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How to Convert Petrol Car to CNG & Things to Keep in Mind?

petrol to cng conversion

Converting petrol to CNG can reduce fuel costs and mitigate further pollution. CNG, short for Compressed Natural Gas, is an eco-friendly alternative that offers improved mileage and lower emissions compared to conventional fuels, such as gasoline. 

This article will explore the steps on how to convert your petrol car into CNG, the types of kits, and tips for making a smooth and safe transition. By the end of this article, you will have sufficient information to make an informed decision about CNG conversion for your vehicle.

Table of Contents

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Is It a Good Idea to Convert a Petrol Car to CNG?

Converting a petrol car to CNG can be an excellent option for reducing fuel costs and narrowing your carbon footprint. However, converting your vehicle to CNG can be expensive, and engine performance may slightly decrease. Additionally, you will lose some of your available boot space due to the installation of the CNG tank. 

Thus, if you prioritise savings and environmental sustainability over engine performance, conversion to CNG can be a good future investment.

Why Convert Your Petrol Car to CNG?

Compressed Natural Gas is a clean-burning alternative fuel made from natural gas. It is widely used in vehicles for its efficiency and minimal environmental impact from combustion. CNG is stored in high-pressure cylinders, allowing it to burn internally in the engine while reducing emission rates.

Increasing numbers of people are becoming interested in converting their petrol vehicles to CNG for various reasons. Here's a comparison of CNG and petrol, looking at aspects including cost, emissions, availability, and many other factors that would help you make a conscious choice:

Factor CNG (Compressed Natural Gas) Petrol
Fuel Costs CNG is generally cheaper than petrol, resulting in lower running costs.  Petrol is generally more expensive, keeping the running costs high.
Emissions CNG emits lower levels of harmful emissions, such as CO2 and NOx, making it more environmentally friendly.  CO2 and NOx emissions from petrol engines contribute to increased air pollution levels.
Fuel Efficiency CNG offers a lower energy density per cubic meter of gaseous fuel, so you may stop more often to refuel. As petrol offers a higher energy content, it provides better distance coverage before refuelling.
Availability CNG refuelling stations are not as widespread, but are being opened in various areas. Petrol stations are abundant, providing easier access to almost all areas.
Vehicle Performance CNG vehicles generally have slightly lower power and acceleration than petrol vehicles. Petrol generally offers better all-around driving performance in terms of power and acceleration.
Maintenance Costs Lower maintenance costs on CNG vehicles are attributed to cleaner combustion, which causes less engine wear. Frequent servicing is probable in petrol vehicles, especially concerning the engines and exhaust systems.
Environmental Impact CNG produces cleaner fuel with fewer carbon emissions, helping reduce the vehicle's overall environmental impact. Petrol has a high carbon footprint since more CO2 is emitted during combustion. 

Eligibility and Compatibility of Your Car for CNG Conversion

Before converting your petrol car to CNG, determine whether your vehicle is eligible and compatible with the conversion process. Here are certain key points to consider:

Criteria Description
Engine Type The vehicle must be fitted with petrol engines. Diesel-powered vehicles cannot be converted to CNG due to significant engineering differences and differences in combustion processes.
Engine Age and Condition The vehicle engine must still be functioning properly with no major mechanical breakdowns, as older machines on the roads are not supported by OEMS with CNG kits.
Engine Capacity It is suggested that engines ranging between 800cc and 2.5L size be candidates for CNG conversions for a car. Engines larger than that may need more adaptation.
Fuel Tank Space A vehicle should have enough space to accommodate a CNG cylinder. Most of the time, the gas cylinder can be placed in the trunk.
Emission Standards Vehicles must meet sound emission standards, as these will trigger a CNG installation due to their alignment with environmental sensitivities.
Existing Warranty Some warranties allow the manufacturer to decide whether to approve an aftermarket CNG conversion. Be sure to check on this warranty for your vehicle.
CNG Kit Type The kit must be compatible with the vehicle model. Not every kit is compatible with every make and model; therefore, ensure compatibility by consulting a certified installer.
Fuel Economy While CNG conversions typically reduce running costs, ensure that post-conversion fuel economy aligns with your driving requirements.

How to Convert a Petrol Car to CNG?

Converting a petrol car to CNG involves several key steps, including selecting the right kit, installing it, and testing. Here's a general outline of the process:

Step 1

Choose a CNG Kit

Select a certified CNG conversion kit that is specifically designed for the make and model of your car. These kits come fully equipped with a CNG cylinder, a pressure regulator, a fuel injection system, and all relevant attachments.

