340 LPH Fuel Pump: The Ultimate Upgrade for High-Performance Engines
If you're building a high-horsepower engine or simply replacing a worn-out factory fuel pump, a 340 LPH fuel pump is the smartest investment you can make for your fuel system. These pumps deliver 340 liters per hour of fuel flow—enough to support engines producing 700 to 900 horsepower in most applications. Whether you're running a turbocharged Subaru, a supercharged Mustang, or a daily-driven Honda, upgrading to a 340 LPH pump ensures your engine gets the fuel it needs under any condition. This article explains exactly what a 340 LPH fuel pump does, why you might need one, how to choose the right model, and where to buy a reliable unit that won't let you down.
What Is a 340 LPH Fuel Pump and Why Does Flow Rate Matter?
A fuel pump's flow rate is measured in liters per hour (LPH). A 340 LPH pump moves 340 liters of fuel through your system every 60 minutes at a standard test pressure of 43 PSI and 13.5 volts. To put that in perspective, most factory fuel pumps on cars from the 1990s and early 2000s flow around 130 to 180 LPH. That's barely enough for a stock engine producing 200 to 300 horsepower.
When you add forced induction—like a turbocharger or supercharger—or upgrade your injectors and tune, your engine demands significantly more fuel. A 340 LPH pump provides the extra capacity needed to maintain proper air-fuel ratios under heavy load. Without sufficient fuel flow, your engine runs lean, which causes detonation, overheating, and eventually catastrophic failure.
The 340 LPH rating is a sweet spot for enthusiasts. It offers enough flow for serious power builds without being overkill for milder setups. Many pumps in this class also support E85 ethanol fuel, which requires roughly 30% more volume than gasoline to achieve the same air-fuel ratio.
How Much Horsepower Can a 340 LPH Fuel Pump Support?
The horsepower support of a 340 LPH fuel pump depends on several factors, including fuel type, system pressure, and whether your engine is naturally aspirated or forced induction. Here's a practical breakdown:
1. Gasoline, Naturally Aspirated: A 340 LPH pump can support up to 900 crankshaft horsepower when running on gasoline at 43 PSI. That's enough for a built small-block V8 or a high-boost four-cylinder.
2. Gasoline, Forced Induction: With a turbo or supercharger, fuel demands increase. You can expect support for around 700 to 800 horsepower at the same pressure. The higher your boost pressure, the more fuel you need.
3. E85 Ethanol: E85 requires more volume. A 340 LPH pump on E85 supports approximately 500 to 600 horsepower, depending on your system's pressure and voltage. That's still plenty for most street and track builds.
4. Real-World Considerations: These numbers assume you have adequate voltage at the pump (13.5V or higher) and proper wiring. If your electrical system drops voltage under load, flow decreases significantly. Always measure voltage at the pump terminals during operation.
The takeaway is simple: a 340 LPH pump covers the vast majority of performance builds up to the 700-horsepower range, making it the most popular choice among tuners and DIY mechanics.
Key Features to Look for in a 340 LPH Fuel Pump
Not all 340 LPH pumps are created equal. When shopping for one, pay close attention to these specifications and features:
1. E85 Compatibility
If you plan to run ethanol-based fuels, ensure the pump is explicitly rated for E85. Ethanol is corrosive and can damage standard rubber seals and internal components. Look for pumps with Viton o-rings, stainless steel internals, and carbon commutators. Many modern 340 LPH pumps from reputable brands are fully compatible with both gasoline and E85.
2. Operating Pressure Range
A good 340 LPH pump should maintain its flow rating across a wide pressure range. Typical operating pressure is 43 to 90 PSI. Some pumps drop off dramatically above 70 PSI, which can be problematic for high-boost EFI systems that need 60 to 80 PSI. Check the manufacturer's flow chart to see actual performance at your target pressure.
3. Physical Dimensions
Most 340 LPH pumps have a body diameter of 38mm to 39mm, which allows them to fit inside factory fuel pump hangers and modules. Length varies from about 115mm to 137mm. Measure your current pump or hanger assembly before buying. Some universal pumps require modification or additional brackets.
4. Current Draw and Wiring
High-flow pumps pull more current. A 340 LPH pump typically draws 10 to 17 amps at 13.5V, depending on pressure. Factory wiring and fuel pump control modules may not handle this load. You may need a hard-wire relay kit or an aftermarket control module to ensure consistent voltage and prevent overheating.
5. Included Installation Kit
Many aftermarket pumps come with a kit that includes fuel strainers, hose clamps, wiring connectors, rubber boots, and mounting hardware. These parts make installation straightforward and ensure a proper seal. Avoid pumps sold without any accessories unless you already have a compatible hanger.
