The history of this family of diesel engines began even before World War II, when the 71-series 6-cylinder in-line diesel engine was introduced as the flagship product of the Detroit General Motors diesel engine division. Then, in 1957, a wider version appeared.
Interestingly, the 71 series designation refers to the cubic capacity of one cylinder, measured in cubic inches. It was exactly 70.93 cubic inches or 1162.4 cubic centimeters. Knowing the number of cylinders and their power, it is very easy to calculate the total cylinder capacity of the entire engine. For example, 8V71 had 8 times 1152.4 cubic meters. cm (about 71 cc) or 9296 cc Cm (9.29 liters).
In-line engines had one, two, four or six cylinders and were marked 1-71, 2-71, 4-71, 6-71, respectively. The blade blocks had 6, 8, 12, 16 or 24 cylinders and were designated as 6V71, 8V71, 12V71, 16V71 and 24V71. In addition, the two largest units used many smaller engine heads to maintain reasonable sizes and weights. Therefore, in a 16-cylinder engine, four 4-71 engine heads were used, and in a 24-cylinder engine there were up to four 6-71 engine heads. This solution also significantly reduced construction and maintenance costs, as many parts were common for small engines.
An interesting feature of the row units was their symmetry, which meant that individual parts of the equipment could be installed on both sides of the engine, depending on the application. Many models can also work clockwise or counterclockwise. Engines operating “left” were commonly used in boats and buses.
All 71 Series engines use the so-called Blower Roots in the rinse cycle.
They are installed on the outside of the air pump with pistons that prevent rotation and block, for pumping air at low pressure into the cylinders, through the core channels in the block and openings in the cylinder walls.
Engines had two or four valves per cylinder and a fuel injection unit (one injector per cylinder). They were available both in naturally aspirated versions (designation N) and turbocharged (T) and additionally equipped with an intercooler (TA). Trucks and buses also featured Jake’s famous brake (described here on DAF 95.500).
Series 71 vane engines reach 10 to 1800 hp In trucks, the most common were 6-, 8- or 12-cylinder units. The smallest of them, in their characteristic work, were called “Screaming Jimmy” or “Screaming Jimmy” (Jimmy as short for General Motors). They reached 238 or 304 hp. in a turbocharged version. The V8 variant developed a power of 318 or 384 hp, and the model with 12 cylinders was nicknamed “Buzzin Dozen”, and in the case of trucks, it developed a power of 450 to 550 hp.
There were more powerful options for the 12-cylinder version, reaching up to 900 hp. However, they were used in other vehicles than trucks or as industrial engines. Interestingly, each of these units reached maximum power after it exceeded the limit of 2000 rpm.
Series 71 was very popular in the United States. These engines powered almost everything. In the 1960s and 1970s, almost every intercity bus was equipped with such Detroit Diesel engines with 6 or 8 cylinders. The characteristic sound of six-cylinder in-line vehicles was also often mentioned by soldiers involved in World War II. Indisputable advantages, with simplicity at the forefront, made Detroit in various configurations a mass for infantry and tanks.
What did the civil engineers appreciate, what did the builders of military vehicles appreciate. There were many cars on American construction sites equipped with 71 series two-stroke diesel engines. Pollution of the environment, obviously, did not impress the engines - it was only important that the engine had oil and fuel.
After writing this article, I came across a lot of memories of people who used the 71 series engines. Almost everyone emphasized the same features. They had a characteristic sound of work, as well as a high level of noise. Low repair costs were significant - for example, replacing a full piston cost no more than $ 70, and an injector up to $ 20. Also mentioned were low power consumption in a lower rotation range and ... problems with compaction of earlier versions. Apparently, this problem was so big that in the 1960s, dark traces of motor oil could be seen on whole concrete sections of motorways (improvement was achieved through the use of o-rings). At the same time, this is evidence of the popular Detroit Diesel 71 series engines.