Step 2

Find a Qualified CNG Installer

Locate a well-trained and licensed installer of CNG conversion kits, ensuring they are familiar with CNG conversions and have a good connection with local authorities to guide you through the conversion process.

Step 3

Start Installing the CNG Kit

The CNG cylinder is fitted in the trunk or under the car, based on space availability and the make and model of the car. Regulators, valves, and piping are then included.

Step 4

Engine and Fuel System Conversion

When switching from petrol to CNG, certain engine modifications will be required. This includes adjusting the air-fuel mixture and even modifying the ignition system for the best utilisation of CNG.

Step 5

System Testing

This comprehensive test is conducted to verify leakage and performance after the conversion. Tests are conducted in both petrol and CNG for the exact vehicle, allowing the test to determine if the car performs well on both fuels.

Step 6

Getting Certified

Finally, a certified establishment will inspect a vehicle to ascertain whether it meets the stipulated emissions and safety standards. After the inspection, the car will get a certification of compliance.

Preconditions for Installing a CNG Kit in Cars

Certain mandatory checks ensure that your car will have a hassle-free process and efficient results before converting it to CNG; these include:

 

  • Vehicle Compatibility: Only petrol engines are suitable for conversion to CNG. Ensure your car has no major mechanical issues before proceeding.

  • Certified Installation Centre: Always visit a government-approved installation centre. Certified professionals ensure safe and legal installation.

  • Proper Documentation: Prepare all necessary paperwork, such as the car's registration and insurance. These are needed for legal certification after installation.

  • Space Availability: Verify that your car's boot has sufficient space for the CNG cylinder. In some cases, modifications are needed to allow installation.

  • Car Condition: The car should be in good working condition. Older, worn cars may cause problems after conversion.

  • Legal Compliance: Ensure your car complies with local emissions and safety standards. Otherwise, it might lead to legal issues.

  • Selecting the Right Kit: Choose the CNG kit that is appropriate for your car model and engine type, which requires professional advice for accurate selection.

Types of CNG Kits

There are numerous types of CNG kits. It would depend on the number of cars for specific engine configurations and power levels. Here is a summary of the most used CNG kits during vehicle conversion:

1. Carburetor Type CNG Kit

The carburetor-type CNG kit is used for older vehicles with a carburetor system for fuel supply. This kit contains a mixer, which mixes the CNG with air before it enters the engine. 

The carburetor kit is simpler and cheaper than others, so it's ideal for vehicles with older, carburetor-based engines. However, it may not be as fuel-efficient and performance-oriented as modern systems.

2. Sequential Gas Injection (SGI) CNG Kit

Sequential Gas Injection (SGI) CNG kit is for modern fuel-injected engines. With careful control, the system feeds CNG into each cylinder through individual injectors, resulting in improved mileage, a smoother drive, and lower emissions. 

SGI kits are more complicated and costly but offer far better performance for those whose vehicles demand a higher power output or significant driving.

3. Venturi CNG Kit

This venturi CNG kit is similar to the carburetor type but is mainly used on older fuel-injected engines. It mixes the air-fuel mixture with the CNG before entering the intake manifold. 

This system is less complex than the sequential system and is more cost-effective. Still, it may not offer the same efficiency or power output as the SGI kit, making it more suitable for smaller vehicles or low-performance engines.

4. Liquid Phase Injection (LPI) CNG Kit

LPI, or Liquid Phase Injection CNG kit, is an advanced system where the CNG is injected into the engine's intake in the liquid phase. The system offers superior performance benefits due to its cooling effect on air intake and increased fuel density, resulting in improved power and efficiency. 

They are used for high-performance vehicles or those with a higher demand for power; these kits provide smoother operation with improved fuel economy.

5. Dual Fuel CNG Kit

The Dual Fuel CNG kit is designed for vehicles that run on petrol and CNG. It allows the vehicle to seamlessly switch between the two fuels, providing the driver with flexibility. 

This kit includes a switch-over valve and a fuel management system to regulate petrol and CNG systems. If, however, one is looking for the benefits of CNG while also needing petrol, and CNG refuelling stations are scarce, then a Dual Fuel kit is ideal.

