Isuzu CNG Powered Trucks

It has been a year since Isuzu first announced its intention to introduce a number of Compressed Natural Gas (CNG) powered trucks into the Australian market. These models were to be Isuzu’s offering to the market for customers wanting to head down the alternative fuels route, reduce environmental impact and dip a toe into the green economy. The N Series and F Series models chosen are in the top selling mass segments running around Australian cities today.

The introduction of these new trucks follows a number of trial vehicles brought into Australia by Isuzu back in 2002 to test the efficacy of CNG power in Australian conditions. Lessons learned from this experiment, especially the trucks still running in the Gosford City Council fleet, have stimulated the all-new design specification of these latest introductions. This is a full model release and these trucks will be on sale in dealer forecourts in the coming months.

“As a company, Isuzu has two alternative fuel options,” says Phil Taylor, Isuzu Director of Sales and Marketing.” One is the diesel electric hybrid, and I won’t rule out Isuzu introducing the hybrid onto the Australian market in the future. At this time, we believe that the environmental benefits available from a hybrid are, at best, token. In order to perform at their best they require very specific traffic conditions.

“I acknowledge that CNG vehicles have some limitations of their own and that they won’t be suitable to certain applications. However, we see an ideal fit for these models in metropolitan pick up and delivery (PUD) tasks. They will provide environmental and operational savings, whatever the traffic conditions and whatever the traffic speed.

“The refueling requirements of CNG trucks practicality dictates that ‘back to base’ type operations will be the main target. It is refueling which presents us with the greatest challenge to overcome. Previous concerns, such as operating range and reduced power compared to diesel have been overcome. In our view, refueling infrastructure remains the biggest obstacle to wider adoption of the technology.”

The models being introduced are an NLR 200 CNG, NPR 300 CNG, FSR 700 CNG and FSR 850 CNG. GVM ratings are 4.5, 7, 12 and 14 tonnes with power ratings at 130hp for the N series models and 220hp for the F series options. These four models probably cover an area of the market, below 15 tonnes, representing the largest proportion of the number of trucks sold in Australia. 

The NLR and NPR both use a naturally aspirated 4.5 litre four-cylinder engine putting out 129hp (96kW) at 3200rpm and delivering 353Nm (260ft lb) of torque at 1400rpm. The engine has been developed by Isuzu in Japan purely as a gas engine but based on the equivalent diesel engine block already seen here.

For the FSR models, the engine is the 7.8 litre in line six cylinder putting out 217hp (162kW) at 2400rpm, and 735Nm (542ft lb) of torque at 1400rpm. These engines include a turbo and intercooler as well as the fuel technology included in the smaller models. 

All of the Isuzu CNG engines use a spark ignition system with multipoint CNG injection introducing the fuel to the combustion chamber. There is also a three-way exhaust catalyst to help reduce exhaust emissions. As a result, the trucks are fully compliant with ADR 80/03. In fact, PM (particulate matter) is virtually zero in the emissions of the CNG engines. PM is of particular concern in urban areas where the health implications of particles in the air are constantly of concern. 

“The Isuzu CNG range very comfortably exceeds Euro 5 and Japanese New Long Term 05 (J-NLT 05) environmental ratings required under ADR 80/03 legislation, not due for introduction until 2011,” says Isuzu Product Planning and Engineering Support Manager, Colin White. “These models even meet some performance criteria under proposed Euro 6 standards, for which an introduction date is yet to be finalised for Australia.

“Emitting zero PM and less than 0.2 grams of NOx per kilowatt hour, the Isuzu CNG trucks better the maximum PM and NOx engine exhaust emissions required under proposed Euro 6 requirements which mandates a 50 percent reduction in PM, and 77 percent reduction in NOx from Euro 5 ratings. Overall, the CNG engines provide greenhouse gas reductions in the order of 15 to 30 percent, and these are conservative figures.” 

The N Series CNG trucks use the Isuzu AMT transmission as standard, with a five-speed in the NLR and a six speed in the NPR. Also common to both models are two 150 litre steel CNG tanks offering a range of over 300 kilometres on a combined urban/highway cycle, loaded to full GVM. Both models also feature an idle stop fuel saving system, similar to the system offered in hybrid trucks, which turns the engine off at idle once the AMT selector has been placed in neutral and the park brake engaged.

