Nhra fuel line routing
 

How are you guys routing your fuel lines to pass tech?


And I know some hillbilly tracks don't check, but assuming they do.

Re: Nhra fuel line routing
 

Do you mean where they are routed?

From the NHRA rulebook:
Lines: All non-OEM fuel lines (including gauge and/or data
recorder lines) must be metallic, steel braided, or NHRA-accepted
“woven or woven-pushlock.” A maximum of 12 inches total (front to
rear) of non-metallic or non-steel braided hose is permitted for
connection purposes only; individual injector nozzle and motorcycle
fuel lines are excluded. Fuel lines (except steel braided lines) in the
flywheel/bellhousing area must be enclosed in a 16-inch length of
steel tubing, 1/8-inch-minimum wall thickness, securely mounted as
a protection against fuel-line rupture. Fuel lines may not be routed
in the driveshaft tunnel. It is mandatory that fuel lines passing
supercharger drive belts be steel braided, NHRA-accepted woven
or woven-pushlock, or be enclosed in protective steel tubing. A
current list of NHRA-accepted woven or woven-pushlock fuel lines
is available on NHRA.com. All NHRA-accepted fuel lines must use
ends that are specifically designed for the type of fuel line being
used. No hose clamps allowed on NHRA-accepted fuel lines.
Pumps/Valves: Cars with non-OEM-type mechanical fuel pumps
must have a quick-action fuel-shutoff valve within easy reach of
driver and located in the main fuel line between the fuel tank and
the carburetor and/or injectors. Fuel recirculation systems not part
of normal fuel/pump system prohibited. All cars in Stock, Super
Stock, Competition, and Pro Stock must be equipped with a
positive-lock drain valve located between the fuel tank and the
carburetor(s) or fuel injector to facilitate removal of fuel samples for
fuel-check purposes.

Re: Nhra fuel line routing
 

I read that, but how are you guys running them? I don't see how it's possible to not route it in the transmission tunnel, and some folks are suggesting the transmission tunnel is considered the driveshaft tunnel.

-- Joe

Re: Nhra fuel line routing
 

I just finished my lines
I have my fuel pump in the passenger rear, and ran the line inside the rear passenger wheel, along the subframe connector, and then to the front wheel inner fender and then to the front
https://imgur.com/a/E6FYDci
https://imgur.com/a/E6FYDci
https://imgur.com/a/E6FYDci

Re: Nhra fuel line routing
 

Hrmm. No concerns there and it passes tech?

-- Joe

Re: Nhra fuel line routing
 

Don't know yet, it's still not running

Re: Nhra fuel line routing
 

Steve? Anyone else ?

Some of you guys have 9 second cars that have to pas stringent tech. How have you routed your fuel lines?

I have braided PTFE from the fuel rail back. I was running it in the trans tunnel but Justin pointed out that it might be argued that the trans tunnel is the "driveshaft tunnel"...

I don't wanna do this 3 times.

-- Joe

Re: Nhra fuel line routing
 

LOL! My fuel line is about 2 feet long. It goes from the bottom of the cell mounted beside a small rad and goes to the belt driven pump. The pump outlet goes to the barrel valve on the intake. Any fuel not used gets returned to the inlet side of the pump.

Way back when I had the fuel cell mounted in the back, I simply ran the line under the car then had it come out on the driver's side of the transmission tunnel.

I think the main thing tech will be looking for is that when it passes the flywheel area, it needs to be protected. Steel braided hose is considered protection but tech may still question it. A hard line going past the bellhousing area will always pass tech. The fuel line could also be shielded by a metal plate. The whole idea is if you explode a flexplate or flywheel, you don't want shrapnel to take out a fuel line.

In reality, your fuel line should be similar to how OEM fuel line is run. As much hard line as possible with minimum rubber hose. Steel braid hose is acceptable but plain rubber fuel line can not be longer than 12" total in the whole fuel system. When I worked tech during street legal nights, I would fail a Chev if it had a mechanical fuel pump and a simple rubber hose running from the pump to the carb. That won't pass tech. It's just not safe.

I bought a 37* flaring tool for the few hard lines I run on the engine. Making the lines so they can be attached to JIC fittings is so clean and leak proof.

Re: Nhra fuel line routing
 

Steve, this seems to indcate steel lines bassing the bell housing would not pass tech:

Re: Nhra fuel line routing
 

I guess they figure steel lines are not as puncture resistant as a steel braided line.

As for driveshaft tunnel, they don't want fuel lines beside the driveshaft in case a u-joint fails and the driveshaft takes out a fuel line.

It's hard on our cars but I know a few racers who have run the fuel lines inside the frame rail.

Re: Nhra fuel line routing
 

I looked at it more this evening on the lift and I'm struggling with how to run it outside the tunnel.. Unless I drill holes and run it through the frame.. I feel like hanging out by the suspension / wheel is just as bad.

I have a few rolls of steel line and a 37* flaring tool and a box of fittings (tube nuts, etc). I can go hard line most of the way and run braided just in the engine compartment.. If I can figure out the best way to run these lines.

-- Joe

Re: Nhra fuel line routing
 

As per the rules, running braided lines past the bellhousing is fine. If I remember correctly, mine ran right up on the drivers side and came into the engine compartment on top of the frame rail.

Technically, you can run braided lines from the tank right to the carb if you want since steel braided lines are the easiest way to run lines. Just keep them out of the driveshaft tunnel.

Transmission tunnel is not the driveshaft tunnel. You just don't want the lines in the immediate area of the driveshaft.

