OK i need to know what my best option is. I have 2 walbros in parelle and i was planing on running a 8 feed and y it into 2 -8 to each rail. But than i was thinking that those 2 -8s will need more fuel, i think?? SO should i run a 10 feed to 2 -8s? Or should i run it in series with just straight -8?? But i have heard that series isnt the best way of runing it. Anyone have any advice for me? thanks
Marc

 

I am running a -10 feed into a Y-block with two -8 lines running the rails in parallel with a -8 return. I don't know anywhere near enough about fuel systems to answer your questions....I am just telling you what I did. My basis for this was that a -10 fuel line split into two -8 fuel lines made more sense to me than a -8 line split into two -8 lines. If that helps, great, if not, oh well, I am just letting you know what I did.

 

I did the -10 Feed into the Y Block in the Engine bay, then two -8 to my rails.

 

Well thanks for letting me know your setups i decided on the same thing.. But i have a questoin for you guys do you have a fuel pressure gauge, it seems like a single -10 wouldnt flow enough for 2 -8s cause thats -16. Am i thinking right?? IM not saying get -16 feed but dosent that amke more sense. so if i ran a -10 than then the most you can flow to each rail is a -5, since they dont make a -5 as far as i know you would want to go bigger and get the -6. But -8 seems like you wont have a chance in hell to fill each of the those line with a -10. Am i thinking in the correct terms??
thanks
marc

 

Also i have Keiths rail whcih i would recommend.... they are taped for 3/8th and 3/8th is about -6 so dosent that make sense that you would want to split them into 6s. Dose it matter if you use -8s and they are to big, that seems like it would be a probem as the line is not fully presure.. Thanks
Marc

 

I would guess that the fuel lines are measured much like wires in terms of guages... So a bigger fuel line would be proportionally bigger than the step below it, not linearly. (NOT SURE ... just a guess.) -JinX

 

marc i think you are thinking way to into it. these are not garden hoses with no attatchments on the ends.... you have a fuel pressure regulator. this helps you wile trying to up the presure in the line. i would say that you should use the -10 delivery split into 2 -8's. but that is just my opinion.

 

not correct with fuel lines.

 

marc, also take a look at the inside diameter of the rails. i know they are tapped for 3/8NPT, but compare that to the inside diameter of a -6 fuel line.

 

Nope! The AN dash number is related to diameter, so 2 -8 lines would be about the same as 1 -11 line if that existed. But a -10 will be okay, unless you're doing something REALLY wild.

 

OK thanks for setting me straight! -JinX

 

I think inhave decided on feed -8 and splitting it to 2 -8 to each rail! Im almost set on this. Eggie i dont understand your math there would you mind explain it. SO the diameter is 2 -8AN so to flow enough to that seem like a -16 would be enough. Or is it because of the FPR that keeps the pressure in those line? Keith i enjoy causeing myself pain!! My life isnt stress out enough so ill put some extra worrin into this!
thanks for the help.

 

Schools today!

As I said, the dash number is related to the diameter. It's by 16ths of an inch, so -8 is 1/2" line. Since A = Pi * R ^ 2, a single -8 line is 0.785 square inches. For a single line to provide twice this area, it would calculate out to AN-11.3. But that's not a real size...

You with me?

 

These threads always crack me up. You guys and your sewer pipe fuel lines.

To that last post, the internal area of a -8 line is .1963 sq in not .785 but you did get the 11.3 part right.

 

Yep a first no i didnt get it, than the correction i got it! IM just gonna run -8 feeed split into 2 -8s because the smallest part of the system is the 3/8th rail dia. so no point in going bigger than 1/2 split on the rail or -8.
thanks
Marc

 

Why not run a -8 to the "Y" then -6 to each rail? -6 is a lot easier to bend around than -8.

I did a pressure drop test on my fuel system, installed the gauge at the pump (mounted at rear of car). With my bosch fuel pump and -6 line all the way to the fuel rail including filter and it came up at 2 psi! 2psi is nothing. I think the mojority of the people on this forum go way overkill on line sizes for their fuel systems. Remember, the larger the line the more stress it puts on the fuel pump when accelerating hard. Thants a large column of fuel pushing back on the pump.

 

I heard a romor that Ari runs stock lines in his car?? I cant see how this would be true!! So if it was those -6 feed you be enough!

 

I believe the stock lines to and from the tank are 3/8 or more or less the same size as a -6 so you would only need to replace the rubber lines to and from the rails in the engine bay with SS line, the factory hardlines below the car are more or less the same size as a -6 AN. I think....don't quote me here, I may be wrong, but the I/D are the same I think.

I have no idea what Ari runs for lines, but I highyl doubt that he runs the stock hard lines, not with his setup and boost level....more boost = more fuel/more air...so I can't see the stock lines working out.

I never wanted to redo my fuel lines again....so I went as big as I think I will ever need. Hence the "sewer pipe" fuel lines. -10 feed, -8 return, A1000 pump

 

Schools when I was in school!

Dunno HTH I used the diameter instead of the radius to calc area, but it was definitely off by 4x. Good catch, setzep

 

A circle has 78.54% the area of a square with the same dimensions. Maybe thats how you did your math.

 

i was making around 500rwhp on your dynos with a stock 1st gen fuel rail, and its about 5/16", i have just put a 3/8 line on there and am looking for about 620rwhp with this setup

 

OMG that is funny....


Shawn

 

Setzep,

You are smart! Did the same setup on a car. Having and extra 'foot' of fuel by feeding to the front of the engine and return in the back of the rails, too. If more people did the math, they would see that AN-08 split to AN-06 is more than enough for 700+ HP.

Tony

 

why?

 

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