The 4.6-L 4HV1 natural gas engine, on display for the first time at ConExpo in March, is suitable for various industrial and mobile applications including water pumps, generators, and forklifts. (Photo by Ryan Gehm)

Isuzu Motors announces heavy-duty natural gas engine for off-highway

Isuzu Motors America used the ConExpo-Con/Agg 2017 stage to announce its intention to produce a dual-fuel capable (natural gas and propane) off-highway engine by mid-2018, leveraging its already-in-production on-highway CNG truck engine.

The 4.6-L 4HV1 engine, on display for the first time at the Las Vegas event, will have an expected maximum rated output of 81 hp (60.5 kW) at 1800 rpm and torque rating of 247 lb·ft (335 N·m) at 1400 rpm when operating in natural gas mode.

“We've studied the market for about two and a half years now and felt that it'd be a good fit for us to expand into the gas market [for off-highway],” Ken Martin, director of sales & service for the Powertrain Division of Isuzu Motors America, told Truck & Off-Highway Engineering. “We feel this engine is going to fill a hole that's out there. And we have a lot of experience and field usage already with the gas engine because the base engine model that we're using has been running since 2012 in our CNG truck market.”

The truck version is used in the U.S. and some Asian markets. “That's one of the reasons why we'll be able to come to the market competitively priced, a lot of the R&D has already been completed,” he said.

Since it's a “gasified” diesel engine design, the company is confident in the engine's durability and reliability, compared to some of its competitors which base their gas variants on gasoline engines, Martin said.

Some changes were necessary compared to the base diesel engine. “With gas there isn't any lubrication in the fuel, so you have to look at hardened seats, hardened valves. You have to lower compression ratio and change the piston rings, to name a few things. But again, we've already experienced that in real life on the truck side.”

4HV1 employs a fuel system from IMPCO, which also supplies the system for the on-highway model. Durability testing of the fuel system on the new engine is currently under way.

“We're programming the ECU to run off of natural gas and LPG, so with the flick of a switch you can switch back and forth,” he said.

Isuzu Motors believes the new gas engine will find a fit in various industrial and mobile applications including pump markets, generators, and forklifts.

Additional specs for the 4-cylinder vertical inline engine include:

• Bore x stroke = 115 x 110 mm

• Length = 35.4 in (900 mm)

• Width = 22.9 in (580 mm)

• Height = 38.2 in (970 mm)

• Dry weight = Approx. 815 lb (370 kg).

“After we launch the 4HV1 we'll see how it goes,” Martin said, referring to possible next steps for a natural-gas product range. “We're looking at launching a 6-cylinder version, a higher kW rating, as well.”

The engine had been well-received at ConExpo thus far, Martin said. Field testing with interested customers will begin this April.

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