The gearbox used on the larger F Series models is Isuzu’s own 6-speed MZW-6P manual transmission with air assisted shift and synchromesh on gears 2-6. Fuel tanks consist of a single 150 litre carbon fibre wrapped aluminium tank, two 100 litre steel tanks and an additional 90 litre steel tank for a total fuel capacity of 440 litres, which Isuzu says provides the trucks with a combined cycle driving range of about 400 kilometres.

Fuel availability is obviously a crucial consideration when looking at the CNG powered trucks. There are currently seven publicly available CNG refueling sites in Australia. Three are in Canberra, two are in Sydney and two are in Melbourne. A further four CNG service stations are expected to open later this year. In addition to the public facilities, some corporate operations and government depots do already have access to CNG refueling on site. 

The number of outlets where the gas is available is bound to grow over the next few years. Isuzu is not the only manufacturer introducing models powered by CNG. These new engines are part of a number of new technology CNG powered engines becoming available. The more CNG vehicles there are on the road the more fuel outlets will appear.

Phil Taylor points to the example of Iran where CNG accounts for 7% of all the transport fuel used. Just five years ago the proportion was zero. The country now has 900 refueling facilities for CNG in the country. Government support and investment has led to the swift growth in a CNG refueling infrastructure.

“We are confident we will see several CNG refueling stations available to the public in all of the capital cities and in some regional areas,” says Phil. “We also believe a number of larger fleets will commission their own facilities on their own sites as the benefits of CNG become more evident and the future introduction of an emissions trading scheme comes on stream.”

Toll and TNT are both engaged in environmental programs as part of the development of their fleet. They are committed to reducing emissions across their operations. CNG has been identified as forming a part of this initiative. 

“We think the industry should be aiming for a market penetration of natural gas powered engines of 10 percent,” says Dean Stuhldreier, Isuzu National Fleet Sales Manager. “That equates to around 1500 units per year and the vast majority of these would be sold in the high volume weight segments.”

Any decision to use CNG, on the evidence of Prime Mover’s driving experience, would come down to other considerations and not performance. Truck drivers used to the equivalent Isuzu in their daily working lives will find their driving experience little changed when swapping to CNG, although definitely a little quieter.

Taking the trucks out on the road will give just about every driver the same initial impression, one of an eerie silence. These engines are extremely quiet, and in busy traffic, it is often difficult to pick out whether the engine is running or not. Spark ignition engines do run quietly, there is none of the familiar diesel knock. It has also got to be realised that these engines do use a similar block to their diesel counterparts and some of the quiet running can be attributed to the thicker walls of the diesel engine’s design. 

There is also no aspect of the performance of the truck compromised, in any way, by being fuelled by CNG. Over the years, experience with gas conversions has created folklore around gas power. There is a perception gas engines are less powerful and less responsive. This is probably due to cheap gas conversions and a lack of adequate programming in engine mapping to compensate for different fuel characteristics. 

In fact, spark ignited gas engines are very free revving and a quick blip on the throttle is answered with immediate results. There is plenty of torque available from the engine and in the larger F Series, in fact, there is more than in its diesel equivalent. However, due to the much lower engine noise the driver can get a mistaken impression that the truck is not working very hard. 

These trucks are already top sellers in the PUD transport segment. The only thing that is different is the power plant. Transmission ratios have been adapted to suit the CNG engine performance. Our relatively short driving experience in the trucks demonstrates they are well specified and suited to the task, as one would expect with an Isuzu truck. 

The decision for an operator to consider CNG is much more about access to refueling and the economics of buying the truck for a particular application, that is getting the monetary savings needed to offset the higher price of the initial investment in the truck. 

Consideration of the refueling is simply a matter of geography. If there are refueling facilities available on a route or at a depot, operators will be able to bring CNG power into the decision-making mix. Some PUD operations are unlikely to see any chance of CNG fuel access any time soon. Any decision will need to consider fleet flexibility and vehicle resale value on top of the access to fuel issue. 

Operating experience with CNG trucks will soon give a wider group of trucking operators a handle on which applications will suit CNG power and which won’t. There are running cost savings to be had and these are likely to increase rather than decrease, with the chance of the price of diesel increasing in the future being very high. This is where the CNG vehicle is likely to make its biggest impact, where running costs can be significantly reduced without compromising operational considerations. ?

Purely from a driver’s perspective, the new CNG trucks are a positive experience and life will certainly be quieter, with enough performance on tap to get the job done with ease. The downside may be from the limited opportunities to refuel and the limitations that may cause.