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The conversion integrates a quartet of 75l CNG tanks that work in conjunction with the diesel engine for better fuel economy. Picture: SUPPLIED
The conversion integrates a quartet of 75l CNG tanks that work in conjunction with the diesel engine for better fuel economy. Picture: SUPPLIED

Isuzu Motors SA customers now have the option to buy the brand’s trucks fitted with a compressed natural gas-diesel dual fuel (CNG-DDF) conversion. The gas-propelled option is now available to as many as 20 long-wheel base models of the Isuzu N, F and FX series.

Compressed natural gas is non-toxic and is typically used as a substitute for petrol or diesel. It has been proven safe and reliable, with up to 14-million natural gas vehicles said to be operating in 80 countries. 

With fuel consumption the biggest operational cost in any truck fleet, Isuzu says the system, which is easy to operate, also reduces fuel consumption. The diesel engine remains standard and a button on the dashboard activates the switch between the diesel-gas mixture and 100% diesel mode.

An engine control unit determines the optimal gas-diesel fuel mixture in real time. Engine power, torque and efficiency are maintained in dual fuel mode, and Isuzu says fuel consumption can be reduced by up to 18%, but may vary depending on vehicle model, application and driving style.

The system automatically reverts to 100% diesel mode when the natural gas cylinders are empty or when a fault is detected with the CNG system. The gross vehicle mass (GVM) and gross combination mass of the trucks remain unchanged, however, the gas cylinders mounted to a CNG-DDF truck add to the tare mass, thus reducing payload. An axle weight calculator, available from TruckScience.com, is recommended as a valuable tool for calculating payload capacity.

The dashboard-mounted button used to switch from diesel fuel to a CNG-diesel combination. Picture: SUPPLIED
The dashboard-mounted button used to switch from diesel fuel to a CNG-diesel combination. Picture: SUPPLIED

More benefits of using CNG-DDF trucks are said to be a reduction in the carbon footprint as natural gas vehicles emit 20%-25% less greenhouse gases, and, with smoother combustion and less engine carbon deposits emitted, the life of the engine is extended. 

The conversion brings with it a quartet of 75l gas tanks for a total capacity of 300l. CNG gas prices now range between R8.50/l and R12.50/l and, using the maximum price, it will cost you R3,750 to refill the gas tanks. If your truck is fitted with the 400l tank option, it will cost an additional R9,844 to fill up with diesel costing 24.61/l at today’s prices. You would be looking at a total fuel bill of R13,594.

It will be up to takers to find value in the extra cost and the claimed 18% reduction in fuel consumption, while the snag to CNG reliance being the lack of a nationwide distribution network as refill stations are located only in the Gauteng region. Trucks fitted with the CNG-DDF system retain the standard Isuzu truck two-year/unlimited kilometre warranty and are insurable with a certificate of competence.

Conversion Pricing

Isuzu N-Series — R145,900

Isuzu F-series — R219,100

Isuzu FX- Series — R219,100

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