-6 vs -8 fuel line (what you may not know)
03-31-2014, 07:30 AM
#1
Staging Lane
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-6 vs -8 fuel line (what you may not know) So, many folks out there on the interweb have recommended -6 fuel line for supply and return for a roughly 375 - 400 hp LS application.
Stock GM fuel line sizes are 3/8". So equivalent AN size is -6; however, I think what many folks forget or do not know is that AN sizes are OD not the ID. The ID of a -6 fuel line is less than 5/16" at .312 (Fragola hose).
I did the same thing. I am using a Walbro GPA 2 pump assembly from TANKs INC rated for up to 450HP. That assembly and the GPA 4 (rated for 650 hp) have supply and return sizes of -6 AN. The popular Corvette fuel pressure regulator and filter has the following sizes: supply @ 3/8" and return at 5/16". However, the AN adapters supplied with the kit from Speedway motors are all -6.
So, since your volume/flow is only as great as your smallest restriction, I went with -6 PTFE fuel line. I figured these companies are supplying -6 fittings in kits, so they must know what is right... I'm not too sure less than 5/16" supply line is adequate even though I'm under 450 hp.
Thoughts?
Stock GM fuel line sizes are 3/8". So equivalent AN size is -6; however, I think what many folks forget or do not know is that AN sizes are OD not the ID. The ID of a -6 fuel line is less than 5/16" at .312 (Fragola hose).
I did the same thing. I am using a Walbro GPA 2 pump assembly from TANKs INC rated for up to 450HP. That assembly and the GPA 4 (rated for 650 hp) have supply and return sizes of -6 AN. The popular Corvette fuel pressure regulator and filter has the following sizes: supply @ 3/8" and return at 5/16". However, the AN adapters supplied with the kit from Speedway motors are all -6.
So, since your volume/flow is only as great as your smallest restriction, I went with -6 PTFE fuel line. I figured these companies are supplying -6 fittings in kits, so they must know what is right... I'm not too sure less than 5/16" supply line is adequate even though I'm under 450 hp.
Thoughts?
Last edited by cgo; 03-31-2014 at 09:07 AM.
03-31-2014, 09:01 AM
#3
Staging Lane
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My Fragola PTFE 6000 series -6 line ID is .312 which is slightly under 5/16".
Looks like I'm returning it and all fittings to go with a -8 setup for supply. less than 5/16 seems too small to me. 3/8" = .375. -8 Fragola hose has an ID of .401 which is closer to the recommended 3/8" size.
Looks like I'm returning it and all fittings to go with a -8 setup for supply. less than 5/16 seems too small to me. 3/8" = .375. -8 Fragola hose has an ID of .401 which is closer to the recommended 3/8" size.
Last edited by cgo; 03-31-2014 at 09:08 AM.
03-31-2014, 12:40 PM
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Not saying to use -8 if over 450. Just looking for opinions because I was surprised that the ID of -6 is less than 5/16". If you run hard line, tube size ID is closer to what is advertised. AN sized hose and fittings are different. -6 is generally assumed to be 3/8" but the id which matters isn't 3/8".
I'll probably be fine with -6 but I only want to make up hoses once and I plan to swap in a much higher HP engine in the future so I would rather have the capacity already built in. Must swap out to a higher capacity pump and go.
I'll probably be fine with -6 but I only want to make up hoses once and I plan to swap in a much higher HP engine in the future so I would rather have the capacity already built in. Must swap out to a higher capacity pump and go.
