The RailKing SD90MAC measures 143/4 inches coupler to coupler, or 59 feet long in O scale. That’s a full five inches short compared to an accurate O scale model.
Length, however, does not a locomotive make, and the RailKing model has plenty of cast-in hatch and screen detail to please operators. The gold Canadian Pacific logo is exceptionally well done, and the overall paint job is smooth and crisp.
On the test track the SD90MAC, with ProtoSound 2.0 and its “cruise-control” feature turned on, recorded a low-speed average of 4.2 scale mph and a high-speed average of 74.2 scale mph. Drawbar pull for the 4-pound, 7-ounce, dual-motored and traction-tired engine is a sturdy 2 pounds, 3 ounces, which works out to well over 100 free-rolling freight cars. This was performance worthy of a Premier line diesel locomotive.
Using our 25-car mixed make and vintage freight train, we clocked the SD90MAC at 59.8 scale mph. We are still awaiting the release of the MTH DCS controller, so we operated our test sample in conventional mode only.
All conventional features, such as freight-yard sounds, worked well. The sound package is robust and is an attention-getter coming from such a diminutive package.
If you are building an O-31 empire and want to run the latest in diesel power on your tight curves, then the RailKing SD90MAC may have your name on it!
