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Fuel Filler Neck and Cell Vents, learn me!


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Recently switch to a fuel cell in our E30 for a long list of reasons.  

 Wondering what teams are using for a fill neck?  We have the hunsaker 5gal cans with clear 2.25" od hoses.  Ideally would like a neck that could accommodate this hose while filling without any reducers.

What fill neck plate is everyone using? 

 

Also would like to be learned on the fuel cell vents.  Our fuel cell top plate has an internal ball check valve in the event of a rollover. Is this sufficient. Any other trick to venting a cell. Mounting location/routing/height? 

How does this discriminatory valve work that I've seen some people use, do I still need that with the ball valve? Advantages/disadvantages?

 

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Edited by Shane G.
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A discriminator valve won't allow fuel to pass, preventing your gas from spraying out the vent line on the first left hand turn you make after filling up. The rollover ball style check valve doesn't do anything for this.

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During inspection in 2020. Jay wanted the vent to go right out the back. Around the licences plate area. Passed me on what I thought was right said next time he see the car needs to be out the back. I will need a discriminator valve because of my vent will be about 14" long from the cell to out the back. Sure to spray with this short distance? Anybody got an example to share on valve and placements. 

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2 hours ago, TimS said:

My plan if and or when I switch to the fuel cell is to have a straight fill hose in trunk. A take on this setup. No dry breaks either. 
 

These are a pita to fill, especially if you have a wing. We got penalized 5 min last race because of spillage because it was hard to lean over the car and get the spout in and out.

You're holding the 5 gal jug with the spout strait up with one hand and with the other hand you have to bend the 2.25" hose till the spout is straight down. Not easy and leads to spills.

Edited by Dimsun Racing
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1 hour ago, TimS said:

My plan if and or when I switch to the fuel cell is to have a straight fill hose in trunk. A take on this setup. No dry breaks either. 
image.jpeg.f381e9ca0d0122161d01bb7fce4248ff.jpeg

  Only allowed 1 fill port, unless your car came with more stock. Hope this guy never backs this one into the wall or takes a hit to the rear body.

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11 minutes ago, Dimsun Racing said:

These are a pita to fill, especially if you have a wing. We got penalized 5 min last race because of spillage because it was hard to lean over the car and get the spout in and out.

 

Very true, that looks like a terrible idea, much easier to fill from the side of the car. Watch pit stops from LeMans or Daytona of purpose built endurance racers, you want the fill on the side and as high up as possible. Another important point for what we do is to put the filler on the passenger side, so you are not in the way of the driver changes. Back when it was being argued about being able to fuel hatchback cars with the driver in the car I always shook my head and wondered how anyone could consider it safe to fuel a stock Miata in a race situation, you have fueling going on 6 inches from the driver change, how is that a good idea?

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4 hours ago, Shane G. said:

Recently switch to a fuel cell in our E30 for a long list of reasons.  

 Wondering what teams are using for a fill neck?  We have the hunsaker 5gal cans with clear 2.25" od hoses.  Ideally would like a neck that could accommodate this hose while filling without any reducers.

What fill neck plate is everyone using? 

 

Also would like to be learned on the fuel cell vents.  Our fuel cell top plate has an internal ball check valve in the event of a rollover. Is this sufficient. Any other trick to venting a cell. Mounting location/routing/height? 

How does this discriminatory valve work that I've seen some people use, do I still need that with the ball valve? Advantages/disadvantages?

 

 

I do a lot of crewing in one of the other series, the biggest problem I see with racecars is not having the largest Hunsaker spout available. Sure you have 5 minutes but if you use up all that time fueling it leaves less time for other necessary things during the pitstop. Like say if you have to sort a radio issue. It's getting so competitive you can't make mistakes anymore and stay in the running.