Advantages of Converting Your Petrol-Powered Car to a CNG-Powered Car

Converting your petrol-powered car to a CNG-powered car provides many benefits, and a few of them include:

Benefit Details
Lower Fuel Costs CNG is significantly cheaper than petrol, resulting in substantial savings over time, especially for frequent drivers. The reduced fuel costs make it an attractive option for those often on the road.
Environmental Benefits CNG is a cleaner fuel than petrol, leaving behind fewer harmful emissions. Therefore, the air is cleaner, and your vehicle is more environmentally friendly, causing considerably less harm to the surroundings.
Better Mileage Enjoy better mileage levels with a CNG vehicle, meaning you can cover more distance than petrol-only vehicles before needing fuel.
Minimal Engine Wear CNG cleaner combustion reduces carbon deposits in the engine; fewer carbon deposits result in less wear and tear on engine components, thereby extending engine life.
Lower Maintenance Costs Because CNG is relatively clean, it allows for the buildup of minimal carbon sludge in the engine. Even with CNG technology, a regular user can still save on repair and maintenance costs. 

Disadvantages of Converting Your Petrol-Powered Car to a CNG-Powered Car

While converting your petrol-powered car to CNG offers several advantages, there are also some disadvantages to consider before making the switch. Here are some of the potential drawbacks of converting to CNG.

Drawbacks Description
Initial Conversion Cost Converting to CNG can be expensive. You must pay for the CNG kit, installation, and any necessary modifications, making it unaffordable for some individuals.
Loss of Boot Space CNG tanks occupy valuable space in your car's trunk, reducing luggage capacity. This could make long trips or carrying large items difficult, affecting your overall car experience.
Performance Dip Some users may notice a dip in engine performance after conversion. While the vehicle might still run, pick-up speed and overall power may not be as high as when on petrol.
Reduced Range CNG has a lower energy density than petrol, resulting in a shorter driving range per tank. This means more frequent refuelling, which can be inconvenient, especially for long-distance travel.
Maintenance Costs While CNG is cheaper than petrol, the maintenance of the CNG system, including the tank and kit, can add to the overall cost over time. Regular servicing of the CNG system is essential to avoid potential issues.

How Does Installing a CNG Kit Affect Your Car Insurance Premiums?

CNG conversions increase premiums due to the added risk and modifications. Here's a breakdown of how installing CNG kits in your vehicle can affect car insurance premiums:

Increase in Insurance Premiums

A CNG-fitted car incurs higher maintenance and repair costs, which in turn increases the perceived risk to insurance companies. Consequently, insurance companies increase insurance premium rates for third-party liability and full-comprehensive coverage.

Requirement of Policy Endorsement

After the CNG kit is installed, the owner must notify the respective insurance company to get an endorsement in their policy to cover the CNG kit. If this is not done, they may reject any claim regarding a CNG modification.

Coverage Considerations

A CNG kit alters the risk profile associated with the vehicle, so the standard policies may not cover damages caused by CNG. Notifying your insurance company ensures that your policy provides full coverage for all unforeseen circumstances.

Change in Insured Declared Value

As fitted with a CNG kit, the value of your vehicle increases, resulting in a proportionate variation in the Insured Declared Value (IDV) and the damage premium. Following the installation of the kit, it is essential to reassess the IDV of your vehicle to ensure the proper calculation of premium and coverage.

Maintenance and Safety Tips for CNG Cars

Maintenance and care are the prime needs to keep your car running smoothly and safely with the help of CNG. The following are key maintenance tips for optimal operation and the life of your vehicle running on CNG:

 

  • Regular Engine Check-ups: CNG cars require regular engine check-ups, just like petrol cars. Schedule an appointment with your mechanic to optimise the engine's performance for peak efficiency.
  • Monitor the CNG Tank: The CNG tank is the system's lifeblood. Check for wear in the tank and have it refilled only at certified CNG stations to ensure the engine runs properly and provides a smooth journey.
  • Check the CNG Kit: The CNG Kit, comprising the reducer, valves, and piping nodes, should be periodically inspected for cracks or leaks. This saves from future disturbing repairs.
  • Clean the Fuel System: Cleaning the CNG system is essential. Carbon may build up gradually and start hindering fuel efficiency. This single, simple step can increase your engine's shelf life.
  • Replace the Filters: CNG cars have filters to prevent dirt and other impurities from entering the engine. These filters should be replaced regularly to prevent damage. This ensures the engine's condition.
  • Check for Leaks: Always be vigilant for any gas leaks. If you smell gas or notice a decrease in performance, it is essential to check it immediately. It's better to avoid all safety hazards.
  • Don't Ignore Service Warnings: Always follow the service intervals suggested by your manufacturer. If there's a service light or warning, don't delay fixing it. Development in the fields mentioned above can save you a considerable amount.

 

Converting your petrol vehicle to CNG is both eco-friendly and cost-effective. It reduces your energy bill, lowers your carbon footprint, and enhances engine performance. Although a little tedious, checking compatibility and going through a professional installation is well worth it, provided you reap the benefits of savings and go greener.

FAQs about Converting Petrol Car into CNG