Overview#
The Blue Star GM50-03 is a 50-kilowatt natural gas and LP standby generator powered by the PSI 5.7L NA — an eight-cylinder V8 naturally aspirated engine from Power Solutions International. It is rated at 50 kWe standby on both natural gas and LP across all voltage configurations from 120/240V single-phase through 347/600V three-phase.
Blue Star Power Systems pairs the 5.7L engine with a Stamford UCI224D alternator and DSE DCP7310 controller on a formed steel base. The OPU footprint is 80 × 38 × 52 in at 1,800 lbs. Level 1, 2, and 3 enclosures are available, with sound levels from 79 dBA (OPU full load) down to 64 dBA (Level 3) at full load.
PSI 5.7L V8: One Platform, Two Outputs#
The PSI 5.7L V8 block at 350 cubic inches powers both the GM50-03 (50 kWe) and the GM60-02 (60 kWe). The two models share the same 80 × 38 in footprint, the same engine architecture, and the same maintenance schedule. The GM50-03 uses a lower fuel delivery calibration that produces 50 kWe while leaving more output margin in reserve — a characteristic reflected in the more favorable altitude deration profile: GM50-03 holds full output to 4,200 ft while the GM60-02 begins derating at 1,200 ft.
Deration: Altitude Advantage#
The GM50-03 carries no published temperature deration and begins altitude deration only above 4,200 ft at 3% per 1,000 ft. This is notably more favorable than most gaseous generators in this class, which typically begin derating at 1,200 ft. For installations in the Rocky Mountain region, high-altitude construction, or elevated commercial sites, the GM50-03 maintains full 50 kWe output across a broader range than comparable units.
When to specify the GM50-03#
- 45–50 kW natural gas or LP standby at commercial, light industrial, school, or multi-family sites
- Installations above 1,200 ft elevation where the GM50-03's 4,200 ft deration threshold is the deciding factor
- Applications requiring 208-600V single- or three-phase output on both fuel types with equal output
- Sites where the 80 × 38 in OPU footprint is available and the same PSI 5.7L V8 platform as the GM60-02 is preferred for parts commonality
Our service experience#
The PSI 5.7L V8 at 50 kWe has significant headroom — 113 hp engine producing 50 kWe electrical output. This means the engine rarely approaches its thermal limits in standby operation, which is good for longevity but creates the same wet-stacking and fouling risks as all lightly loaded gaseous standby units. Annual full-load testing to 50 kWe is required. Natural gas supply pressure must be verified at the generator inlet under load — 736 ft³/hr at 11.0 in. W.C. requires proper regulator and supply line sizing. Spark plug inspection at each annual PM is non-negotiable on naturally aspirated engines of this type.
