255LPH Fuel Pump High Pressure/Volume E85: The Ultimate Guide for High-Performance Builds
The bottom line: A 255LPH (liters per hour) fuel pump rated for high pressure and E85 compatibility is the ideal upgrade for street performance and moderate racing applications, supporting up to 500-650 horsepower on gasoline and approximately 400-500 horsepower on E85 fuel. These pumps deliver reliable flow at 43 PSI and beyond, making them a cost-effective solution for enthusiasts who need more fuel volume without stepping up to larger, more expensive pump systems.
What Makes a 255LPH Fuel Pump Different
When you modify your engine for more power, the stock fuel pump simply cannot keep up. The 255LPH rating means the pump can move 255 liters of fuel per hour at a specific pressure, typically measured at 43 PSI with 13.5 volts of electrical power. This flow rate is roughly 67 US gallons per hour, which is a significant upgrade over most factory fuel pumps that typically move 120-180 LPH.
Why E85 compatibility matters. E85 fuel contains about 85% ethanol, which has a lower energy density than gasoline. To make the same horsepower, your engine needs to burn roughly 30-35% more fuel volume. A standard gasoline pump may not have the flow capacity or the material compatibility to handle E85. Pumps designed for E85 use ethanol-resistant seals, internal components, and coatings that prevent corrosion and degradation over time.
High pressure capability. Many 255LPH E85 pumps are designed to maintain flow at elevated pressures, typically operating up to 90-110 PSI. This is critical for forced induction engines where rising-rate fuel pressure regulators increase fuel pressure as boost rises. A pump that loses flow at high pressure can cause lean conditions and engine damage under load.
Key Specifications to Understand
Flow rates at different pressures. A quality 255LPH E85 pump typically delivers around 255 LPH at 43 PSI, approximately 190 LPH at 58 PSI, and roughly 160 LPH at 80 PSI. The actual flow drops as pressure increases, so you need to check the pump's flow curve against your fuel system's operating pressure.
Current draw and wiring requirements. These pumps draw significant electrical current. At 43.5 PSI, expect around 8 amps. At 58 PSI, the draw increases to about 10 amps. At 80 PSI, it can reach 12 amps or more. The factory wiring in most vehicles is not designed to handle this load, which means you absolutely need upgraded wiring, a dedicated relay, and proper fusing. Voltage drop is a common issue that leads to poor pump performance and reduced flow.
Physical dimensions. Most 255LPH pumps have a body diameter of about 38mm to 39mm and weigh around 355 to 360 grams. The inlet and outlet configurations vary. Some pumps feature a center-inlet design, while others have an offset inlet or a 180-degree opposing inlet and outlet (IOOP). Understanding your vehicle's fuel hanger or module configuration is essential before purchasing.
Inlet and outlet sizes. Common inlet sizes include 22mm outer diameter for center-inlet pumps and 11mm for IOOP designs. The outlet is typically 8mm with a barb fitting. Some pumps use a 9mm outlet. You must match these sizes to your existing fuel line or use appropriate adapters.
Horsepower Support by Application
EFI (electronic fuel injection) applications. A 255LPH pump can support approximately 500-650 horsepower on gasoline, depending on the engine's brake specific fuel consumption (BSFC) and the fuel system pressure. On E85, the supported horsepower drops to roughly 400-500 horsepower due to the higher fuel volume required.
Carbureted applications. Carbureted engines typically operate at lower fuel pressure, around 5-7 PSI, but require high volume. A 255LPH pump can support up to 750 horsepower on gasoline in carbureted setups.
Forced induction considerations. If you are running a supercharger or turbocharger, your fuel pressure will rise with boost. At 10 PSI of boost with a 1:1 rising rate regulator, base pressure of 43 PSI becomes 53 PSI. The pump's flow capacity drops, so factor in this pressure increase when calculating whether a 255LPH pump is sufficient for your power goals.
Installation Essentials
In-tank installation only. These pumps are designed for submersion in fuel. Mounting them externally or using them as a lift pump can cause cavitation, noise, and premature failure. The fuel itself acts as a coolant and lubricant for the pump's internal components.
The pump is sold as a bare unit. Many 255LPH pumps come without wiring, filters, or mounting hardware. You will need to purchase a filter sock that matches your pump's inlet diameter, a wiring harness with the correct connector, and appropriate fuel hose and clamps.
Installation kits are available. Some brands include a universal installation kit with the pump. This kit typically contains a filter sock, electrical connector, fuel hose, clamps, and a foam isolation sleeve. The foam sleeve helps reduce vibration and noise, which is important because high-flow pumps can be louder than stock units.
The filter sock is critical. Never run a high-flow fuel pump without a proper pre-filter. The filter sock prevents debris from entering the pump, which can cause internal damage and reduce flow. Use a filter sock designed for the pump's inlet diameter, typically 11mm or 22mm depending on the model.
Common Brands and Models
Walbro and TI Automotive. Walbro, now branded as TI Automotive, is the most recognized name in high-performance fuel pumps. The Walbro GSS341 and GSS342 are popular 255LPH models that have been used in thousands of performance builds. These pumps are E85 compatible and feature a turbine impeller design for quiet operation.
