Three new models for Kubota's mini series: Z602, D902 and WG972 launched for turf, off-highway, welder, power-gen use; power density key - industry news

Diesel Progress North American Edition, August, 2003 by Mike Osenga

Kubota Engine America Corp. has announced two new diesels and one new dual-fuel engine for the North American markets with the introduction of the Z602, D902 and WG972 dual fuel. The three new engines are part of Kubota's Super Mini engine range.

The Z602 is a two-cylinder, four-cycle, liquid-cooled IDI diesel with a bore and stroke of 72 x 73.6 mm and swept displacement of 0.599 L. The engine has two valves per cylinder and is rated 13.8 hp at 3200 rpm. A 3600 rpm version of this engine, due later this year, will be rated 15.5 hp. Dry weight is 132 lb.

The D902, a three-cylinder version of the Z602, has a displacement of 0.898 L and an output of 20.6 hp at 3200 rpm. A 3600 rpm version, due for introduction next year, will be rated 23.5 hp. Dimensionally, the D902 is only 3.3 in. longer than the Z602 Height and width are identical. It has the same bore and stroke as the Z602 and the dry weight is 158 lb.

The Z602 has the same width and 20 mm lower height compared to Kubota's Z482. Though it is 24 mm longer, for most applications the footprint and mounting locations are almost identical. This, Kubota said, allows OEMs to step up nearly 25 percent in power without re-engineering existing machines.

According to Dennis Bourgoin, vice president of sales and marketing for Kubota Engine America, Lincolnshire, Ill., the new engines are targeted primarily at turf equipment, compact construction equipment, platform lifts, welders and sweeper markets.

The key to the new engines is power density, Bourgoin said, as both new diesels deliver more in smaller or similar-sized engine envelopes. "This is what OEMs are requiring today," Bourgoin said. The D902 has the same footprint as Kubota's D722 with the output of the D905 diesel. Both engines are Tier 2 compliant and ready, he said.

The Z602 uses Kubota's Three Vortex Combustion System. The use of a built-in closed breather will be used for Tier 2 compliance. The bore and stroke of the Z602 have been increased without impacting the overall height or width through the use of a partially extended cylinder block and an oil pan with greater length, but less height. The result is the greater power density for the Z602.

The Z602 engine has a partially floating valve cover, a molybdenum disulfide (MoS2) coated piston and a counterbalanced forged crankshaft. The piston is 2.8 mm shorter than the piston for the Z482 which partially accounts for being able to accommodate the longer stroke without increasing the overall engine height.

Next year Kubota will introduce the model DF972, a new dual-fuel engine parallel to the new diesels. The DF972 is a three-cylinder, liquid-cooled dual-fuel engine (gasoline/LPG) with a bore and stroke of 74.5 x 73.6 mm and a displacement of 0.962 L. It will have the same output as the current DF1005 of 31 hp for gasoline use and 29.5 hp for LPG use at 3600 rpm.

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