High-horsepower engines don’t just need more fuel — they need stable, predictable fuel control. The Spool Performance Split Fuel Surge Tank was designed specifically to solve the real problems that show up when direct injection and port injection are pushed hard.

At high load, the factory high-pressure fuel pump for direct injection creates rapid pressure pulses on the low-pressure side of the system. When DI and PI share the same fuel supply, those pulses can travel through the fuel rail and cause unstable pressure at the port injectors, leading to inconsistent injector flow and tuning headaches. This is one of the most common causes of erratic PI behavior on high-power builds.

Our split surge tank physically isolates the DI and PI fuel circuits. One dedicated pump feeds the DI system, while up to three pumps supply the port injection system, keeping pressure smooth and consistent where it matters most. The result is stable PI fueling, cleaner injector control, and far more predictable tuning, even under heavy boost.

The separate PI circuit also allows you to properly boost-reference the port injection system, maintaining consistent injector differential pressure as boost rises. This keeps PI injector flow linear, improves safety at high load, and gives tuners precise control over fueling across the entire RPM and boost range.

Machined from billet 6061 aluminum, the surge tank is built for durability and long-term reliability in high-ethanol and high-horsepower environments. Installation is handled with a true plug-and-play wiring harness, running from the battery all the way to the fuel pumps, complete with properly sized relays and fuses — no custom wiring, no shortcuts.

Key Highlights

Designed specifically for high-horsepower DI + PI setups
Billet 6061 aluminum construction
Supports up to 4 fuel pumps
- 1 dedicated pump for Direct Injection
- Up to 3 pumps for Port Injection
Isolated DI and PI fuel circuits to eliminate pressure pulse interference
Enables boost-referenced port injection
Complete plug-and-play harness from battery to pumps, including relays and fuses

This is fuel system architecture done the right way — stable, scalable, and built for serious power.

B48/B46 GEN2