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NHRA restrictions on fuel line?


SleeperZ

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I am plumbing a new fuel system in my engine compartment. I'm still using the stock lines from the tank. It seems the NHRA regulations on rubber fuel line is 12" total length in the entire fuel system is all you're allowed.

 

That immediately seems to disqualify any fuel injected Z (unless OEM is allowed, which I assume is the case). But I'm putting in a new fuel rail and adjustable regulator. And I am also "cheap" - I wanted to run plain old fuel injection hose from the feed into the filter, across the engine to the rail, around the back of the engine to the regulator, and out of the regulator to the return line.

 

Obviously this is not OEM, violates NHRA regulations, and may not be safe. Can I have some recommendations on plumbing this? Remember I'm cheap and AN fittings seem outrageously priced. I was planning to run 3/8" line through the filter and to the rail, and 3/8 to the regulator as well, all brass barbed hose fittings and 3/8 NPT pipe threads.

 

Will I have to use AN stuff? Should I run aluminum hard line around the engine, and what fittings can be used with that? Does steel braided rubber line count as "rubber line"? I will obviously be drag racing this, and don't need any tech hassles...

 

Also - firewall mounting of the regulator is not allowed as well? Where else would you mount the thing so you don't have to run miles of pipe/hose?

 

What have you folks done? bonk.gifburnout.gif

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Guest greimann

I don't know about NHRA regulations, but I am a big fan of steel line and AN fittings. The picture in the link below shows -6 steel tube that is bent and flared for 37 degree JIC (also known as AN) fittings, combined with steel, not aluminum, tube nuts. Bending steel line is a piece of cake with a bender and flairing is also easy, with the right tool. Note that 37 degree tubing does not require double flaring like 45 degree fittings do, so that aspect is much easier. These fittings are typically found in industrial catalogs like MSC and Grainger, and are suited for hydraulic systems. Aluminun lines and fittings were originally developed for aircraft where weight is a primary concern. I would feel uneasy running aluminum line on my vehicle where durability and safety are paramount. I can give you some part numbers if so interested

 

http://home.earthlink.net/~dvgreimann/largeimages/fuelinjection.jpg

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I appreciate the input G. Does anyone know how the NHRA regulations are interpreted, or to what extent they are enforced? I intend to be running 12s this upcoming spring, and I don't want to run a fuel system that will keep my car from running.

 

Does anyone know whether steel-braided fuel line counts as rubber line? Twelve inches is not a lot of leeway given I have pump connections, a supply and return, AND injector hoses. I estimate the stock Z has over 4 feet of rubber hose in the fuel system!!!!!

 

Please help.

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well tech will nail your ass for too much rubber line. dammit nathan why did'nt you ask me? i just tossed a 4ft junk of hard line in the trash. you will have to go with braided steel line along the firewall. they will NOT allow even hard aluminum line along the firewall. (they say that if the clutch explodes it would take out the aluminum line but not the braided line.) what are you looking to do nathan? i have some extra braided line and a bunch of fittings, maybe we could come up with something.

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Here are my tentative plans at the moment. I just bought a big fuel filter with 3/8" NPT, and I'm planning on buying the Aeromotive regulator, again with 3/8" NPT fittings. I found some braided stainless line at Summit with a 3/8" ID, so I was going to run 3/8" ID line from my filter with 3/8" hose barbs and fuel injection clamps to 3/8" fittings on my fuel rail, and the same thing to my regulator. The regulator and the filter will both have short runs of 5/16" hose (regular rubber, short lengths) to the stock lines.

 

I went with the 3/8" hose because I want to minimize the pressure drop to my regulator, and to increase volume in the rail.

 

Which begs a question here - where can I mount the regulator? Why is the firewall not a good place?

 

BTW - I've priced that AN fitting stuff, and I cannot foot $15 a fitting for -6 or -8 stuff; that is just WRONG! I've always had good luck with brass hose barbs, so I'd like to stay with it.

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Well, found the NHRA sport compact rulebook online today, and got some more answers.

 

The reason the FPR should not be mounted on the firewall is it's right inline with a clutch explosion. The FPR and any other fuel system components need to be at least 6" forward of the clutch assembly.

 

Also, they prefer steel-braided lines over just about anything, as supposedly they will survive a clutch explosion better than most anything, save shielded hard lines. The 12" rubber limit does not apply to braided steel fuel hose or individual injector connections, so this shall have to be my limit when connecting the stock hard lines to my fuel filter inlet and the FPR return.

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Use AN fittings. Don't want to pay the price? Use the steel ones sold at NAPA and hydraulic shops forover the road trucks etc. It's WAY cheaper, heavier, won't strip as easily, and generally has to be crimped on. Best to measure out everything and have them crimp the fittings on for you. It will be SECURE and well worth it. It's what's on my Supra and works well....

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