Natural-Gas Motronic

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Natural-Gas Motronic for sustainable mobility

Natural gas is a fossile fuel with a future. It is produced without the need for extensive refining, and its combustion places far less load on the environment than gasoline or diesel. For the special requirements of natural-gas engines Bosch has developed special technologies for gas injection and engine management.

The Bi-fuel System can change from gas to gasoline operation during driving without a torque jump


A fuel with many advantages

There is great potential for Compressed Natural Gas (CNG) due to it having very low emissions. Compared to gasoline, CNG combustion produces about 25% less carbon dioxide (CO2). Furthermore, CNG has a great potential for reducing untreated emissions. The exhaust gas is odorless and contains no particles.

CNG also has an advantage when being prepared as a fuel: it needs no additives and its production does without complicated refining processes. Another advantage is that CNG vehicles place no load on the world's scanty petroleum resources. Methane, CNG's major component, can also be produced from organic substances. This closes the CO2 cycle and long-term availability is increased even further.



CNG vehicles have proven themselves for years now. Since CNG filling stations are still few and far between, the vehicles are mostly equipped with bi-fuel systems, and the engine can run on either natural gas or gasoline.



CNG has a very high knock resistance (130 ROZ as opposed to between 91 and 100 ROZ for gasoline). This represents further potential for optimization of the CNG engine. This is ideally suited for supercharging, allowing downsizing concepts to be applied with the accompanying improvements in efficiency.

A fuel with many advantages

There is great potential for Compressed Natural Gas (CNG) due to it having very low emissions. Compared to gasoline, CNG combustion produces about 25% less carbon dioxide (CO2). Furthermore, CNG has a great potential for reducing untreated emissions. The exhaust gas is odorless and contains no particles.

CNG also has an advantage when being prepared as a fuel: it needs no additives and its production does without complicated refining processes. Another advantage is that CNG vehicles place no load on the world's scanty petroleum resources. Methane, CNG's major component, can also be produced from organic substances. This closes the CO2 cycle and long-term availability is increased even further.



CNG vehicles have proven themselves for years now. Since CNG filling stations are still few and far between, the vehicles are mostly equipped with bi-fuel systems, and the engine can run on either natural gas or gasoline.



CNG has a very high knock resistance (130 ROZ as opposed to between 91 and 100 ROZ for gasoline). This represents further potential for optimization of the CNG engine. This is ideally suited for supercharging, allowing downsizing concepts to be applied with the accompanying improvements in efficiency.

The Bi-fuel control unit NG Motronic


The bi-fuel NG-Motronic ECU

This ECU is based on the Motronic version for gasoline injection. It controls the CNG injectors via separate driver stages. The torque-guided control permits the simple integration of the functions which are specific for CNG operation. A number of advantages result from integrating both fuel systems in a bi-fuel ECU. For instance, lower wiring costs, and cost savings due to the second ECU becoming unnecessary. In addition, the system as a whole has considerable optimization potential.

A further advantage inherent in the single-ECU concept is the fact that at every operating point a coordinated change can be made between gasoline and CNG operation without any jump in torque.

The new Bosch natural gas injector valve


The NGI2 natural-gas injector

The first Bosch natural-gas injection valve came onto the market years ago. The new NGI2 injector was specifically developed for the demands of automotive CNG injection. It features a series of technical innovations and serves as a benchmark for gas metering. The components through which gas flows are designed to cope with the high gas volumes and the high throughflow velocity. Pressure losses before the throttling point and operating noise are kept to a minimum by a special flow guide.

The solenoid can be triggered by a standard driver stage, and its surface has been specially coated to prevent wear when used with oil-free gas.

With its special design, the NGI2 is far superior to all previously known gas-injection valves, and can be easily integrated in existing intake-manifold geometries.