A CNG conversion kit lets a petrol vehicle run on compressed natural gas while keeping its petrol system. It is not one part but a set of components that store the gas, bring its pressure down, meter it into the engine and tell the engine what is happening. Knowing what each part does makes it far easier to compare kits and to ask the right questions before a conversion.
The main components
Every bi-fuel CNG system is built from the same functional blocks, whatever the brand:
- Cylinder: stores natural gas at high pressure. Its capacity sets how far the vehicle travels between fills and how much boot space is used.
- Cylinder valve and filling valve: control gas leaving the cylinder and let it be refuelled at a station.
- High-pressure gas line: carries gas from the cylinder to the front of the vehicle.
- Reducer (pressure regulator): brings the gas down from storage pressure to a pressure the engine can use.
- Injectors or mixer: deliver the gas into the engine’s intake.
- Electronic control unit (ECU) and wiring: decides how much gas to inject and when, based on signals from the engine.
- Fuel selector switch: lets the driver switch between CNG and petrol.
Mixer systems and sequential injection
Early conversion kits used a mixer: gas was drawn into the air intake in a way loosely comparable to a carburettor. These systems are simple but have little ability to adapt to modern engine management.
Sequential injection systems are designed for fuel-injected engines. Each cylinder gets its own gas injector, timed by the kit’s ECU from the same signals the petrol injectors use. Because gas delivery follows the engine’s own control strategy, sequential systems are the usual choice for modern multi-point fuel-injected petrol cars. V6 Autotech supplies sequential CNG kits of this kind.
Why the whole system matters, not one part
A kit performs only as well as its weakest link. A good reducer paired with poorly sized injectors, or a correct kit installed without proper calibration, can still run badly. That is why kit selection, installation and calibration are treated as one job. See how the conversion process works.
Standards that apply in India
In India, CNG vehicles and CNG kit components, including their installation, are covered by the automotive industry standards AIS-024 and AIS-028, published by ARAI on behalf of the Automotive Industry Standards Committee. The Central Motor Vehicles Rules refer to these standards for CNG vehicles and kits. In practice, this means a conversion should use a kit approved for the vehicle and be carried out by an installer who can provide the matching documentation.
Rules and their revisions change over time, so confirm the current position with your RTO or installer before converting.
