Why does my Suzuki Khyber consume more fuel when running on CNG compared to petrol?

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Why does my Suzuki Khyber consume more fuel when running on CNG compared to petrol?

I switched to CNG for savings, but surprisingly my Khyber seems to consume more fuel on CNG than on petrol, especially in city traffic. Could it be due to poor CNG kit calibration, o r is my engine not well-suited for CNG use? How can I make it more efficient?

Gari Specialist asked on 11 Apr 2025 18:24:58 pm

1 Answer

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Gari Master - on 08 May 2025 17:45:27 pm

If your Suzuki Khyber is consuming more fuel on CNG Compressed Natural Gas than petrol, its likely due to several inherent characteristics of CNG and some potential tuning o r mechanical issues. Heres a breakdown:

Why CNG Consumption Feels Higher Than Petrol
Lower Energy Density

CNG has less energy per unit volume compared to petrol. That means:

You need more CNG to produce the same power as petrol.

This translates into higher consumption in km/kg compared to km/litre.

Engine Tuning

If the engine isnt properly tuned for CNG, it can run rich using more fuel o r lean reduced performance.

Spark timing and air-fuel mixture must be optimized specifically for CNG.

Reduced Engine Efficiency

On older carbureted engines like the Khyber, fuel injection control is less precise.

This results in less efficient combustion with CNG compared to petrol.

Worn Out CNG Kit o r Components

Faulty CNG pressure regulators, injectors, o r air-gas mixers can lead to inefficient fuel usage.

Clogged filters o r leaks can also waste gas.

Driving Style & Load

CNG engines often feel underpowered, so drivers may press the accelerator more, especially on inclines o r with A/C on—leading to more consumption.

Short Trips o r Cold Starts

CNG engines need time to reach optimal operating temperature. Short trips can reduce efficiency further.

Typical Consumption Figures
CNG: ~13–15 km/kg may vary based on kit and tuning

Petrol: ~12–14 km/l can feel more efficient due to better energy density

What You Can Do
Get the CNG kit tuned by a specialist adjust mixture, check pressure, timing.

Clean o r replace filters regularly every 20,000 km.

Check for leaks in the CNG system.

Avoid excessive idling o r aggressive acceleration on CNG.