Automakers Upgrade Fuel Lines for Better Engine Efficiency

Imagine your high-performance engine craving explosive power, but being unable to fully unleash its potential because its "veins" are too narrow. Selecting the proper fuel line size is like choosing the right vascular system for your engine—it ensures adequate fuel delivery to unlock peak performance. This practical guide will help you avoid fuel starvation and keep your engine upgrade path running smoothly.

For performance-oriented vehicle owners, every detail of the fuel system is critical. While the fuel pump serves as the heart of the system—transporting fuel from tank to engine—even the most powerful pump can be hamstrung by undersized fuel lines. This restriction creates an artificial bottleneck, leaving your engine "hungry" and unable to perform at its best. This becomes particularly important with external fuel pumps, which primarily push rather than pull fuel.

Many aftermarket fuel pumps specify their required fuel line size. If your pump lacks this information, use these horsepower-based recommendations for lines running from tank to fuel pump:

• 350 HP or less: 5/16 inch (-5 AN)
• 350-450 HP: 3/8 inch (-6 AN)
• 450-650 HP: 1/2 inch (-8 AN)
• 650-1,000 HP: 5/8 inch (-10 AN)

Beyond horsepower output, several factors influence fuel system efficiency:

• Pump placement: Position external fuel pumps close to and below the tank outlet to utilize gravity assistance. Remember: external pumps push better than they pull.
• Filtration: Always install a 100-micron inline fuel filter between tank and pump to protect against contaminants.
• Line reduction: Post-pump lines can be slightly smaller, but must still meet engine demands.
• Alternative fuels: E85, alcohol, or methanol require one size larger fuel lines to accommodate their greater volume needs.
• AN hose advantages: The corrosion-resistant, high-pressure capabilities of AN hose make it ideal for performance fuel systems.

A complete fuel system overhaul often includes these components for balanced performance:

• Carburetors & accessories: Properly sized carburetors with appropriate accessories ensure optimal fuel atomization.
• Fuel tanks: Upgrade to larger capacity or lightweight tanks when needed.
• Pumps & regulators: High-performance units maintain consistent fuel pressure and volume.
• Pre-packaged kits: Complete fuel line kits simplify installation while ensuring compatibility.
• Supporting components: Air filters, intake manifolds, and other supporting parts complete the performance package.

Proper fuel line sizing forms the foundation of any successful engine upgrade. By matching line size to your horsepower goals and fuel type—while considering pump placement and filtration—you'll create a system that delivers consistent performance whether on the track or the street.