Fuel Injectors - 39LB/HR (8pk)

The FAST Electronics Fuel Injectors 39LB/HR 8-pack (part number 30397-8) represents precision-engineered fuel delivery for GM LS-series engines. This set of eight high-impedance injectors is designed for LS3 and LS7 specifications, featuring industry-standard EV6/USCAR connectors that ensure compatibility with most modern LS-based engine management systems. At 39 pounds per hour flow rate, these injectors deliver the refined atomization required for optimized combustion across a wide range of RPM and load conditions.

The 39LB/HR specification balances mid-range performance with street-manners reliability—a proven sweet spot for naturally aspirated and moderately boosted LS builds. High-impedance design (typically 11–14 ohms) allows these injectors to operate on factory ECU outputs without requiring a separate driver module, simplifying installation in both stock and modified harnesses. The EV6 connector format is the modern standard across aftermarket LS tuning, making replacement or upgrade straightforward when engine specs change. Each injector in the 8-pack undergoes flow testing to ensure consistency across all eight cylinders, critical for even air-fuel distribution and stable idle quality.

These injectors suit builders stepping up from stock fuel delivery without overspecifying for their power target. Typical applications include mild cam grinds, intake upgrades, and conservative tuning in naturally aspirated LS3/LS7 street engines where 39 lb/hr provides headroom without requiring dedicated fuel system redesign. The LS-length body ensures proper fit in standard LS cylinder heads and compatible aftermarket heads designed to LS specifications.

When sourcing fuel injectors for LS-series builds, flow rating directly impacts idle quality, transient response, and tuning flexibility. The 39LB/HR FAST injector set offers a practical middle ground—larger than stock, capable of supporting meaningful performance gains, yet small enough that fuel control remains precise at cruise and part-throttle operation. Installation requires basic hand tools and familiarity with injector rail removal; no special adapters or modifications to LS architecture are needed.