255L/hr High Pressure Fuel Pump GSS341: The Ultimate Upgrade for High Performance Engines
What Makes the GSS341 Different from a Standard Fuel Pump
Standard fuel pumps are designed for stock engines and often cannot keep up with the fuel demands of a modified engine. When the fuel supply falls short, the engine runs lean, which can cause detonation, overheating, and serious engine damage. The GSS341 solves this problem with a high-flow design that delivers 255 liters of fuel per hour at 3 bar (44 psi) . But the real advantage shows up at higher pressures. At 80 PSI, a standard 255 LPH pump only flows about 132 liters per hour, while the GSS341 high pressure version flows over 210 liters per hour at the same pressure . This means your engine gets the fuel it needs even when boost pressure rises and the fuel rail pressure increases.
Power Handling and Flow Specifications
The GSS341 is rated to handle over 500 horsepower on gasoline, with some sources indicating up to 500-550 horsepower . For ethanol blends like E85, the pump supports around 400-450 horsepower because ethanol requires roughly 30% more fuel volume to achieve the same air-fuel ratio . The pump operates on 12V DC and has a maximum flow rate of 318 liters per hour . Here are the key flow numbers at different pressures:
- 255 LPH at 3 bar (44 psi)
- 230 LPH at 4 bar (58 psi)
- 225 LPH at 5 bar (73 psi)
- 208 LPH at 5 bar (73 psi)
- 178 LPH at 6 bar (87 psi)
- 120 LPH at 7 bar (102 psi)
Physical Dimensions and Fitment
The pump body is 39.2mm in diameter and 120mm long, weighing just 0.366 kg . Its compact size allows it to drop directly into most stock fuel pump hanger assemblies without any cutting or modification . The inlet fitting is 8mm, and the outlet fitting is 11mm, both designed for hose barb connections . The GSS341 has the inlet and outlet ports offset at 180 degrees, meaning they point in opposite directions . This is important to know because the newer GSS342 model has the ports in-line, so verifying the orientation before purchase is critical.
Vehicle Compatibility
The GSS341 is a universal pump, but it is commonly used as a direct replacement or upgrade for many popular import vehicles. Coverage includes most Acura and Honda models, as well as Subaru Impreza WRX and STi (1993-2000), Mitsubishi 3000GT VR-4, and Toyota Celica GT-4 . Always check the physical orientation of your existing pump before ordering, as some late-model Subaru and other vehicles require the GSS342 with inline ports .
Installation and Pre-Filtration
Installing the pump without a proper pre-filter is a common mistake that leads to early failure. Walbro recommends using a depth media filter that acts as a wicking mechanism, feeding fuel to the pump even when the filter is only partially submerged . This prevents the pump from running dry during cornering or low fuel conditions. The optional universal installation kit includes a high-quality filter, a wiring harness with safe connectors, and all necessary hardware . Using old or clogged filters with a new high-flow pump restricts flow and can cause the pump to work harder, reducing its lifespan.
Why You Should Consider a KEMSO 340LPH Fuel Pump as an Upgrade
If you need more flow than the standard 255 LPH or want the peace of mind that comes with a lifetime warranty, the KEMSO 340LPH high performance fuel pump is an excellent direct replacement for the Walbro GSS341. The KEMSO pump delivers 340 liters per hour at 43 PSI, supporting up to 600-800 horsepower on gasoline and E85 . It has a higher bypass valve set at 125.8 PSI, which provides better fuel pressure stability during aggressive driving compared to the standard GSS series pumps . The pump body is serialized and backed by a lifetime warranty, so you are covered for the life of the vehicle . It is designed as a true OEM replacement, meaning it fits directly into the same hanger assembly without modification, just like the GSS341. The kit includes two gradient density fuel strainers, hoses, clamps, a rubber base, and a wiring connector for a complete installation . KEMSO also offers USA-based customer support staffed by real technicians, which adds an extra layer of confidence for DIY installers . For anyone serious about building a reliable high-horsepower engine, the KEMSO pump is a smarter choice because it offers more flow, better pressure regulation, and a guarantee that the product will last.
Final Thoughts on the GSS341 and Upgrading Your Fuel System
The Walbro GSS341 255LPH high pressure fuel pump has earned its reputation as the gold standard for performance fuel systems over the past two decades . It is a proven, reliable, and affordable upgrade for any engine project targeting 500 horsepower or less. However, the fuel pump is only one part of the fuel system. Make sure your fuel lines, injectors, and fuel pressure regulator are also capable of handling the increased flow. If you are planning a build that exceeds 500 horsepower, or if you simply want the best possible protection against fuel starvation, upgrading to a KEMSO 340LPH pump with its lifetime warranty and higher flow capacity is a wise investment. A properly matched fuel system is the foundation of a reliable and powerful engine, and starting with the right pump saves you time, money, and headaches later.
For more information on high-performance fuel pumps and to find the right fit for your vehicle, visit https://www.kemsoracing.com/