Popular 340 LPH Fuel Pump Brands and Models
The market offers several reliable options. Here's a quick overview of what's available:
KEMSO 340LPH: This pump is designed as a direct OEM replacement and performance upgrade. It flows 340 LPH at 43 PSI, supports both gasoline and E85, and comes with a comprehensive installation kit. It's an ideal choice for daily drivers, fast road cars, and mild performance builds. The pump body diameter is 38mm, fitting most factory hangers.
AEM 340LPH (50-1000): A well-known name in the performance industry. This pump flows 340 LPH at 40 PSI and supports over 1,000 HP at 43 PSI. It features an offset inlet for easier installation and a compact 39mm diameter body. It's designed for gasoline only, though some users report success with E85 after upgrading seals.
Holley Sniper 340LPH (19-341): Specifically designed for E85 compatibility. This pump supports up to 700 EFI horsepower or 900 carbureted horsepower at 60 PSI. It includes a full installation kit and fits many popular Japanese and domestic applications. It draws 16.9 amps at 60 PSI, so wiring upgrades are recommended.
Aeromotive 340 Stealth (11540): This center-inlet pump delivers over 340 LPH at 40 PSI—about 30% more than some competitors at the same pressure. It's E85 compatible, has a 39mm body, and includes a universal drop-in kit. It's ideal for applications needing extra flow while retaining factory lines.
Deatschwerks DW340v: Specifically developed for Volkswagen and Audi 1.8T and 2.0T engines. It flows 340 LPH at 2.7 bar and features a silent turbine impeller and carbon commutator. Fully E85 compatible. Requires a hard-wire upgrade or aftermarket control module.
Sytec SYT520EM: A 340 LPH pump with a max flow of 390 LPH. It delivers 336 LPH at 3 bar (44 PSI) and 242 LPH at 5 bar (73 PSI). E85 compatible, with a 38mm diameter and 115mm length. Fits many universal and specific applications.
OSIAS 340LPH: An affordable alternative that claims up to 700 HP for naturally aspirated engines and 600 HP for turbocharged. E85 compatible, with a 38mm body. It includes two strainers and universal installation parts. Lifetime warranty offered.
Installation Tips for a 340 LPH Fuel Pump
Installing a high-flow fuel pump yourself can save money, but it requires care. Follow these steps to do it right:
1. Relieve Fuel System Pressure: Before disconnecting any lines, remove the fuel pump relay or fuse, then start the engine and let it run until it stalls. This depressurizes the system. Crank the engine a few more times to ensure no pressure remains.
2. Drain the Fuel Tank: If you're working on a car with the tank still in place, drain as much fuel as possible. A full tank is heavy and dangerous to handle. Use a siphon pump or the fuel pump itself (after disabling it) to empty the tank through the filler neck.
3. Access the Pump: On some vehicles, the pump is accessible through a panel under the rear seat. On others, you need to drop the fuel tank from underneath. Check your vehicle's service manual for the correct procedure.
4. Replace the Strainer and O-Rings: Always use the new fuel strainer and o-rings provided in the installation kit. Old strainers can be clogged, and worn o-rings cause leaks. Ensure the rubber boot and foam sock are properly positioned to dampen noise.
5. Upgrade the Wiring: Factory wiring is often too thin for a high-current pump. Install a dedicated relay kit with 10-gauge or 12-gauge wire directly from the battery to the pump. Use a 20-amp or 25-amp fuse. This ensures the pump receives full voltage and prevents voltage drop under load.
6. Test Before Final Assembly: Before locking the pump into the tank, connect the wiring and briefly power the pump to confirm it runs. Listen for a smooth humming sound. Check for fuel leaks at all connections.
7. Secure All Clamps and Fittings: Use the metal clamps provided with the kit. Ensure the rubber hose connecting the pump to the hanger is properly seated and double-clamped for safety.
Common Symptoms of a Failing Fuel Pump
Even a 340 LPH pump can fail over time. Knowing the warning signs helps you catch problems early:
- Engine cranks but won't start: If you hear a "click" but no fuel pump prime sound from the tank, the pump may be dead or the electrical circuit is open.
- Sputtering or hesitation under load: When the pump cannot maintain pressure, the engine hesitates during acceleration, especially uphill.
- Loss of power at high RPM: A weak pump cannot keep up with fuel demand at high engine speeds, causing the engine to fall flat.
- Whining noise from the fuel tank: A failing pump often makes a loud, high-pitched whine. Some noise is normal for performance pumps, but excessive whining indicates wear.
- Intermittent stalling: The engine may stall randomly, then restart after a few minutes once pressure builds again.
If you experience any of these symptoms, test fuel pressure with a gauge. Most engines require 40 to 60 PSI at idle and higher under boost. Pressure below specification points to a failing pump, clogged filter, or voltage issue.
