How to Fabricate Fuel Lines

You can calculate how much fuel your engine needs as a general rule. A normally aspirated engine will use about .5 pounds of fuel per horsepower per hour at wide-open throttle. Forced induction will be slightly higher, ranging from.6 to.75 pounds per hour. Calculate the weight of a gallon of gasoline, which is approximately 6 pounds.

For instance: 350 horsepower multiplied by.5 equals 175 pounds. 175 pounds divided by 6 equals 29 gallons per hour (GPH)

The volume and pressure connection is inversely proportional. The volume reduces as the fuel system pressure rises. Consider what your fuel delivery system requires to function, whether it’s carbureted or fuel injected. A pump rated 110 GPH with 6 to 8 psi will be more than adequate for a carbureted moderately built street engine under 450hp, for example.

How to Fabricate Fuel Lines


Fuel pressure requirements for four-barrel carbureted systems are typically between 6 and 8 psi. The gasoline system will not require a regulator if the fuel pump is rated between 6 and 8 psi. A regulator is essential when utilizing pumps with pressures of more than 8 psi to prevent the carburetor from flooding. The maximum pressure on many older carburetors, such as Stromberg and Ford type 94 carburetors, should not exceed 3psi. Anything higher than that can flood the carburetor by overpowering the needle and seat.


Most factory applications came with 5/16-inch fuel lines, but 3/8-inch (AN 6) fuel lines is a good improvement for many street vehicles and modest race applications. 1/2-inch (AN 8) fuel line will be used in high-performance applications and racers employing alcohol. Avoid utilizing rubber gasoline lines and route your lines as far away from heat sources as possible, such as exhaust. For low-pressure applications, an aluminum fuel line is ideal, but you may also use a blue and black high-pressure fuel hose or stainless steel braided hose. Remember that a 90-degree fitting adds many feet of gasoline line to the fuel system while routing the fuel line. As a result, two 45-degree fits are preferable to one 90-degree fitting when making a turn.