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Fuel Line basics and sizing

Fuel Gas Line AN Line Ethonal Alcohol Methanol E85 Safe Hose Rubber

Also precautions for Ethanol/alcohol/methanol based fuels

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The sizing of fuel lines is VERY IMPORTANT to those that are starting to push the limits of power on there cars or trucks. Understanding then how to size the supply and return line will be good information to know.

Sizing Supply and Return Lines Properly

For most applications the factory fuel lines have been able to support around 500 whp. There are variations to this based on each vehicle and the fuel being used. For example if using E85, which requires 30% more fuel to reach stoic conditions, you would need to size the fuel lines even larger. If unfamiliar with ethanol based fuel, be sure to check out our article here on ethanol-based fuels.

Here is a picture of Ethanol rated fuel hose.

Fuel Gas Line AN Line Ethonal Alcohol Methanol E85 Safe Hose Rubber

As a rule of thumb I would suggest the following:

Up to 500-550 whp: Stock Fuel Lines

Up to 800 whp: -8 AN supply Line; -6 AN return Line

Up to 1200 WHP: -10 AN supply Line; -8AN Return Line

OVER 1200 WHP: You are on your own. I have no experience here.

As you can see the return fuel line is always sized smaller than the supply line. The reason for this is that the return line will always flow less fuel being that the motor is using a portion of the supplied fuel to burn and run the motor.

Fuel Gas Line AN Line Ethonal Alcohol Methanol E85 Safe Hose RubberFuel Gas Line AN Line Ethonal Alcohol Methanol E85 Safe Hose Rubber

Things look for when buying fuel line

Many users today are discovering the benefits of using ethanol based fuels or methanol. While these fuels are great, not all fuel lines are rated to withstand their corrosive properties. Therefore it is important when purchasing fuel lines that you are realistic with the fuels you MAY end up running in your vehicle. I would suggest to plan for all options, and select a fuel line that is alcohol/methanol/ethanol rated so that there are no problems down the line. These types of fuels are VERY corrosive and will destroy fuel lines, and fuel cells that are not rated to handle them. You may not even know its doing damage till its to late. Often what occurs is the fuel line gets deteriorated from the inside and small chunks of rubber are released. These contaminants can now clog fuel filters or worse, clog an injector causing a cylinder to run lean until detonation and damage has occurred.


How many times have we done a modification to our car only to get the itch again for more power? Remember this itch when sizing your fuel lines. Always give yourself some breathing room and be realistic with you goals. Planning ahead will save you HUGE headaches in this department.


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