i have 1/4 I.D. Fuel lines on my dart and am adding a 150 shot of nitrous do I need to upgrade my fuel lines from tank to fuel pump? Mild built 360 with a 750 cfm carb and air gap intake. How much horsepower will my fuel lines support?

Zero. You need to do some more homework.

It obviously supports some horsepower it's factory type replacement and I have had it on my car for four years now. Do I need to upgrade is my question? Asking questions on here is doing homework ... I thought?

Hoping its a wet kit, but there's no way I'd rely on that size with a decent displacement small block and nitrous. A lack of fuel when on spray will scatter that engine faster than just about anything else.

Fuel line is not where you should save money. You will be close to the threshold of "not enough" when on the button, and the consequences will be detrimental if you cross that line.

Depends on your fuel pump. If you have a good pump in the rear of the car you can push a lot of fuel thru a 1/4 line. If you have a mechanical pump on the engine that is pulling fuel thru the line then you'll be limited.

Thanks guys I do have a Holley black pump but it sounds like I better upgrade my fuel line. Thanks again.

Notice he said 1/4" ID for his tubing, and tubing is named by the OD, so he has the same 5/16 line that 98% of factory musclecars had. Not exactly a zero-power setup, as someone has suggested...

Sorry it is 5/16 o.d and 1/4 i.d I didn't know what dimension was needed

The suction side of the pump is most important so the pump is well fed and does not cavitate at higher flows rates.

The factory upgraded to 3/8" for Hemi's... basically north of 400 HP. I would suggest 3/8" minimum from the fuel tank to pump (including pickup) and 3/8" after that with the NOS.

3/8" OD line/sender from the tank to the pump inlet and 5/16" OD from outlet to the carb will be more than enough for what a 360 (even on the juice) is going to need.

If a 426 HEMI can sing with this, than he should be fine.