When you planned your car’s fuel system, how much thought did you give to fuel line size, and how it affects fuel pressure drop? It’s safe to say, many of you didn’t. You simply mount your pump, filter, and regulator, and run the lines. You then set the pressure, and let it fly. In many cases, that’s totally fine, and you’ll probably be okay. However, since when did you want to rely on “probably” when it comes to your race car? Probably never, right?!
Thankfully, Fuelab has done some research on pressure drop. Here’s the full article, but we offer you this quick synopsis for people with short attention spans.
So let’s look at what causes pressure drop. Fuelab tells us there are three primary causes; fuel line size, fuel line length, and flow rate. But all three of these causes center around one primary issue, and that’s friction the fuel undergoes while traveling through fuel lines, fittings, and hoses.
During Fuelab’s analysis, it was found that the longer the fuel line, the more friction the fuel is susceptible to. Flow rate plays a factor as well. A higher flow rate will increase friction. Something else to look at with this is fuel line size. Obviously, if you’re trying to squeeze a bunch of fuel through 3/8-inch line during heavy acceleration, you could run into a starvation issue. That’s why most of you have -10, or larger, fuel lines on your cars. Larger fuel lines will give you the capacity a hungry fuel system needs to keep up with demand.
For the normal everyday street car, these are not issues. However, with race cars that move a lot of fuel, especially during a pass, these issues are very real, and something that needs to be investigated to make sure your car is getting adequate fuel to the injectors or carburetor(s).