, 990cc maximum displacement, and the name of the class was modified to “MotoGP”. The Honda RC211V is the machine that was developed to meet the new regulations. Honda has developed a unique engine having the V-5 configuration. After dominating the races in the debut year 2002, the RC211V keeps winning in an overwhelming manner in 2003.

FI control ensuring superb driveability

The MotoGP machine uses fully closed or partially opened throttle conditions way more frequently than the Formula 1 race cars, for example. Compared to the Formula one cars which use fully opened throttle frequently, the controllability of the power output is more critical than the maximum power output. Honda developed and applied new techniques to provide superb driveability for the PGM-FI used in the RC211V.

Twin injector

Providing the deflecting multi-hole levigation injectors before and after the throttle valve, and having each one take care of the low load zone (after throttle) and the high load zone (before throttle), both the driveability and the high power output have been realized.

Variable fuel pressure control

The accurate control of fuel supply and throttle controllability are attained by the ECU continuously controlling the fuel pressure. Predictive control of residual injected fuel When the throttle is opened or closed (fully opened, fully closed, not when kept at a partial opening), the “amount of fuel sticking” on the inlet port walls and flowing into the combustion chamber during the following combustion cycle is predicted and applied to the control to ensure the most suitable air fuel ratio for improvement in driveability and fuel economy.

List of Honda motorcycles equipped with a PGM-FI

The PGM-FI is one of the core technologies to attain the goals of clean exhaust gas and fuel economy. An inevitable next goal is to extend the application of the innovative technique to models in various categories that respond to a larger number of users. Through the newly developed compact PGM-FI, Honda increases the application from large touring models, to the super sport models, and the models targeted towards a larger number of people.