Overview#
The Blue Star MD1250-01 is a 1,250-kilowatt Tier 2 diesel standby generator built around the Mitsubishi S12R-Y2PTAW-1 — a 49.0-liter, 12-cylinder V-configuration turbocharged and water/air-intercooled diesel producing 1,881 HP at 1800 RPM. It is the largest of Blue Star's Mitsubishi V12 models, occupying the power band between the 1,000 kWe MD1000-01 and the V16-powered MD1600-01.
Blue Star Power Systems (North Mankato, Minnesota; DEUTZ AG subsidiary since 2024) assembles the MD1250-01 on a structural steel base with a Stamford S6L1D-H alternator (480/600V; consult factory for 208/240V) and DSE DCP7310 controller. It is three-phase only, available from 208V through 4160V.
The Mitsubishi S12R platform#
The S12R represents the top of the Mitsubishi 12-cylinder V-engine family. With a 6.69 in bore and 7.09 in stroke — larger than both the S12A2 (MD800-01) and S12H (MD1000-01) — the S12R achieves 49.0 liters from the same V12 architecture. The engine uses a water-to-air intercooler on a separate coolant circuit from the jacket water system, which means two independent fluid maintenance regimes at service. Jacket water pump flow is 489 GPM, with an additional 70 GPM through the intercooler circuit.
Mitsubishi S-series industrial diesels — particularly the S12R and the V16 S16R above it — anchor the megawatt-class generator market alongside Cat 3500-series and Cummins QSK engines. The platform has roots in marine and locomotive applications, providing duty cycle margins well beyond stationary emergency standby requirements.
When to spec the MD1250-01#
- 1,000–1,250 kW continuous emergency loads on three-phase power
- Large data center blocks, major hospital campuses, heavy industrial facilities, and large municipal infrastructure
- Sites requiring 4160V output at 1.25 MW without a step-up transformer
- The top of Blue Star's V12 lineup — 1,600 kW and above requires the V16 MD1600-01
Our service experience#
At 27,725 lbs OPU, the MD1250-01 is a structural engineering commitment — the equipment pad, access path, and rigging plan are as important as the generator selection itself. Fuel at full load (99.1 gph) means a 2,000-gallon tank provides approximately 20 hours of runtime. The 62,756 CFM radiator airflow and dual fluid maintenance schedule (jacket water + intercooler) make this a more complex commissioning and service project than the smaller John Deere–powered models in Blue Star's lineup.