 

The biggest Hunsaker spout is a 2.25" ID hose (not OD).  This will dump 5+ gal of  fuel in 5 seconds, everything else is in the dust. This means you need a 3" OD filler neck and the preferred location is on the passenger fender, not the trunk lid.

https://hunsakerusa.com/collections/5-gallon-quikfill-jugs/products/5-gallon-quikfill-fuel-jug-w-2-25-x-2-25-quick-dump-hose-kit

 

3" OD filler neck

https://www.fillernecksupply.com/3-inch-weld-in-on-filler-neck-nf1969-lebow-eaton-caps-necks-nf1969/

 

3" OD fuel cap
 
to connect the filler neck to the tank you may be able to get a piece from Hunsaker, or if not then Pegasus, Some series want to see the reinforced hose. Clear hose is preferred so you can see the fuel level when it's near full.
2.25" ID fuel hose
 
I just welded in a piece of 2.25" OD steel muffler tubing into the top of the fuel cell plate to connect the cell to neck. I did bead the lip.
 
Here's another similar neck/cap. Some of these race shops are not into the spirit of "budget" racing.
 
With this fast of a fill you need a large breather, I used a -16 steel braid hose and looped it on itself then put the outlet under the gas cap so the drip pan catches both. I've seen this done in SCCA ect. Probably not as good as a discriminator valve though. Not sure what happens if the car is turned over but never had a leak otherwise.
Edited by Dimsun Racing
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Sorry for not showing an exact mock up photo. Filler point would be at the to of the trunk, so no leaning over. Single fill hose of course, no dry break. IMO Filling from the side exposes spilled fuel to hot brake rotors and adds several turns to the fill pipe. It also has the fill pipe at a shallow angle. I don’t have a giant wing on my car either. I wanted to keep fuel pumps, surge tank, fill and associated pieces close to together to make bulkhead simpler to construct. Just my thoughts and ideas. No plans for the fuel cell right now so just ideas bouncing around 

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We are installing our new cell as we speak. 

 

Same fill plate. We will run a 1.5” discriminator on the vent sold by ATL and run that to near the fuel fill location. We then run a 3/4” overflow line straight out the back to a dry break connection that we run a catch can to. When cell is full the fuel flows out of the overflow telling us the cell is full. The discriminator will shut off the vent preventing any fuel from exiting out the vent line. 

 

Filler has a flapper valve for rollover

Vent has a rollover valve and the discriminator acts as one as well.

Overflow also has a rollover valve

 

When finished fueling we detach the overflow and its a sealed system so no fuel spills out on track. We ran a similar setup last year on our cell but with a 3/4” vent and discriminator and we never leaked fuel.

 

We fuel from the oem location 2.25” hunsaker necked down to 1.5” to fit into our fuel fill location. Necked down to 1.5” they still dump in like 12 seconds. Looking at your filler neck the slope of the filler hose might not be steep enough to dump one at full send. I know we couldn’t with our last setup.

Edited by Gkuhn41
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10 hours ago, Gkuhn41 said:

We are installing our new cell as we speak. 

 

Same fill plate. We will run a 1.5” discriminator on the vent sold by ATL and run that to near the fuel fill location. We then run a 3/4” overflow line straight out the back to a dry break connection that we run a catch can to. When cell is full the fuel flows out of the overflow telling us the cell is full. The discriminator will shut off the vent preventing any fuel from exiting out the vent line. 

 

Filler has a flapper valve for rollover

Vent has a rollover valve and the discriminator acts as one as well.

Overflow also has a rollover valve

 

When finished fueling we detach the overflow and its a sealed system so no fuel spills out on track. We ran a similar setup last year on our cell but with a 3/4” vent and discriminator and we never leaked fuel.

 

We fuel from the oem location 2.25” hunsaker necked down to 1.5” to fit into our fuel fill location. Necked down to 1.5” they still dump in like 12 seconds. Looking at your filler neck the slope of the filler hose might not be steep enough to dump one at full send. I know we couldn’t with our last setup.

Any chance you could share some pictures?

