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joesurf79

Is this fuel line routing going to be NASA legal ?

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I had routed the hoses outside the car for a majority of their length, but for a variety of reasons (accessibility for inspection, easier control of motion / abrasion potential, fewer contact points, no possible exposure to moving suspension parts / axels, lower risk of impact damage causing a leak, etc. ), I think routing through the car (See diagram) is safer on the whole in this instance. But is it NASA legal for the stainless braided fuel lines to pass through a grommet in the 1st bulkhead, then through the cabin to the next bulkhead (factory fuel tank cover) where they'll pass through a grommet and be connected on the other side of the 2nd bulkhead? So no exposed connections open to the cockpit - just the stainless lines. Or will I have to build a "box" of sorts over the lines the whole way?

 

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The way I read the rules I think it should be legal, right? What I found :

11.4.17 Hoses Inside Cockpit

All hoses carrying any hot or flammable liquids should be metal or reinforced

15.4 Fuel Cell / Tank:

11. A single external (to the fuel tank or fuel cell) container that fuel is stored in, or moves through, (e.g. swirl pots, vent cans, surge tanks, etc.) may be used, and that container shall not have a capacity greater then 1.5 liter (0.4 gallons). The container must be constructed of aluminum or stainless steel, with threaded fittings to stainless steel braided fuel hoses. It must be separated from the driver's compartment by a separate bulkhead. Any container over 1.5 liters (0.4 gallons) is considered to be another fuel cell and subject to fuel cell requirements.

15.14 Hoses Inside Cockpit

All hoses carrying any flammable liquids or any toxic or flammable gases that go through the cockpit must be metal or steel braided or reinforced.

 

Seems to me that the surge tank has to be bulkheaded off, the factory tank already is, and the line between them will be braided stainless. Any scrutineer types want to chime in? :) @blk96gt  @V6Donut - you guys have any insight or experience with this?

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Not that I can offer anything of value, but wanted to give you a nod on the paint skills. I’m a bit of a paint connoisseur myself.

Only thing I can think of - any mention of “grommet spec” at the bulkhead?  i.e. to ensure proper grommet size is used for your particular braided hose size.  I have zero experience so just spitballing...

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25 minutes ago, Solo_S14 said:

Not that I can offer anything of value, but wanted to give you a nod on the paint skills. I’m a bit of a paint connoisseur myself.

Only thing I can think of - any mention of “grommet spec” at the bulkhead?  i.e. to ensure proper grommet size is used for your particular braided hose size.  I have zero experience so just spitballing...

No mention of grommet spec. 

That paint picture diagram was the most productive thing accomplished during the call I was on...

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Or I guess how they define the bulkhead / required “sealing” of the bulkhead.  Safer to ask two dumb questions than to overlook something 👍

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For

8 hours ago, Solo_S14 said:

Or I guess how they define the bulkhead / required “sealing” of the bulkhead.  Safer to ask two dumb questions than to overlook something 👍

I was told by the NASA tech inspector at COTA in May that many people use 3M fire resistant sealant (think it was called "Fire Shield caulk") to seal the edges of the bulkhead. But I forgot to chat him up again and get all of my questions answered before I left. Thus my paint diagram driven plea for knowledge lol :pardon:

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Digging around the 'ole interwebz, it seems that the world falls into two camps (naturally). Those that agree with my reasoning on the safety benefits above, and those that think my IQ is in the low single digits for considering running fuel lines in the car. But - it seems my plan is considered legal. Making lines tonight!

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best advise I can give is to contact a certified NASA annual tech inspection location and ask them.  or Hank himself

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15 minutes ago, V6Donut said:

best advise I can give is to contact a certified NASA annual tech inspection location and ask them.  or Hank himself

Thanks Chase, I emailed the NASA TX information box on the site, asking for Hank's contact email. Obviously final "legality" depends on the actual execution of the work, but a conceptual check would be rad. 

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Agreed with the philosophy.  As far as I know, metal braided lines are considered acceptable as long as there are no fittings in the cabin to make it possible to leak.  you've covered that.  but the issue is making sure local NASA tech is OK with it AND that it's done correctly.  all the verbal in the world is OK if you wind up with crap workmanship and the inspector deems the job unsafe at any speed.  (My dad had that problem in OK because he built his own cage.  It was Ok for WRL, SCCA, COMMA, and a couple other groups he ran with... but then the NASA guy saw one thing he didn't like and wouldn't let him on track, even though he'd been racing with multiple other series for years...)

Regarding the fire-stop, the 3m firestop caulk is one way to do it, but it's literally slathering caulk around a hole through sheet metal fitting.. it won't be pretty and may not last terribly long before vibrations and stress on the lines causes the stuff to come loose and you have a small air gap.

i would recommend routing the hoses in such a manner that they are fixed on at least one side of the bulkhead.  i.e. run it against rear strut tower and attach the hose to it just before going through the firewall.  you then use grommet at the firewall and block with firestop on the back side where you don't care about an ugly glob of goo packed around the hose.

 

 

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You can also get fire-retardant "great stuff" expanding foam. We use it to fill gaps between cables going through fire barriers. They sell it at Home Depot, and it's red.

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