Hill Two

1940s Hill 2R Generator

Back in 2019, we published a story about the Hill Diesel and it’s connection to Ransom E. Olds, the founder of Oldsmobile. You can see that story online at https://www.dieselworldmag.com/diesel-engines/over-the-hill/ . Hill Diesel was formed after Olds bought the controlling shares of Bates and Edmonds Motor Company in 1924, renaming it Hill Diesel Engine Company after the man he placed in charge, Harry Hill.

Gary Nau’s Hill 2R 10 KW generator set is of unknown age and lineage. Based on serial number and other details, we think the engine is mid to late ‘40s. As a generator set, it doesn’t appear to be the type sold by Hill, nor does it appear to be of a military origin. It mounts a Century generator, while Hill commonly used GE units. Most likely, the engine was purchased as a power unit and converted by an outside vendor. The 2R engine was rated for a maximum of 23 horsepower at 1800 rpm, but this generator produces 60 cycles at 1200 rpm and at that speed, the engine was rated for 18 horses max and 13.5 continuous. Doesn’t seem like a lot but look at the nearby torque graph and note that 82 lbs-ft of maximum torque (60 lbs-ft continuous). At 1200 rpm at the continuous duty power level, the engine used about 0.85 gallons per hour.

In power unit form (engine base, radiator and sometimes a bellhousing), the 2R was 1380 pounds heavy. The generator would about double that weight. The fuel tank is a small temporary piece. In actual service, the engine would likely be fed from a larger tank or even a 55-gallon drum.

Bates and Edmonds had a good line of oil engines so the transition to full diesel was a natural progression as the technology became more easily implemented. By 1928, Hill’s A and B-Series oil engines had been adapted into indirect injected diesels and the more compact Model C soon emerged. Olds pushed the Hill sales amd engineering teams to put the Model C into motor trucks and even did a long distance run in a Hill repowered truck, but the market was small for diesel trucks in the ‘30s was uphill and the Model C remained primarily a stationary and marine powerplant.

The Big R

The Model C had a long market life but when it got long in the tooth, Hill engineers worked over the basics to make the Model R. It was similar to the Type C but destroked to 5.5 inches and used individual, camshaft-driven Bosch APF injection pumps for each cylinder rather than the very imprecise inline Hill pump. The Model R was offered in two (2R), four (4R) and six (6R) cylinder configurations and all had the same 3.50 x 5.50-inch bore and stroke. The first Models Rs were sold alongside Model Cs but the older engines soon faded away.

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The two-cylinder displaced 106 cubic inches from a 3.5 x 5.5-inch bore and stroke. It delivered a maximum of 23 horsepower at 1800 rpm, with the continuous rating a more modest 17.5 hp at 1600. The 4R displaced 212 cubes, made 51.5 hp at 1800 max (34 @ 1600 continuous). The 6R was 318 cubic inches and made 78 hp at 1800 max (52 @ 1600 continuous). The continuous torque lines of all engines were virtual straight lines from 600 to 1500 rpm, delivering 60, 108 and 175 lbs-ft respectively. All had a 15.5:1 compression ratio. Some engines were equipped with individual compression releases for each cylinder so they could be hand started.

Over the Hill

The history of Hill Diesel Engine Company is a fairly short read and not much documentation remains to mark it’s passage. World War II started out as a sales booster for Hill but the company was not big enough to fight it’s way anywhere near to the top of the burgeoning diesel engine marketplace. In a wartime technical manual listing the generators available for the Signal Corps, of the 100 models listed, three Hill sets are there; the PE-85-L, PE-205-A and PE-207-A, the first being a big 25KW unit with a 6R and the other 15KW units with 4R power.

With the R-Series engines, Hill adopted Bosch APF injection pumps. They were camshaft driven via rollers and each cylinder had a separate pump. The injectors are listed as being from Ex-Cell-O, which was one of the big diesel fuel injection manufacturers of the day.

The generator set is mounted on a skid but some time in the past, an owner put a pair of axles under the skid. Before he got it, Gary said the Hill was used to power a remote homebuilding site.

In April of 1942, Hill Diesel was folded into the Edwards Company of New York, which soon changed it’s name to the Rogers Diesel and Aircraft Corporation, though Hill retained it’s plant location and name. Drake America Corporation acquired Hill Diesel in 1948 as one of it’s first corporate acquisitions and Hill continued in Lansing, Michigan, until October of 1952, when Drake shut it down for reasons that remain unclear. The Model R would be Hill’s last engine design.