Railroad Trains for the Soul: EMD SD89MAC
In 2000, General Motors Electro-Motive Division designed the 4,500-horsepower SD89MAC diesel locomotive, the less powerful version of the 6,000-hp SD90MAC. EMD’s prototype, No. 92, is the only 89MAC ever built and has an interesting story. It looks identical to the 90MAC Phase II locomotives, two of which were assembled as the builder’s demonstrators, Nos. 90 and 91. Mechanically, the major component unique to the lone SD89 is an extremely rare 12-cylinder configuration of the four-cycle 265H diesel engine, compared to the 16-cylinder H-engine for the SD90.
According to Trains Magazine’s Locomotive 2014 issue, nos. 91 and 92 have since been reused as testbeds in preparation for EMD’s Tier 4-emissions-compliant locomotive production. The former unit was retrofitted with the prototype for the new 12-1010J freight engine while the latter was reequipped with the 20-cylinder Caterpillar C175 diesel for passenger duty. As a result, both units are only used for mechanical testing purposes and can no longer be moving like a real locomotive. The SD89MAC’s prime mover compartment was heavily modified with a full-width carbody that is normally seen on modern passenger locomotives, including the EMD F125.
What you probably didn’t notice is that a lot of EMD diesel names containing the number 9 (the second digit of the model number) appear to represent a V12 engine, be it the 645, the 710, or the 265. Examples include the GP39, GP39-2, GP39X, SD39, SDL39, GP49, GP59, F59PH, F59PHI, F69PHAC, and now the SD89MAC. By the time EMD introduced the SD70ACe-T4, the V12 engine has become ideal for a Tier 4 freight locomotive. Normally, EMD named its two-cycle engines after their cylinders’ displacement in cubic inches. However, the 265H designation comes from the metric length of the cylindrical bore in millimeters. That engine could have been named the 1010H, not to be confused with the Tier 4 1010J prime mover. Both types have a displacement of 1,010 cubic inches per cylinder.
Here’s a photo of what appears to be the unmodified SD89MAC. I love seeing obscure diesels like this one.
Photo credit: Pechristener
