Words by Ramsay Beacham
Photography by Lachlan Payne

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Fuel consumption vs The environment

The rate that any given engine emits carbon dioxide is directly proportional to how much and the type of fuel being burned.

For instance, with every litre of conventional unleaded fuel burned, around 2.4kg of carbon dioxide is released into the atmosphere.

Meanwhile, the burning of a litre of diesel fuel will result in something nearer to 2.7kg of CO2 gases, which is 13 percent worse than its petrol counterpart.

These numbers make the diesel engine look much worse than a petrol on the surface. However, you must also take into consideration that diesel engines are usually between 20 and 50 percent more fuel efficient than an equivalent petrol.

It might look deceivingly similar to the old engine, but the common-rail motor has an all-new injection system	The common-rail system uses a high-pressure pump, and the opening of the electronically controlled injector controls fuel

This puts the diesel engine back in front as far as the environment is concerned.
In a similar story, LPG vehicles emit 1.6kg of CO2 for every litre burned, which is considerably less than both petrol and diesel. However, LPG has a much lower energy content than unleaded fuels, and this means more must be burned to achieve the same result.

In order to compare the carbon dioxide emissions of different vehicles, simply obtain yourself an accurate estimate of the fuel consumption in L/100km. Then, multiply it by the relevant fuel type (ULP = 2.4kg/L, Diesel = 2.7kg/L, LPG = 1.6kg/L).

The ZD30 in its electronically controlled direct-injection state

The Test

As of the start of 2007, all-new light-diesel vehicles were required to comply with the Euro 4 standards. Previously, they were only required to comply with Euro 2.
This change has halved the limit of carbon monoxide emissions and reduced the particulate matter limit by 75 percent.

The GU Patrol wagon has been using the electronically controlled, direct-injection ZD30 turbo-diesel engine since 2000. Although it was a high-tech and relatively clean engine in its day, it wasn’t able to comply with the strict new emissions laws set in place at the start of this year.

Ian from West End Diesel operates the exhaust gas analyser, which also interfaces with the dyno	Apart from being electronically controlled, the original ZD30 fuel pump and injectors are not dissimilar to those of the bygone era

Another option for the Patrol was the TD42T. Even as an old school and very low-tech engine, it was still in production until last year.

Nissan’s solution was to discard the TD42T since it didn’t have a chance in hell of coming up to par. Then, it would upgrade the ZD30 to enable it to comply.

Despite retaining identical performance figures, the introduction of common-rail diesel injection onto the ZD30 was enough to reduce its impact on the environment.

Using an exhaust gas analyser, we measured the nitrous oxide emissions of the common-rail ZD30 to be 63 percent less than that from the older ZD30. That makes it markedly better for our environment.

Thanks

Thanks to West End Diesel, especially Ian for running the Patrols on the Dyno and on the exhaust gas analyser. Also thanks very much to Terry once again. He’s the preferred choice when it comes to Patrol owners.