The ED was the first diesel built in-house by an American truck manufacturer and it was a mighty good first shot. With a 4.375 inch bore and 5.75 inch stroke, it made 131 horsepower at 2000 rpm from 519 cubic inches. The seven-main crankshaft with insert bearings was more than able to carry the 382 lbs-ft of torque that came in at 1300 rpm. The c ylinders were dry sleeved and this engine was claimed to be the first HD engine to use split-skirt aluminum pis tons. Another first claimed was a tongue-and-groove connecting rod cap lock. Mack was one of the first to have water cooling around the injector nozzle and used an extra long injector for maximum cooling. Like many diesels of the era, it had two cylinder heads, each covering three cylinders. The engines generally used Bosch inline injection pumps and Ex-Cell-O injectors.
Visible in this cutaway are the crossflow head, with the Lanova power cell, the tongue-and-groove rod caps, dry cylinder liners and split-skirt pistons. The crankshaft main journals were 3.5 inches in diameter. The engine weighed nearly 2,000 pounds.
Some companies often step ahead of their competition. At times, that’s a step too far and requires two steps back, but not this particular time. When Mack Trucks Inc. embarked on the road towards diesel engines in 1927, they were charting the course for an entire industry and took no steps back. Their careful research yielded a viable truck diesel that was successful within the limitations of the market then. Mack was one of the few truck manufacturers to build their own engines. They weren’t the first company to offer a diesel option in big trucks, though they were at the forefront of those that did, but Mack gets the nod for being the first truck company to build their own diesels in-house.
Progress, Mack started looking at diesels in 1927. During a research period that ran from ‘27 into ‘35, they sent engineers to study in Europe and even bought engines to test in Mack trucks, including one from Mercedes Benz. Starting in 1936, they offered diesels from Buda and Cummins as options in certain trucks and that also added to the teachable moments. At Mack’s engineering research facilities in Long Island City, New York, and Plainfield, New Jersey, engineers tested a variety of diesel types, including twoand four-stroke, sleeve valve, direct injection, air cell, swirl chamber and Lanova. By 1935, they had settled on the Lanova system.
If you’ve been reading Vintage Smoke for a while, you will have noticed the Lanova system has come up a lot. With good reason. Designed by Franz Lang in Germany, the Lanova energy cell was quite popular in the early days of diesel. We covered it extensively in the July 2019 issue and the nearby illustration shows how it works. Suffice it to say, it was a smooth, gentle way to achieve compression ignition that didn’t put excessive strain on components. It allowed for diesel engines to be cost-effectively downsized to better fit motor vehicles but without too many compromises of output and with great fuel economy.