Wabtec/GE ET23DCM
Here is my first locomotive blog post for 2023: the Wabtec/GE Transportation ET23DCM rebuild. As Class I railroads continue their obsession with rebuilding or modernizing their existing diesel locomotives, this 2,300-horsepower type is by far the most unusual of them all. It’s a CSX unit number 1727 (formerly 8077), an Electro-Motive (EMD) SD40-2 with its original 16-cylinder, two-cycle 645 diesel engine replaced by a General Electric Evolution Series six-cylinder GEVO prime mover. The concept of repowering specific locomotives with engines from different builders is not new. As far back as the 1950’s and 60’s, some diesels built by the American Locomotive Company (ALCO) and Baldwin had their own engines replaced by the EMD 567 versions. Some other Baldwin units and even a single GE switcher were repowered with ALCO engines. However, until just recently, there wasn’t a single EMD locomotive ever rebuilt with a GE prime mover (to the best of my knowledge).
The Tier 4-emission-compliant ET23DCM is the third SD40-2 rebuild program for CSX. The first is the SD40-3 model (introduced in 2010) that retained its 645 prime mover but rebuilt with microprocessor controls as well as the distinctive NRE-style cabs. Then, the second rebuild program is the SD33ECO, which debuted in 2017 and designated as SD40E3 by CSX. In this locomotive class, the 645 engines were replaced by the Progress Rail/EMD 12-cylinder 710ECO’s. The new ET23 units will fall within the same 1700 class as the SD33’s. Some Tier 4 rebuilds, like the Norfolk Southern GP34ECO, use selective catalytic reduction (SCR) to reduce exhaust emissions. However, because all Tier 4 GEVO’s feature exhaust gas recirculation (preferred by most freight railroads), you can assume that the inline L6 version for the ET23 is no exception. This eliminates the need for a tank full of urea, compared to SCR-equipped locomotives.
The installation of this unique engine allows the radiator section to increase its length on the old SD40-2 frame, accommodating the most sophisticated cooling system on a medium-sized rebuild. Normally, alternating current traction is a standard feature on new-build Tier 4 diesel locomotives such as the GE ET44AC and the EMD SD70ACe-T4, but direct current traction can be used for Tier 4 rebuilds, including the ET23DCM. As its model name suggests, the DC motors are retained and even the old EMD alternator is also still intact. Many of the locomotive’s other electrical components have been replaced by a more modern Wabtec control system for best communication with the GEVO engine. The origin of a six-cylinder GEVO came from the late 2000’s when GE proposed a locomotive model called the ES23DC, but it was never off the drawing board. Should this ever exist, the ES23 probably would have been intended for overseas export since North American railroads prefer locomotives with the 4,400-horsepower rating.
Check out the following video of the narrow-nose ET23 being tested between two wide-cab GECX Evolution demonstrator units (ES44AC number 2012 and ET44AC No. 2014).