CHILLICOTHE, Ohio — According to Kenworth’s national sales manager for specialty markets, Andy Douglas, the third annual update on Kenworth’s natural gas progress has customers approaching the topic more proactively. Attitudes are changing from “Let’s talk about it,” to “Let’s do it.”

And early trials are turning into orders as the whole natural gas experience goes from a “science project” to a solid business model, he said.

To underscore the point, a small trucking press group, including Trucknews.com, was invited to spend some informal time with Douglas and drive a selection of the Kenworths that had been assembled for the natural gas demo.

The Kenworth line-up

The Kenworth natural gas line-up covers the available market with engines from Cummins Westport and from Westport. This is highly confusing, but in simple terms, there is a 9-litre ISL-G and the just-available 11.9-litre ISX 12G, both of which are products from a joint venture between Cummins and Vancouver, B.C.-based Westport. These are spark-ignition natural gas engines. Then there is the15-litre GX, which is pure Westport, and features a diesel-pilot injection, with secondary injection of natural gas to develop the power stroke.

These three engines are available in the T440, T470, T660, T800, T800 SH (short-hood) and W900 sloped-hood models. As yet, none of the new-generation T680/T880 models are included in the natural gas line-up.

Of these, the ISL-G and the ISX 12G can be liquid- or compressed gas-fuelled. The GX 15-litre is only available fuelled by liquefied natural gas.

So, the demo trucks lined up included the T440, T800 and T800 short-hood. As a further complexity, different fuelling systems were featured, with long-term LNG partner Trilogy supplying some and relative newcomer Agility also represented, the latter with a back-of-cab CNG “cabinet” for the T800 SH.

Douglas says this underscores the gaining legitimacy of natural gas as a viable fuel. More competition means more innovation and competition. This should mean the price of gas storage on the truck – to date one of the major obstacles to its widespread adoption – will start to come down. It’s a self-fulfilling process, he said. As prices fall and demand picks up, increased volume will see prices falling yet more.

Getting on the gas

The Westport 15-litre has been around for several years and I have driven that in various situations, including a drive of a hundred miles or so pulling a loaded trailer up in Washington. There, the conclusion was that the 15 litre is easily able to hold its own against a diesel and at significant savings in fuel cost, once the issues of infrastructure are resolved. But the engine that had our focus – and very much that of the customers for the new fuel –is the newly arrived 12-litre Cummins Westport. That, said Douglas, has gotten everyone’s attention, as the current 350 and upcoming 400 have the muscle to replace a broad swath of engines in regional, line-haul and vocations where the already available 9-litre is pushed to deliver.

The 9-litre is more than adequate for P&D applications, as very successful demonstrations – and orders – at Coca-Cola and an Indianapolis bottling fleet Monarch Beverage attest. Coca-Cola has placed multi-truck orders for 9-litre gas distribution trucks; Monarch has said it is the company’s intention to run a fleet with 85% of the trucks natural gas-powered.

The whole natural gas scene got a boost with a recent announcement by UPS that the 800 tractor orders for the package fleet in 2014 would include no diesel-fuelled units. Some will be compressed, some liquid natural gas, said UPS COO at the recent ACT Expo in Washington, D.C.

All will be natural gas, he said. Kenworth is to get a major share of that, and certainly a good number of those units with be powered by the ISX 12G.

So our decision was to zero in on the 9-litre and the new 12, driving first a T440 P&D tractor-trailer around an urban course that included the Hwy. 159 through the middle of Chillicothe. This was followed by a stint with a T800SH with the ISX 12G. Both of these were CNG-fuelled, the first with tanks by Agility, the second with the BoC Trilogy set-up. And as a bonus, there was a roll-back chassis, unloaded, with the 12G that proved to be such a rocketship that it was returned after only a couple of convincing miles.

The 9-litre ISG-L is adequate for the P&D role, but it undoubtedly has to work for a living. It is fairly noisy – despite the low-noise combustion of natural gas – as it has to turn a lot more rpms to get the job done. Where we are used to keeping diesels in the low teens, the ISL need to rev out to 2200 rpm on a regular basis to keep up with traffic. The progress is aided by the well-matched Allison transmission that is a part of the ISL-G package, but when the fan kicks in as well, it’s all a little raucous.

Now the 12G is entirely different. It drives more like a diesel, in that low-speed torque is on the generous side of adequate. The demo truck had a nine-speed Eaton manual, so the usual 1500 rpm shift points were used and the truck made good progress, picking up the next gear well and getting on down the road. But it took some driving. The response to the throttle is very different from a diesel’s. There appears to be some surge, so that gearshifts are not quite as intuitive – nor as smooth, let it be said – as driving a well-mannered diesel. The biggest difficulty was accelerating away, which required very little throttle or time in-gear. The hardest shift was in the four-five and five-six, where considerable care has to be taken to back the throttle to zero before making the shift to get even a semblance of a smooth change.

The other rather disconcerting thing was the peculiar noise that accompanies deceleration of the engine. Cummins calls it a “bark,” and it is caused by the sudden release of boost pressure with the closing of the throttle. Its very odd and nothing like as pleasing as the waste-gate pressure release on a Golf GTI or a Subaru WRX, for instance.  

However, it did not impede the progress of the vehicle around the busy route of the demonstration.

At the end of the day, it was a convincing demonstration that natural gas in the shape of these three Cummins engines is a viable proposition, providing other factors are accounted for, most notably infrastructure concerns and the type of operation the truck is going to see. Still, there is that feeling that the technology is evolving. As it should. Just think about it: the diesel has been in trucks since 1931 when Clessie Cummins put his engine in an Indiana truck and drove it coast-to-coast. That’s 80-plus years of development. Natural gas heavy-duty engines have come a long way in a far shorter time and they will undoubtedly see a lot more development as we go forward.

But again, referring to Douglas’ opening comment, it’s no longer a science project. These trucks are relevant now, here to stay and with the fast-paced development of infrastructure and on-board fuelling, become more and more relevant every day.