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3” filler hose is allowed. Maximize that diameter and position your fill port as far from the cell as possible... if you can find a way to put the fill in the front for a rear cell, do it, that’s worth 3 gallons right there. Also as others have said, picture the process of pouring a full jug of fuel... you need to EASILY and QUICKLY get the hose in without spilling a drop and then tip the fuel jug upright. Any design (like the in-trunk fillers) is a recipe for spilled gas. 
Also, Jay had a lot of ideas about fuel vents and overflows and whatnot and those aren’t in the rules and Jay isn’t around anymore... he often confused the vapor vent and overflow. You don’t need an overflow, just a vapor vent, and if your vapor vent runs high enough and close enough to vertical, you don’t need a discriminator valve. 
With my install, the fill neck goes a little above and behind the stock fuel door on the side of the trunk, the vapor vent goes to 1” below the roof. 

Edited by enginerd
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40 minutes ago, enginerd said:

if your vapor vent runs high enough and close enough to vertical, you don’t need a discriminator valve.

 

40 minutes ago, enginerd said:

the vapor vent goes to 1” below the roof. 

 

What do you have installed in the vent to prevent flowing in the event of a rollover?

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49 minutes ago, enginerd said:

3” filler hose is allowed. Maximize that diameter and position your fill port as far from the cell as possible... if you can find a way to put the fill in the front for a rear cell, do it, that’s worth 3 gallons right there. Also as others have said, picture the process of pouring a full jug of fuel... you need to EASILY and QUICKLY get the hose in without spilling a drop and then tip the fuel jug upright. Any design (like the in-trunk fillers) is a recipe for spilled gas. 
Also, Jay had a lot of ideas about fuel vents and overflows and whatnot and those aren’t in the rules and Jay isn’t around anymore... he often confused the vapor vent and overflow. You don’t need an overflow, just a vapor vent, and if your vapor vent runs high enough and close enough to vertical, you don’t need a discriminator valve. 

I like all of this. 

100% agree that the in-trunk fillers are not a good idea. We were told to do this with our Cobra by the same person who had "a lot of ideas". Even though the BCCR doesn't require it. The idea of of having fuel slosh around in the trunk when it inevitably spills when filling or slightly overflows when full sure seems like a bad idea. 

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56 minutes ago, Burningham said:

What do you have installed in the vent to prevent flowing in the event of a rollover?

Our cell has the rollover steel ball check valve thing installed on the fill plate, like Bandit said.

 

Now, I can see a bad situation where the car goes almost onto its side, check ball stays down and fuel can flow out. This would be an issue if the cell is at least 1/2 full and car is mostly on its side but slightly more upright than turned over. We would definitely dump gas in that situation. 

Edited by enginerd
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4 minutes ago, enginerd said:

Our cell has the rollover steel ball check valve thing installed on the fill plate, like Bandit said.

 

Now, I can see a bad situation where the car goes almost onto its side, check ball stays down and fuel can flow out. This would be an issue if the cell is at least 1/2 full and car is mostly on its side but slightly more upright than turned over. We would definitely dump gas in that situation. 

 

Yeah I have wondered about that situation.  Because of that I run my vent like this:

 

image.png.59732046c88c0c9c71d6ace83a996114.png

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1 hour ago, enginerd said:

3” filler hose is allowed. Maximize that diameter and position your fill port as far from the cell as possible... if you can find a way to put the fill in the front for a rear cell, do it, that’s worth 3 gallons right there. Also as others have said, picture the process of pouring a full jug of fuel... you need to EASILY and QUICKLY get the hose in without spilling a drop and then tip the fuel jug upright. Any design (like the in-trunk fillers) is a recipe for spilled gas. 
Also, Jay had a lot of ideas about fuel vents and overflows and whatnot and those aren’t in the rules and Jay isn’t around anymore... he often confused the vapor vent and overflow. You don’t need an overflow, just a vapor vent, and if your vapor vent runs high enough and close enough to vertical, you don’t need a discriminator valve. 
With my install, the fill neck goes a little above and behind the stock fuel door on the side of the trunk, the vapor vent goes to 1” below the roof. 


