Help me with planning my fuel system

[mrblyoung]

You could use a stock beetle small carburetor fuel line as a return line. There's so little pressure on the return line and that little line won't cause much restriction at that point.

Yup. Thats the plan. Run a new line through the tunnel and use the original line as the return. Still determing what I am gonna do to return the return line back into the fuel system. I know the CB T that replaces the stock tank fitting is an option, but trying to find a slightly better option. I am thinking about possibly having Jeff (55superbeetle) do the little swirl pot/fuel pump on the bottom of the fuel tank. Still looking at options.

[jhoefer]

You could use a stock beetle small carburetor fuel line as a return line. There's so little pressure on the return line and that little line won't cause much restriction at that point.

The danger there, when the return line isn't the same size or larger than the supply line, is that you could potentially have problems with keeping fuel pressure down. The small return line is a restriction (just like the regulator) so if the fuel flow is above a certain point, it can cause an uncontrolled increase in fuel pressure. That is, the symptoms are you can't reduce the fuel pressure through the regulator adjustment.

[MarioVelotta]

You could use a stock beetle small carburetor fuel line as a return line. There's so little pressure on the return line and that little line won't cause much restriction at that point.

The danger there, when the return line isn't the same size or larger than the supply line, is that you could potentially have problems with keeping fuel pressure down. The small return line is a restriction (just like the regulator) so if the fuel flow is above a certain point, it can cause an uncontrolled increase in fuel pressure. That is, the symptoms are you can't reduce the fuel pressure through the regulator adjustment.

The stock fuel line as a return is perfectly acceptable. I have done just this in my own car to 250rwhp with a static fuel pressure of 60psi and had no fuel pressure issues. I am using a Walbo 255lph pump and 5/16" main feed to the back.

[andy198712]

You could use a stock beetle small carburetor fuel line as a return line. There's so little pressure on the return line and that little line won't cause much restriction at that point.

The danger there, when the return line isn't the same size or larger than the supply line, is that you could potentially have problems with keeping fuel pressure down. The small return line is a restriction (just like the regulator) so if the fuel flow is above a certain point, it can cause an uncontrolled increase in fuel pressure. That is, the symptoms are you can't reduce the fuel pressure through the regulator adjustment.

The stock fuel line as a return is perfectly acceptable. I have done just this in my own car to 250rwhp with a static fuel pressure of 60psi and had no fuel pressure issues. I am using a Walbo 255lph pump and 5/16" main feed to the back.

Does 8mm pipe slip over the 5/16th and clamp on ok? thats what i was planning...

[jhoefer]

You could use a stock beetle small carburetor fuel line as a return line. There's so little pressure on the return line and that little line won't cause much restriction at that point.

The danger there, when the return line isn't the same size or larger than the supply line, is that you could potentially have problems with keeping fuel pressure down. The small return line is a restriction (just like the regulator) so if the fuel flow is above a certain point, it can cause an uncontrolled increase in fuel pressure. That is, the symptoms are you can't reduce the fuel pressure through the regulator adjustment.

The stock fuel line as a return is perfectly acceptable. I have done just this in my own car to 250rwhp with a static fuel pressure of 60psi and had no fuel pressure issues. I am using a Walbo 255lph pump and 5/16" main feed to the back.

That's why I specifically used the word potentially. I agree with you that the chances are good that it will work just fine (and nearly guaranteed if using a known working combination of parts), but there's too many variables to assume it'll work in general for everyone 100% of the time.

[MarioVelotta]

Does 8mm pipe slip over the 5/16th and clamp on ok? thats what i was planning...

I use 7mm because it fits tighter, but 8mm works well.

That's why I specifically used the word potentially. I agree with you that the chances are good that it will work just fine (and nearly guaranteed if using a known working combination of parts), but there's too many variables to assume it'll work in general for everyone 100% of the time.

The only reason for it not to work is a plugged factory line. That's about the only variable that won't allow it to work for everyone under 300hp or running a 3/8" feed line. The fact of the matter is at that HP level the injectors are consuming a large amount of the fuel leaving even less to be returned to the tank.

[Jadewombat]

Again, there's almost no pressure after the regulator at the fuel rail but before the return line trip to the fuel tank--it's just pushing volume at that point. The smaller line "may" speed the annular velocity of the fuel going back to the tank a little, but unless the restriction were really small you're probably not going to see an increase of pressure on the fuel system, much less is it going to put an additional load on the fuel pump.

[jzsquared]

I never liked the idea of the tee on the bottom of the tank for the return so I went a different route. I purchased a AN6 bung and paid someone $10 to weld it on. It you are using the stock return line a AN4 bung would also work and you could just clamp it to the stock fuel line. The line I purchased came in a 25' role so I just ran new line to and from

[jzsquared]

One more with the tank out, overkill I know but I like it that way