The Challenge

At present, the majority of passenger and small commercial vehicles sold in Australia and throughout the world run on petrol (gasoline) utilising multi point injection and sophisticated electronic controls. These are designed to maximise fuel economy and power output whilst minimising emissions. The advances in petrol technology have reduced the emissions advantage Autogas (Automotive LPG) had over petrol. Current gaseous fuel systems utilise carburettor type technology superseded in petrol engines by multi point injection systems more than 10 years ago and has the following challenges,

1. They have significantly slower and less accurate fuel metering than multi point injection. (This will inhibit the use of these systems when the next emission levels are introduced.)
2. They create conditions within the engine that can produce "backfires" in the air intake system causing costly engine damage.
3. They are incompatible with the OBD (On Board Diagnostics) systems within the OEM (Original Equipment Manufacturer) computer which impending emission standards will require to be fully effective on all fuels.
4. They are incompatible with features such as traction control, rev limiting, speed limiting and limp home provided by the OEM multipoint injection systems.

The System

The system comprises the three main components
plus wiring and electrical components

The Gas Injection Technologies Stealth Injection System is the leading edge multipoint sequential vapour fuel injection technology being developed in the world. It uses specially designed “stealth” injectors that are controlled directly by the motor vehicle’s original computer with no interface. It enables the system to take advantage of all the computer functionalities that are developed to optimise Emissions, Performance and Driveability that the motor vehicle manufacturers spend millions of dollars designing. This has many advantages especially as the complex on board diagnostic systems are introduced to meet the impending emission standards.

In the early days of development GTi tried to introduce a second computer to integrate with the OEM computer using a single point system. (Which is the current European injection technology being introduced) GTi discovered that because of the many ways OEM computers control the petrol injectors under different engine operating conditions it was a highly complex and expensive task to attempt to distinguish the OEM signal and rearrange the signal to suit a gas control mechanism. There are also on board diagnostics in the OEM computer to ensure correct petrol injector operation that are negatively affected when the original injectors are disabled. GTi made the fundamental decision that the most effective way to integrate with the OEM computer was to produce the stealth gas injectors that emulated petrol injector operation.

The end result is a very simple system with the three major components outlined above. In all our testing, GTi have confirmed that the closer we get to fully emulating the petrol components the gas injection takes over from, the better results in emissions, performance, functionality and compatibility with the ever advancing OEM computer and on board diagnostics.

GTi has looked at other successful Autogas technologies in carburettors and gauges. In both of these cases the success lay in the emulation of the original petrol technology. The GTi system uses the same petrol injection methodology but with highly specialised "stealth" gaseous injectors that are indistinguishable by the OEM computer.

All other vapour injection systems use a single point injection system with a simple distributor arrangement that require an additional computer to control the system and also appease the OEM on board diagnostics. There are liquid multipoint injection systems, these are highly expensive and still require a second computer.

Testing

Evidence for Success

The GTi system has been installed on over 14 vehicles including 6 taxis and has had over 700,000kms of testing. The testing GTi have conducted with a taxi fleet has been very encouraging with one of the systems lasting for 200,000km. We have successfully tested the latest injectors for over 300 million cycles, which will give a useable life in excess of 250,000km.

GTi have conducted 3 emission tests with the GTi system and have passed all tests on the different vehicles. One vehicle had 195,000km usage when tested. The graph below shows the emission levels required by ADR 37/01 and the emissions recorded on petrol and gas injection on the same vehicle.

This test was conducted on a production petrol vehicle that was then converted to use the GTi system. The test results show a 20% reduction in CO2 greenhouse gas emissions and a 50% reduction in regulated emissions compared to petrol. The regulated emissions were a 70% reduction from the ADR 37/01 limits. The 20% reduction in CO2 emissions will assist the Federal Government in the fight against greenhouse gas emissions.

Perception improvements with GTi system

Increased Power

A major negative perception of the public is the loss of engine performance on Autogas. This is due to the inadequate carburetion design of some current Autogas technologies and the vapour gas displacing approximately 7% of the oxygen in the inlet manifold. As the graph below illustrates the GTi system can actually INCREASE power over a standard petrol engine occurs because:

1. The GTi system injects the gas at the inlet valve which leaves the inlet manifold full of oxygen.
2. Late model engines have increased compression ratios. They also have highly accurate computers to improve emissions and engine performance that can change operating parameters in consideration of fuel quality. Because Autogas generally has a higher octane rating and better burning characteristics than unleaded fuels, the OEM computer can change the operating parameters, which result in the increased power. The paradigm shift in the public's perception of performance improvements on Autogas will play an important role in improving the public awareness of Autogas.

The paradigm shift in the public's perception of performance improvements on Autogas
will play an important role in improving the public awareness of Autogas

Exhaust Smells Minimised.

Before catalytic converters were installed, Autogas exhaust smelled due to the odorant in Autogas for detecting leaks, burning in the engine. Since the introduction of petrol fuel injection and exhaust catalytic converters the main reason for the obnoxious smells associated with Taxis on Autogas is because they are poorly serviced and have suffered backfire damage, resulting in overly rich fuel mixtures burning in the engine and catalytic converter. With the GTi system the OEM computer is controlling the fuel mixtures at factory levels and it doesn't suffer backfire damage. Also, because Autogas doesn't have the sulphur content of petrol, exhaust smells are reduced to levels below petrol.

Engine and Exhaust Life Improved

Because of the lack of sulphur and other harmful toxic emissions that are present in petrol, Autogas extends engine life due to the clean burning characteristics and exhaust system life is dramatically improved. Because the OEM computer controls the GTi system and the fuel mixtures are maintained to factory specifications, engine damage caused by incorrect fuel mixtures is reduced to a minimum. Since the introduction of unleaded fuel, correctly tuned Autogas has no negative effects on engine life.

Improved Fuel Consumption

Fuel consumption on Autogas is higher than petrol due Autogas having slightly less heat value per litre than petrol. Because current technology gas systems have very basic fuel management criterion compared to the advanced OEM computers, Autogas fuel consumption is increased approximately 27% over petrol operation. The GTi system utilises all the benefits obtained by the OEM engine management and results in a 10% - 15% improvement in fuel consumption compared to current Autogas technologies. This produces significant savings over the life of the vehicle.

Summary

Governments throughout the world are searching for ways to reduce the problems of air quality. One of the major ways to achieve benefits in air quality is to convert vehicles to cleaner burning gaseous fuels. The GTi Enviro-win system with stealth injector technology is a simple user-friendly system that works for the consumer and benefits the environment at an affordable price. The motor vehicle manufacturers are looking for a cost effective system that is easy to assimilate into the production process, provides improved emission outcomes and maintains engine management functions. The GTi system offers the following benefits.

• Emission reliability similar to petrol and dramatically better than current systems.
• Consumers can maintain functions like traction control etc.
• Affordable Cost
• Increased power over current systems and depending on the engine and engine management criterion sometimes over petrol.
• Improved fuel consumption over current systems.
• Catastrophic backfires eliminated.
• Engine damage reduced due to OEM fuel management criterion
• Engine driveability and functionality indistinguishable from petrol.
• Only software and minor hardware changes necessary for production purposes.
• Easily assimilated into the OEM production process

Petrol fuel management has developed from carburettors to single point fuel injection, multipoint fuel injection and finally sequential multipoint fuel injection. While other Autogas system manufacturers are making the transition from carburettors to single point injection. The GTi system brings Autogas straight into the same league as the latest and future complex OEM petrol injection systems. This will allow Autogas to have the latest Autogas injection technology to suit the high technology OEM systems and allows Autogas to maintain its emission advantage over petrol.