Sizing and Power Considerations for Fuel Systems

At some point you may wish to connect your factory fuel lines to an aftermarket fuel rail, and/or fuel pressure regulator. While one option is to eliminate the factory lines all together, this is generally unnecessary unless factory lines are heavily corroded or horsepower goals grossly exceed what the factory hard line can accommodate. In most instances, a drop-in fuel pump to the factory tank retaining the factory line is more than sufficient.

If, at a later time, you decide to drastically change your build, you can always replace the factory line segment independently of the engine bay segment of line with a simple union fitting.

Refer to our table for line diameters and post-pump feed-line AN sizing appropriate for various power goals. Note that this is merely a rule of thumb, and many other factors exist, including fuel type and pump configurations that may warrant actual consumption and operating pressure calculation and are beyond the scope of this article.

If you decide to replace the factory line instead of retaining it, stepping up in AN size now to give yourself head room and margin for future expandability nominally impacts cost; but would be expensive to replace in its entirety should your build change drastically.