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 Post subject: Fuel Cell Venting
PostPosted: Mon May 07, 2018 7:49 am 
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Joined: Fri May 06, 2016 11:06 am
Posts: 16
Location: SE NM
I need to redo my fuel cell venting and I was curious what design/routing for the vent works best. Reading around, it's a bit polarized about if a 360deg loop should be integrated or not. The ATL and Fuel Safe directions are pretty non-specific. Following the other cars on-track, some have a bunch of fuel dump out the vent on the first few laps and others don't. Having a rotary which already has plenty of flames out back I would prefer to keep as much fuel in the cell as possible. I need to keep any pressure drops over the length of the vent low to keep the inlet suction at my pump to a minimum. Any tips or go-to designs?

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A. Sanford
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 Post subject: Re: Fuel Cell Venting
PostPosted: Mon May 07, 2018 8:28 am 
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Joined: Fri Oct 30, 2009 5:47 am
Posts: 323
I have always done at least one complete loop in the hose and vent out back usually behind bumper, I have never been told of any leaking issues this way.

Les

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Les Chaney
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 Post subject: Re: Fuel Cell Venting
PostPosted: Mon May 07, 2018 8:59 am 
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Joined: Fri Nov 06, 2009 5:08 am
Posts: 1176
Location: Philly
I think that having it extend up as high as possible in the area that the cell is mounted is important. This minimizes the amount that sloshes out.

I'm also told you want it to extend down below the bottom of the cell, so that in a roll over, it wont drain the cell. That seems harder in most installs, since the cell is often the lowest part of the car where it's installed. Proper vents should have a flapper to minimize leakage in a roll over.

One thing I've seen that is clearly a no-no is a hose that slopes downhill from the vent to the cell. Water will then find it way into the cell.

-Kyle


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 Post subject: Re: Fuel Cell Venting
PostPosted: Mon May 07, 2018 11:39 am 
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Joined: Mon Oct 26, 2009 5:55 am
Posts: 335
Location: Orrtanna, Pa.
On my FC I have a 360 loop and the outlet is above the left tail ight.

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 Post subject: Re: Fuel Cell Venting
PostPosted: Mon May 07, 2018 7:04 pm 
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Joined: Sat Aug 17, 2002 7:32 am
Posts: 2628
Location: DeWitt, MI
+1 for a loop......and I vent mine through a bulkhead fitting behind the cell. I loop it as high as I can and I zip tie the loop to the underside of the trunk cavity of my Sprite. My ATL has two output fittings and a vent fitting. All are AN6’s. So I put an AN6 bulkhead fitting into the trunk floor behind the cell and the looped line connects to that fitting. Easy, cheesy.

Dayle

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 Post subject: Re: Fuel Cell Venting
PostPosted: Tue May 08, 2018 12:18 pm 
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Joined: Mon Oct 14, 2002 6:08 pm
Posts: 592
Location: Raleigh, NC
Dayle:

Any pics?

Rick

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 Post subject: Re: Fuel Cell Venting
PostPosted: Tue May 08, 2018 12:31 pm 
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Joined: Sat Aug 17, 2002 7:32 am
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Location: DeWitt, MI
Rick Starkweather wrote:
Dayle:

Any pics?

Rick


I couldn't find any.....but this is easily solved.....I'll go take a pic of the trunk area when I'm down to the shop tomorrow.

Dayle

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 Post subject: Re: Fuel Cell Venting
PostPosted: Wed May 09, 2018 10:07 pm 
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Joined: Thu Dec 10, 2015 12:55 am
Posts: 121
I put a cell in my 2nd Gen RX7 last fall in place of the stock tank. I vented fairly strait up and out to a bulkhead fitting about 12" higher than the top of the cell. And it lost a lot of fuel. About 3 gallons in one 45 min race.

We spoke to some guys at OPM and they said they normally have to add loops. So we added 2 360 loops and now its fine.

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 Post subject: Re: Fuel Cell Venting
PostPosted: Thu May 10, 2018 3:13 am 
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Joined: Sat Aug 17, 2002 7:32 am
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Location: DeWitt, MI
Dayle Frame wrote:
Rick Starkweather wrote:
Dayle:

Any pics?

Rick


I couldn't find any.....but this is easily solved.....I'll go take a pic of the trunk area when I'm down to the shop tomorrow.

Dayle


Here’s shot looking down into the trunk cavity. I use zip ties to hold the loop as high as it can go in the trunk.

Dayle


Attachments:
IMG_May102018at71046AM.jpg
IMG_May102018at71046AM.jpg [ 143.03 KiB | Viewed 1411 times ]

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 Post subject: Re: Fuel Cell Venting
PostPosted: Thu May 10, 2018 4:24 am 
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Joined: Sun Aug 18, 2002 6:52 pm
Posts: 2142
Location: Topeka, Kansas
Here's what I use. https://www.pegasusautoracing.com/produ ... ecID=25780

Spring loaded check valve. Zero fuel gets out and only air can enter the cell. Works perfectly, call and talk to Bob Clark at Pegasus about it. The stock valves in fuel cells only have those roll over balls and do nothing for fuel slosh. I have this in my RX7 with no loop and no high hoses. Leaks zero.

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