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Fuel Filler Neck and Cell Vents, learn me!


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1 hour 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?

 

Lots of cars couldn’t meet that rule. Lots of front wheel drive cars have the fuel cell mounted in front of the rear wheels, and there is the rule allowing the fuel cell in the passenger seat area on 2 seat cars. In either case the best place for the filler is the B pillar, which is a good location since you can get it nice and high. I believe Mender has the filler on the front cowl for his Fiero.

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40 minutes ago, mcoppola said:


@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?

Up from trunk-mounted cell, through “B-shaped” hole in the trunk lid where it meets the rear window. Vent tube runs up the window (outside the car) to just below the roofline and then back down through the “B” into the trunk and the tube exits through a hole behind the right-rear wheel.

 

This is a Dave Johnson design... my vent tube was too low and/or not close enough to vertical (I kept it completely within the trunk) and we got to Road America, spilling loads of fuel in left hand corners. He figured “why not run it up the window outside the car?” We tried that and it worked great.

 

So in the Burningham image, where it says “vent” is where my vent tube will jog vertically up through the trunk to the high point.

 

A picture says a thousand words, zoom in on the trunk / back window:

image.jpeg.4bbb59acea831aa29b601ffa80b0125d.jpeg
(big thanks to sssquid tuning, 90racing.com, European Auto Garage, and Generations Pizza near Cincinnati for their support at INDY)

(I bought the rights to that photo but it’s a higher res version that I don’t want to burden the forum with, so that’s a Facebook grab. Photo credit: Ben Newburn)

Edited by enginerd
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1 hour ago, mhr650 said:

I believe Mender has the filler on the front cowl for his Fiero.

Yes. I put it there because I wanted to use a funnel to make sure there was no fuel spillage, and it worked.

DSCI0007.JPG.c5f9833bc6aed46b86ab4852efa6a67c.JPG

I used a NASCAR vent/valve as well:

DSCI0004.JPG.0d27bb4371a98c78ca734ee674b79c0b.JPG

And put the outlet right beside the fueler so he could see any overflow. Also, easy to place the catch can on it or the catch pan under it.

DSCI0005.JPG.44797499610d9ae3754b52767ce1b666.JPG

 

Now that funnels aren't allowed, I guess I'll swap it out for a dry break on some Hunsaker jugs so I can dump 4 cans in about 30 seconds. :)

Edited by mender
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On 2/22/2021 at 6:25 AM, shutupracing said:

Any chance you could share some pictures?

 

Paint is drying in the rear now and im leaving for a tarpon fishing trip tomorrow. I will be happy to slap some up when i get home next week and have it installed.

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19 hours ago, Bandit said:

Any cars that can't meet that?

Boxsters with a cell would have a hard time with that (tank in the front),  unless you run the fill neck through the cabin and around/above the motor. 

On the plus side, you gain a little extra capacity?? hahaha

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1 hour ago, tyler_j said:

Boxsters with a cell would have a hard time with that (tank in the front),  unless you run the fill neck through the cabin and around/above the motor. 

On the plus side, you gain a little extra capacity?? hahaha


Yeah but a boxter doesn’t need the capacity. 

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One thing I don't think has been mentioned. You should size your cell a couple of gallons larger than you want the actual capacity to be. I've noticed say a 22 gallon cell.  You add an in cell pump, lines, a catch can, and some safety foam and you lose some capacity. Some of the types of foam are more dense and take up more room. A 22 gallon cell can actually only hold 20.5 gallons. I think the cell sides also bow in a little bit reducing capacity. The EVO I was crewing for a couple weeks back had a 24 gal cell and it only held 22.5 gal.

Edited by Dimsun Racing
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Any idea why 3" OD tubing is even allowed?  If you stayed with 1-1/2" or "no bigger than OE" it would not provide much advantage and stop people from trying so hard.

 

Otherwise a re-write like this - fuel filler location is allowed to be moved.  Total length of filler tubing from gas cap to fuel tank must not exceed 75% of the width of the car.

 

Or 80%, or 90%, I need to go measure what is actually reasonable to make a 180 bend, get across the car and up to the filler.  Pretty easy to look and see if someone is pushing the limit, and if they are, a tape measure isn't too hard to drum up.

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13 hours ago, MMiskoe said:

Any idea why 3" OD tubing is even allowed?

 

 Total length of filler tubing from gas cap to fuel tank must not exceed 75% of the width of the car.

 

Agree with you on a total length restriction. But the reason they give you 5 minutes for a pit stop is so you don't rush. With the smaller size fueling diameters you end up rushing because it takes longer to fuel and leaves you less time to get the driver in the car and situated. This has become more of a problem with faster cars that need more fuel.

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13 hours ago, MMiskoe said:

Any idea why 3" OD tubing is even allowed?  If you stayed with 1-1/2" or "no bigger than OE" it would not provide much advantage and stop people from trying so hard.

 

Otherwise a re-write like this - fuel filler location is allowed to be moved.  Total length of filler tubing from gas cap to fuel tank must not exceed 75% of the width of the car.

 

Or 80%, or 90%, I need to go measure what is actually reasonable to make a 180 bend, get across the car and up to the filler.  Pretty easy to look and see if someone is pushing the limit, and if they are, a tape measure isn't too hard to drum up.

 

It was to reign in the 6+ inch filler pipes that some people were running since there was no rule at the time.

 

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