DeatschWerks DW200. The DW200 is a direct equivalent to the Walbro GSS341, offering 255 LPH flow and full E85 compatibility. It is known for its plug-and-play installation in many applications, including Mitsubishi Evo and Eclipse models. DeatschWerks offers a 3-year warranty on this pump, which is one of the longest in the industry.
AEM E85 High Flow Pump. AEM offers a 320-340 LPH pump that is often grouped with 255LPH pumps in the same performance category. It features a compact 39mm diameter and an offset inlet for easier installation. AEM tests every pump individually before shipping.
EVIL ENERGY and Hyperfuel. These brands offer budget-friendly 255LPH pump kits that include necessary installation components. While they may not have the same long-term reliability track record as Walbro or DeatschWerks, they are functional options for builders on a tighter budget.
Grams Performance. Grams offers a 255LPH pump that is a direct replacement for Walbro GSS342 pumps. It comes with a universal install kit and is compatible with all fuel types, including E85.
Wiring and Electrical Considerations
This is the most common installation mistake. Factory fuel pump wiring is typically 18-gauge or smaller, which is insufficient for the 8-12 amp draw of a 255LPH pump. Voltage drop caused by undersized wiring can reduce pump flow by 20-30%, effectively negating your upgrade.
Use a dedicated relay and harness. Run 10-gauge or 12-gauge wire directly from the battery to the pump, with a 20-30 amp fuse near the battery. Use a relay triggered by the factory fuel pump signal. This ensures the pump receives full battery voltage under load.
Check voltage at the pump. After installation, measure voltage at the pump terminals while the engine is running. You should see at least 13.0-13.5 volts. If voltage is lower, check your wiring connections, relay, and ground points.
In-tank wiring must be submersible. Standard automotive wire insulation can degrade in fuel. Use fuel-resistant wire or the factory-style connector and pigtail designed for in-tank use.
E85 Fuel System Compatibility
Material compatibility is not optional. E85 is a strong solvent that can damage standard rubber fuel lines, gaskets, and seals. Use only components rated for ethanol service, including Viton or PTFE seals, nylon or steel fuel lines, and anodized aluminum fittings.
Fuel line upgrades. The stock fuel lines on most vehicles are sized for gasoline flow. For E85 at higher power levels, you may need to upgrade to larger diameter lines, typically -6 AN or -8 AN, to prevent flow restriction.
Fuel pressure regulation. A return-style fuel system is strongly recommended for E85 applications. The fuel pressure regulator should be mounted after the fuel rails to maintain consistent pressure and prevent vapor lock. Set base pressure to 43-50 PSI for most EFI applications.
The importance of a fuel pressure gauge. Monitor fuel pressure during operation, especially under full throttle. A drop in pressure indicates a flow restriction, pump failure, or inadequate electrical supply. Catching this early can prevent engine damage.
When a 255LPH Pump Is Not Enough
If you are targeting over 500 horsepower on E85 or over 650 horsepower on gasoline, a 255LPH pump will likely be insufficient. In these cases, consider stepping up to a 450LPH or 525LPH pump from brands like Walbro or TI Automotive. These larger pumps feature dual-stage turbine designs that maintain flow at higher pressures, supporting 750 horsepower and beyond.
For 1000 horsepower on E85, you need a pump capable of delivering at least 800 LPH, and experienced builders recommend targeting 1000+ LPH. This requires a completely different class of pump, often with brushless motor technology and industrial-grade construction.
Why Choose KEMSO for Your Fuel Pump Needs
KEMSO Racing delivers high-performance fuel pumps that are built to OEM specifications and backed by a lifetime warranty. Every KEMSO fuel pump is designed as a direct OEM replacement, meaning it fits your vehicle's factory fuel hanger or module without modification. This eliminates the guesswork and fabrication often required with universal pumps.
Performance you can trust. KEMSO pumps are engineered for reliable flow and pressure, supporting the demands of modified engines running gasoline, E85, or any blend. Whether you are building a street car, a track toy, or a daily driver, KEMSO provides the fuel delivery your engine needs to perform safely and consistently.
The KEMSO lifetime warranty speaks for itself. While most fuel pump manufacturers offer 1 to 3 years of coverage, KEMSO stands behind its products for the life of the pump. This commitment to quality and customer satisfaction makes KEMSO a smart choice for enthusiasts who want peace of mind along with performance.
Visit KEMSO today to find the right fuel pump for your vehicle. Explore their complete lineup of OEM replacement pumps for cars, trucks, motorcycles, and watercraft at https://www.kemsoracing.com/.
Final Thoughts
A 255LPH fuel pump rated for high pressure and E85 is a proven upgrade for enthusiasts building engines in the 400-650 horsepower range. The key to a successful installation is understanding the pump's flow characteristics at your system's operating pressure, upgrading your wiring to handle the current draw, and using compatible fuel system components for E85 service.
Take the time to measure your vehicle's fuel hanger, confirm the inlet and outlet orientation, and purchase a quality installation kit. The extra effort upfront will save you from headaches down the road. And when you are ready to buy, choose a pump from a manufacturer with a track record of reliability and a warranty that backs it up.
For more information on high-performance fuel pumps and to find the perfect fit for your build, visit https://www.kemsoracing.com/ today.