What Size Fuel Line Do You Need? Fuel Line Sizing by Horsepower
The Partsman
Fuel line that is too small starves your engine; too big can hurt return-line pressure and cost you money. Here is how to get it right.
Quick fuel line size guide
| Power (petrol) | Feed line | Return |
|---|---|---|
| Up to ~300 hp | -6 AN | -6 AN |
| ~300-500 hp | -8 AN | -6 AN |
| ~500-700 hp | -8/-10 AN | -6/-8 AN |
| 700 hp+ | -10 AN | -8 AN |
Running E85 or methanol? Step up roughly one size - these fuels need more volume for the same power.
Feed vs return
The feed line carries fuel to the rail and does the hard work, so size it for your power goal. The return can usually be one size smaller. On returnless/EFI setups, follow your pump and regulator recommendations.
Hose type matters too
For pump petrol a quality push-lock or 100-series braided hose is fine. For E85, methanol or PTFE applications use PTFE (Teflon) hose - it resists modern fuels and won't weep odour.
Don't forget fittings
Match your hose to the right AN hose ends and adapters, and check the thread on your pump, filter and regulator.
Not sure what your build needs? Call The Partsman on 07 846 1923 or browse fuel system parts. We can build lines to length too.