Re: Nhra fuel line routing
 

Can steel lines cross over the transmission, or is that considered the driveshaft tunnel?

Like if I cross through the frame from left to right midpoint?

Re: Nhra fuel line routing
 

Transmission is transmission. Driveshaft tunnel covers the driveshaft.
I wouldn't want lines going over the transmission either. I've seen them explode and trans shields can only protect so much.

Re: Nhra fuel line routing
 

Not many check this rule. Its stupid cuz then every stock car is illegal as lines run down driveshaft tunnel.

I might do mine down subframe connector

Re: Nhra fuel line routing
 

Justin, oem lines are exempt. The whole thing is dumb . I can buy a 2008 stock italian car and go 11s without a cage, but put a blower on an 85 mustang and all of a sudden I need a list of stuff.

Anyhow, I think maybe cross over to the passenger side and run them along the subframe connector is my best bet.

Re: Nhra fuel line routing
 

Can you run oem lines then and after trans area, adapt to braided line? Lol

Re: Nhra fuel line routing
 

That's what most people do, but like a retard I removed the stock lines a few years ago.

I'm running 3/8" fuel and return. I'm concerned that a 5/16 return might not be large enough for the 410lph pump, but it could be all in my head.

Either way, I think if I bent up some new 3/8" lines and routed them the same way stock was, the track would call it non-OEM.

-- Joe

Re: Nhra fuel line routing
 

I doubt it. What are the chances they are experts in thirdgens and what is stock oem and what is not?

My buddies 7 sec trans am is never questioned at any track, not just my hillbilly track. Braided lines down stock location lol. He meets all other safety regs

Re: Nhra fuel line routing
 

Good point..

Stock location though passes the flywheel area.

I dunno. I'll look at it more tonight.

-- Joe

Re: Nhra fuel line routing
 

Spoke to the track manager, he said it can run in the transmission tunnel as long as its along the frame.

Cannot be on the transmission or bell housing.

But steel can't pass the flywheel area unless it's in a metal tube.

I actually wonder if welding a metal tube isn't a bad idea, as it would shield from the headers too..

-- Joe

Re: Nhra fuel line routing
 

But what about driveshaft tunnel?

Re: Nhra fuel line routing
 

So, you can't have any lines hanging out in the driveshaft tunnel at all, but they can be against the inside of the frame if the frame is part of the tunnel.

In the example of a thirdgen, the frame hangs down a little in the driveshaft tunnel, and that is OK because it's against the frame. But the factory routing has two problems:

1) Part of the line will be in the driveshaft tunnel, where there is no frame, so fail

2) Even against the frame, the line will pass the flywheel area, which is a fail unless it's metalic braided or encased in 16" aluminum tube, 1/8" wall thickness.

So OEM style routing is a no-go, unless it's the original factory lines.


OEM routing is designed to prevent a fuel leak in a side impact. NHRA routing is designed to prevent a fuel leak in a drive line failure. Yet another example of race car rules being unsafe on the street.


-- Joe

Re: Nhra fuel line routing
 

You starting to see where i come from now? Lol

Re: Nhra fuel line routing
 

Starting to wonder if I should just remove the license plates and leave the car in my enclosed trailer.

If I put the cage in it, I won't want to drive it in the street anyway.

-- Joe

Re: Nhra fuel line routing
 

why are they so accepting of braided line anywhere but steel tubing is a major risk factor to them? what advantage does braided line have over regular fuel line tubing?

I can see an AN fitting and braided line failing wayyyyy before I could see a non rusted steel line failing. even if the bellhousing was to grenade itself I think the steel line would have a better chance at surviving

Re: Nhra fuel line routing
 

I tried this myself.

Take a hatchet, and whack a steel line. It leaks in 2 seconds.

Now do the same to braided. You can whack it 100 times and it doesn't leak.

-- Joe

Re: Nhra fuel line routing
 

I just ran my lines along the factory pathway. I run a -8An feed line and -6an return line. PTFE stainless steel braided and coated in black plastic shrouding. as per everyones discussion here, it appears my setup will indeed pass tech (phew).

Re: Nhra fuel line routing
 

Not unless it turns out of the tunnel before the tailshaft.

The factory routing is a big no-no, even with braided ptfe like I have.

-- Joe

Re: Nhra fuel line routing
 

Re: Nhra fuel line routing
 

Everyone has different opinions. Some folks say AN hose causes flow reductions. PTFE is supposed to be more like rigid line.

-- Joe

Re: Nhra fuel line routing
 

Nothing wrong with braided line. It works. After few yrs you may have fuel smell leach out.

The braided nylon or braided ptfe lined hoses will not have that and last longer. Ptfe costs more and uses different fittings.

Stock size line supports alot of power. Usually going dual 255 or bigger would require -8 an imo which is 1000 whp worth of fuel on gas

Re: Nhra fuel line routing
 

I did the calc on that yesterday actually. At 20 feet of line, and 105 gallons per hour flow rate, pressure drop on -6 was 2.4psi, on -8 it was 2.2 psi, this was at 70psi outlet pressure.

Interesting to note, on a carb application where the outlet pressure is lower sees a significant pressure drop (in percentage) vs EFI pressures. This is probably why the carb guys run such huge lines for relatively low HP applications. A 3% pressure reduction on EFI vs 30-40% on a carb application.

-- Joe

Re: Nhra fuel line routing
 

Thank you, I said this for years !

I used -10 to feed a 680 HP carb setup. -8 would have worked but I sized the lines to run E85. I switched back to gas so I have have room to grow and not redo fuel system.

I followed the OEM routing but on the passenger side & never had an issue with it.