As fuel prices fluctuate and environmental concerns grow, many vehicle owners with LPG - fitted cars are wondering: Can LPG kit be converted into CNG? This question, along with related queries about converting LPG to natural gas, retrofitting gas engines to CNG, and the cost and worth of such conversions, has become increasingly common. To help you navigate these uncertainties, we break down the facts, possibilities, and practicalities of switching from LPG to CNG.
Is It Possible to Convert LPG to CNG? The Technical Reality
The short answer is yes, but it’s not a simple “swap” of parts—converting an LPG - equipped vehicle to run on CNG requires a complete overhaul of the fuel system. LPG and CNG have vastly different properties: LPG is stored as a liquid under low pressure (around 8 bar), while CNG is stored as a compressed gas at extremely high pressure (up to 200 bar). This means almost none of the existing LPG components can be reused for CNG.
To convert an LPG vehicle to CNG, you’ll need to replace every key part of the LPG system with CNG - specific components, including:
A high - pressure CNG storage cylinder (certified to withstand 200 bar pressure, unlike LPG’s low - pressure tanks).
High - pressure fuel lines and fittings (designed to handle CNG’s intense pressure, which LPG lines can’t tolerate).
A CNG pressure regulator (to reduce the high - pressure gas from the cylinder to a level safe for the engine, a far more robust device than LPG’s regulator).
CNG - compatible injectors or a mixer (calibrated for methane, the main component of CNG, rather than LPG’s propane/butane blend).
A CNG refueling receptacle (different from LPG’s refueling nozzle) and a pressure gauge (to monitor CNG levels, which operate differently than LPG gauges).
In essence, converting LPG to CNG is less about “converting” the existing kit and more about installing a brand - new CNG system while removing the old LPG components.
Can I Convert LPG to Natural Gas?
When people ask “Can I convert LPG to natural gas?” in the context of vehicles, they’re usually referring to converting an LPG - powered car to run on CNG (since CNG is primarily composed of natural gas).
As explained above, this is possible, but it’s a full system replacement—not a tweak to the existing LPG setup.
It’s important to note that “natural gas” in vehicle terms is almost always CNG (compressed natural gas) for on - road use. Liquefied natural gas (LNG) is another form,
but it’s rarely used in passenger cars due to its ultra - low temperature storage requirements. So, if your goal is to switch from LPG to natural gas for your vehicle,
CNG is the practical option—and it requires the full system conversion outlined earlier.
Can You Convert a Gas Engine to CNG? Yes, But Engine Compatibility Matters
A “gas engine” here typically refers to an engine designed for LPG or even petrol (gasoline). The good news is that most petrol engines (and many LPG - converted petrol engines) can be converted to run on CNG—but only if the engine is compatible.
Key factors for engine compatibility include:
Engine size: Smaller petrol engines (1.0L to 1.5L) are the best candidates. Larger engines may experience more power loss with CNG (since CNG has a lower calorific value than petrol or LPG) and may require more extensive tuning.
Engine age and condition: Older engines (pre - 2010) may need additional modifications (like hardened valves) to handle CNG, as CNG burns cleaner but can be less lubricating than petrol or LPG. Well - maintained engines, however, often adapt well to CNG.
Fuel injection type: Modern sequential fuel injection engines are easier to convert to CNG (with sequential CNG kits) than older carbureted engines, which may require simpler venturi - style CNG kits.
Crucially, diesel engines are not easily converted to CNG without major overhauls (like adding spark plugs), so if your LPG vehicle is a diesel conversion, converting to CNG is far more complex and often not cost - effective.
Can LPG Be Used in Place of CNG? The Risks of Fuel Mix - Ups
No—using LPG in a CNG vehicle (or vice versa) is extremely dangerous and will damage your car. As mentioned earlier, the two fuels have incompatible storage and delivery systems.
Putting LPG into a CNG cylinder would cause the cylinder to fail (since it’s not designed for liquid fuel), leading to leaks or even explosions.
Conversely, putting CNG into an LPG tank would result in insufficient pressure, causing the engine to run poorly or not at all, and could damage the LPG system’s low - pressure components.
Even if you’re considering “topping up” with LPG when CNG is unavailable, don’t do it. The fuels require entirely different systems, and mixing them is a safety hazard and a costly mistake.
Cons of Converting to CNG
High upfront conversion cost: As we’ll cover next, CNG retrofits are expensive—often more than the savings you’ll see in the first year.
Reduced boot space: CNG cylinders are larger and heavier than LPG tanks, taking up more trunk space.
Limited refueling infrastructure: CNG stations are less common than LPG stations in many areas, especially rural regions. If you frequently drive long distances or outside cities, refueling could be a hassle.
Potential warranty issues: Some car manufacturers void the engine warranty if you install an aftermarket CNG kit, even if it’s certified.
Verdict: Converting to CNG is worth it if you drive 15,000+ km per year (to offset the upfront cost) and live in an area with good CNG infrastructure.
If you drive less or have limited access to CNG stations, sticking with LPG may be more practical.
Final Tips for a Successful LPG - to - CNG Conversion
Choose a certified installer: Only work with workshops approved by the local transport department and kit manufacturers. Uncertified installers may cut corners, leading to safety risks.
Opt for a branded kit: approved kits from trusted brands (scyuncheng) are safer and more durable than unbranded kits.
Check your vehicle’s warranty: Contact your car manufacturer to see if a CNG retrofit will void the warranty. Some brands offer official CNG retrofits that preserve the warranty.
Update your vehicle documents: After conversion, register the CNG system with the Regional Transport Office (RTO) to avoid legal issues.
Converting an LPG kit to CNG is technically possible, but it’s a significant investment. By weighing the costs, benefits, and your personal driving needs, you can decide if making the switch is the right choice for you.