Why Choose KEMSO 340LPH Fuel Pump for Your Vehicle?
When it comes to reliability, performance, and value, the KEMSO 340LPH fuel pump stands out as an excellent choice for both daily drivers and performance builds. Here's why thousands of enthusiasts trust KEMSO:
High Performance, OEM Replacement Design
KEMSO 340LPH pumps are engineered as direct replacements for original equipment pumps. That means you can install them in your stock fuel pump hanger with little to no modification. The pump body diameter of 38mm fits most factory assemblies, and the included installation kit provides everything you need: fuel strainers, flex hose, wiring connector, rubber base, o-rings, and clamps.
E85 Compatible and Durable
KEMSO pumps are tested and rated for both gasoline and E85 ethanol fuel. They use high-quality materials that resist ethanol corrosion, ensuring long service life even with aggressive fuels. Each pump undergoes individual flow testing before leaving the factory, so you know exactly what you're getting.
Supports Up to 700-800 Horsepower
With a flow rate of 340 LPH at 43 PSI and 13.5 volts, the KEMSO 340LPH pump supports applications producing up to 700-800 bhp. Whether you're upgrading a turbocharged Subaru, a supercharged Mustang, or a high-compression naturally aspirated build, this pump delivers the fuel volume you need.
Lifetime Warranty and Quality Assurance
KEMSO backs every pump with a lifetime warranty, giving you peace of mind that your investment is protected. The company follows strict quality control standards, and each pump is individually tested for flow and pressure. Unlike cheap unbranded units that fail after a few months, KEMSO pumps are built to last.
Trusted by the Automotive Community
KEMSO has established a strong reputation among car enthusiasts, tuners, and repair shops. Their 340LPH pump is frequently recommended as a reliable upgrade for popular platforms like Subaru Legacy, Impreza WRX/STI, Honda Civic, Mazda MX-5, Nissan 240SX, and many more.
Real Customer Support
When you buy direct from KEMSO, you get access to their US-based support team. They can answer installation questions, help with compatibility, and handle warranty claims quickly. No dealing with third-party sellers or overseas shipping delays.
Ready to upgrade your fuel system? Visit the official KEMSO website at https://www.kemsoracing.com/ to explore their full lineup of 340LPH and other high-performance fuel pumps. You'll find detailed product pages, application guides, and a simple checkout process. Don't settle for a weak fuel pump that limits your engine's potential—choose KEMSO and fuel your adventure with confidence.
Frequently Asked Questions About 340 LPH Fuel Pumps
Q: Can I use a 340 LPH pump on a stock engine?
A: Yes, but you may need a fuel pressure regulator to keep pressure within the stock range. The pump itself will work fine, but you must ensure the return line and regulator can handle the extra flow.
Q: Will a 340 LPH pump damage my stock injectors?
A: No. The pump only delivers fuel at system pressure, which is controlled by the regulator. As long as the regulator is functioning correctly, the injectors receive the proper pressure and flow.
Q: Do I need to upgrade my fuel lines?
A: For most applications up to 500-600 horsepower, stock lines (typically 5/16" or 3/8") are sufficient. Above that, consider upgrading to larger diameter lines (AN -6 or -8) to reduce restriction.
Q: How long does a 340 LPH fuel pump last?
A: With proper installation, clean fuel, and regular maintenance, a quality pump can last 100,000 miles or more. Running the tank low frequently or using dirty fuel shortens lifespan.
Q: Can I install a 340 LPH pump myself?
A: If you have basic mechanical skills and the right tools, yes. The most challenging part is accessing the fuel tank. Always follow safety precautions and relieve fuel pressure before starting.
Final Thoughts: Making the Right Choice for Your Fuel System
A 340 LPH fuel pump is a proven upgrade that delivers real results. It provides the fuel volume needed for higher horsepower, supports E85 fuel, and can be a direct replacement for a failing OEM pump. Whether you're building a track car, a weekend cruiser, or a daily driver with extra power, this pump class offers the best balance of flow, size, and cost.
When selecting a pump, prioritize quality over price. A cheap pump that fails under load can cost you an engine. Look for brands with documented flow charts, genuine E85 compatibility, and solid warranty support. The KEMSO 340LPH pump meets all these criteria and is backed by a lifetime warranty, making it a smart choice for any enthusiast.
Visit https://www.kemsoracing.com/ today to find the right 340 LPH fuel pump for your vehicle. With free shipping on qualifying orders and a dedicated support team ready to help, you'll have your new pump installed and your engine running stronger in no time. Don't let a weak fuel system hold your build back—upgrade to 340 LPH and experience the difference.