3" Steel OD = 2.875" ID = 6.49 cuin per inch :  35.6" = 1 Gallon
2.5" ID Tube = 4.91 cuin per inch : 47" = 1 Gallon

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1 hour ago, enginerd said:

if you can find a way to put the fill in the front for a rear cell, do it, that’s worth 3 gallons right there.

 

I've seen a couple of teams get told they need to do a direct route from filler to tank.  When I asked both old and new tech regimes about what I could or could not do for filler relocation I was told that if it is not a direct route it will earn some re-work before you go on track.  I assumed it would make it into the tech-desk, but I can't find it under any searches now. 

 

This is the sort of lack of policing and definition that drives me nuts. 

 

 

 

A 3 gallon fuel filler line would be a real John Holmes set up.  2-1/2"ID hose (3" OD) is roughly 1/3 gallon per foot.

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9.10.3.2. 3” MAXIMUM O.D. for all fuel fill lines.

9.10.3.3. MAXIMUM -8 (AN) or 1/2” I.D. shall be used for all fuel lines from cell/tank to the engine.

9.10.3.4. All fuel lines must be routed in the most direct (shortest distance) path to and from source/termination point. 

 

 

9.10.3.4 doesn't say "fuel fill lines" but I'm guessing that is how tech is interpreting it.

 

While extra gas is always good, don't know if I'd be a fan of a John Holmes fuel filler tube snaking it's way through the car. No matter how shielded it is.

Edited by Bandit
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Full disclosure: I want people to build absurd fuel fillers so that the series is forced to make a rule restricting them. I have seen some over the years that I would say “fix by next event or you’ll be in EC” if I were tech. I supported @Chris Huggins petition about maximum filler capacity but it wasn’t approved. 

 

The hose has to be direct from A to B, doesn’t specify where A and B have to be.... just that they have to be properly walled off from the driving compartment. 
 

@Burningham that would do the trick! I’ll add a section of hose for that extra jog left, should be easy and effective, thanks!

Edited by enginerd
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52 minutes ago, enginerd said:

Full disclosure: I want people to build absurd fuel fillers so that the series is forced to make a rule restricting them. I have seen some over the years that I would say “fix by next event or you’ll be in EC” if I were tech. I supported @Chris Huggins petition about maximum filler capacity but it wasn’t approved. 

Max capacity might be a bit too ticky tacky and "complicated".

 

Just say either stock filler location OR filler location behind rear wheel opening (or possibly rear axle centerline) directly to the cell.

 

Any cars that can't meet that?

Edited by Bandit
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32 minutes ago, Bandit said:

Max capacity might be a bit too ticky tacky and "complicated".

 

Just say either stock filler location OR filler location behind rear wheel opening (or possibly rear axle centerline) directly to the cell.

 

Any cars that can't meet that?

I prefer a rule that says “don’t abuse the lack of rigid rules on filler location and length for fuel capacity gain. If you do, you get bumped to EC at the discretion of tech. We will know it when we see it.”

 

I know vague discretion rules like this are reviled by racers but I think they are needed at times to smack a Smokey Yunick off the podium without having to wait for the new rulebook to come out. In this case, I would welcome a bit of “don’t screw with us and we won’t screw with you” but tech needs the authority/chutzpah to make it work. 

Edited by enginerd
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4 hours ago, Burningham said:

 

Yeah I have wondered about that situation.  Because of that I run my vent like this:

 

image.png.59732046c88c0c9c71d6ace83a996114.png

 

1 hour ago, enginerd said:

 

@Burningham that would do the trick! I’ll add a section of hose for that extra jog left, should be easy and effective, thanks!


@enginerd and @Burningham I like the routing shown for the vent tube. how do you guys properly shield that from the interior, is it all within inner panels in your car(s), or do you use metal lines for the vent tubes?

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