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5/16 fuel line vs 3/8


alejohndro5

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I ran -6 line (5/16) for quite a long time in my car. I did start to have delivery issues when I pushed the engine to about 550hp. Then I started to see some trouble. The biggest thing is to get injectors sized correctly. Pushing the fuel pressure up to 4 BAR is really a tough thing to do. Most of the pumps out there just will not provide good pressure with boost added to the mx.

 

So unless you are running some high hp numbers (well realitivity high LOL)then keep what you have. I can tell you, there are very few shops, or people who will do a good line for you. Myself, I just went to 1/2 316L seamless line. I have never had any further flow problems since.

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JeffP meant what he said, he just mis-stated the Dash Number.

He was over 500RWHP with the stock 5/16" feed, and 1/4" return line.

When he updated, it was to 1/2" (-8) Feed and 3/8" (-6) Return of 0.035" wall T304L Stainless Steel which he used my Swagelock Benders (Thank You "Cost-Plus" Contracts!) 

 

This dropped 1 Bar(G) off his static pressure at the rear of the car at maximum flow, as I recall.

Edited by Tony D
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I'd choose to leave what's in there...in there.

Well... being as the lines are rusted through and broken off in a couple spots, I really really should replace them  :icon10:

So i mean, sure 5/16 is fine, but 3/8 wont hurt right? Well.. techinically i guess it would take a hair longer to fill up and build the proper pressure but whos gonna notice! :P

3/8 feed and 5/16 return sound about right? is there any reason not to? 

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Incomplete information up front wastes everybody's time.

 

Put what you want in there, it's been beat to death it won't make a shite bit of difference in your application.

 

Unless, of course you're playing more games and withholding more information.

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  • 3 weeks later...

No, as I recall he used the Swagelok fittings for the tubes, and the Swagelok to AN adapters (SS) at the ends where the interfaces were with his existing AN Softlines. He also put a -8 fuel line and -6 return into the stock tank sender unit...

 

My suggestion to anybody doing this is to make the lines in three portions: underfloor (firewall to back shelf upswing), fuel pump/fuel tank section, and engine bay section.

 

For people developing a project, the engine bay configuration may change several times, as may your fuel pump configuration. This allows you to remake and reconfigure the applicable section without having to drop your fuel line and make a break there later, under the car, crap falling in your face & swearing!

 

Plus, it GREATLY simplifies the bending orientation. The complex stuff is at the ends and it's MUCH easier to handle as a 6' stick rather than one 12' long with orientation of every prior bend to worry about.

 

I mean, you can try to duplicate the stock one-piece line and if you can do it in one go...more power to ya! But if you get everything perfect, and make the very last bend so the feed nipple now goes out the inner fender well, instead of towards the engine....don't say you weren't forewarned! And you will end up cutting it at the firewall anyway...muahahaha

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Oh, you know what, he DID do AN Flares on that tubing! I remember the swearing....

 

It was seamless 0.035" wall stuff. If you can the get thinner stuff, it will flare easier, just use a LOT of MOLYKOTE on the inside of the swage area...and use a GOOD tool with the rollers on the cone, it will come out glass smooth on the inside then.

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