Aftermarket CNG conversion costs, kits and
A guide to aftermarket CNG conversion types, costs, components and the installation process, based on information from industry installers.
Rising fuel prices are driving increased interest in aftermarket CNG conversions for cars. Autocar India, working with installers Blue Drive Traders and M.S Motors, details the technology, legalities, and costs involved.
CNG kit types and costs
Three main types of CNG conversion kits are available, with costs and compatibility varying significantly.
| Kit Type | Compatible Vehicles | Key Features | Approximate Cost (incl. installation & registration) |
|---|---|---|---|
| Venturi | BS3 and older cars | Uses a carburettor-like mixer; significant performance drop; being phased out. | Rs 30,000 - Rs 40,000 |
| Sequential | Modern naturally aspirated MPFI cars | Uses individual injectors and a dedicated ECU; nominal performance drop in daily use. | Rs 40,000 - Rs 75,000 (varies by car size & BS norms) |
| Direct-injection | Cars with direct petrol injection | Requires a mix of CNG and petrol (max 80:20 ratio); for turbocharged DI engines. | Rs 1 lakh - Rs 1.5 lakh |
Sequential kits for modern cars automate the switch from petrol to CNG based on engine temperature. Direct-injection kits are the newest and most expensive, offering lower efficiency gains due to the required petrol mix.
Components and installation process
A CNG kit's heaviest part is the steel tank, which can weigh nearly 70kg empty. Lighter composite or carbon fibre tanks cost two to three times more. The system includes a filling valve, high-pressure tubing, a pressure reducer, an injector rail, a MAP sensor, and a dedicated Electronic Control Unit (ECU). An optional Advancer can help mitigate power loss.
Professional installation takes four to five hours. The process begins with an engine health check. Mechanics then position components, install injectors into the intake manifold, wire in the CNG ECU, and complete the gas plumbing. A mounting frame is secured in the boot for the tank. After fitting the tank and routing the high-pressure line, technicians perform electrical connections, a thorough leak test, and final calibration before a road test.
Weighing the aftermarket option
Aftermarket installations typically cost 25 to 30 percent less than the factory-fitted CNG variant premium. The primary advantage, according to the source, is converting models without a factory CNG option. For example, Maruti Suzuki's factory CNG cars are only manual, so an automatic requires an aftermarket kit. Popular SUVs like the Hyundai Creta and Kia Seltos also lack factory CNG, pushing owners to the aftermarket.
Only petrol cars can be converted, as CNG is spark-ignited. Diesel cars and strong hybrids are not recommended for conversion. The source advises against converting cars in poor mechanical condition, as it can affect engine health. For a well-maintained car, a properly installed aftermarket kit can be reliable long-term.
