Ok. i know most of you are stateside...
but...i'm looking at setting something up like this.



I'm sure most know how a surge tank works, but i'm looking at the following set-up.

Stock OEM Subaru Fuel Tank
->OEM Fuel Pump feeds/fills the Surge tank
->Surge tank located in the trunk which is always full feeds the main pump
-> Main pump through filters to engine

->Return line from engine feeds into the surge tank
->"overflow line" from surge feeds into the OEM tank.


The idea is it will let me suck the 60L Subaru OEM tank almost completely dry, and let me comfortably make the distances required between fuel stops. And add probably 5-6 l capacity.

Apparently CARS is using a formula for fuel consumption which is GREATER than what we consume, but assuming an 80L tank. And we get the cut-eye because we are running on Ethanol, and that's where our problem is (it's not!), or we need to spend big bucks on a Fuel cell.


CARS regs say
-that aftermarket tanks must be FIA/SFI approved.
-lines inside the cabin must be metal cased.
-supplemental fuel tanks are not allowed.
-if the fuel pump is inside, it must be separated by a flame proof firewall.


Would this even be legal?

What measures am i going to have to take?

Is sealing off the trunk area of the car with aluminum panels, and rivets enough? Or do i have to use some sort of sealant underneat everything and make the trunk absolutely air tight to the passagers cabin?

Can i fab up my own fuel tank? or do i have to purchase a custom made FIA/SFI approved cell...for probably more than a main cell for the car is worth.



I don't want to install a fuel cell. I don't like the ones that go in the trunk, they are too high in a subaru, and too far back. The OEM tank is placed well, and works. If i needed to do a cell, it would be 2 cells on either side of the drive shaft, and generally further complicate things...

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Chris

I'm pretty sure this falls under "supplementry fuel tanks" so you're SOL. I don't know how you're gonna make the long leg at PN.

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Gone fishing

Chris,
Why don't you run this past your regional scrutineer or CARS Technical Director Ivan Butikofer?

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First Rally: 2001
Driver (7), Co-Driver (44)
Drivers (16)
Clerk (10), Official (7), Volunteer (4)
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Last Updated, January 4, 2015

Quote
john vanlandingham
Blame is for idiots. losers.

I actually don't know how a surge tank works (or why), feel free to edumacate.

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Jon Burke - KI6LSW
Blog: http://psgrallywrx.blogspot.com/

Keith....

send ivan a note a couple days ago.

seeing what y'all think in the meantime.

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Chris

I did not have a good reply to a similar issue.

I asked if I could build a metal tube/jacket into the trunk area. I wanted to relocate the fuel filler tube out of the wheel arch. Even if I completly sealed the structure in and of itself, as well as building a fireproof bulkhead between the shock towers, I was told it wasn't something they could approve.

I'll see if I can find the response I got, I'll e-mail it to you if I find it.

you have an e-mail

Daniel,

I know exactly what you are talking about....

And i know of several cars which have exactly the set-up you are talking about, and they pass tech...

BIG names too...

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Chris

With the OEM tank? or a fuel cell?

I'm curious now!

you got a reply, and really it shouldn't matter.

some of what i'm talking about is in hatch backs....clearly open fuel lines to the passanger compartment, and filler necks...

You got an email with details.

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Chris

Overview of how it works

I understand how someone might think of the supplemental tank arguement....however not really sure why.

This would effectively be a sealed tank. I can see the reasoning behind another tank which has a separate filler, etc.



Plus the way this rule is written, you could not even run 2 FIA approved cells in the same car for packaging concerns.....

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Chris

Put a FRAM part number on the side of the swirl pot/surge tank. Then it's just a REALLY big fuel filter....

Bob

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Opel is a 4-letter word...
http://www.flickr.com/photos/10498579@N07/sets/

Or grab the main fuel pump assembly from a CIS engined VW. They had the exact setup you're thinking of making, and it's part of the fuel pump assembly.

Downside: It's only a liter of capacity, but you can still suck the main tank dry without worrying about getting air.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 12/18/2009 12:03PM by Pete.

I think both your situation and Daniel's fall under the 'can't mess with the stock fuel tank unless you install a cell' rule, with yours additionally falling afoul of the supplementary tank rule.

As far as big names with fillers in the trunk thing - I can't think of any big name types offhand who aren't running a cell?

I have the fuel cell, can and filler neck inside the pass. compartment of my VW ... (the cell is in a place least likely to suffer any sort of intrusion. The filler neck does not go out through a body panel to get deformed/breached when I hit a tree/rock with that panel and our fueling setup keeps the jugs outside)

Having said that, we're in the process of modifying this and another car to seal around the top plate & filler, come through a bulkhead to -12 braided fuel and vent hoses with refueling through a sealed quick-disconnect (virtually a dry break give or take a drop of fuel at the moment of disconnect - valved at both ends, fully servicable). We started doing this when we were looking at running in the U.S. and had some discussions with scrutineers etc.

At PRI we talked with Staubli and a couple of other suppliers. Staubli makes the dry breaks that all the WRC teams (and others) use - really nice, but expensive - not really within the budgets of most of us clubman-types. We think a better solution is a sealed quick-disconnect - we've made a deal with a supplier and we're in the process of bringing some of these in. We have an order of -12 and -6 arriving next week. They'll be available through Hot Bits and a couple of other rally shops in Canada.

If anybody's interested in the hardware, send me a msg robin at hotbits dot ca and I can give you more details.

As far as fuel cell vs. fuel tank, I remember at Perce Neige in 2001 or 2002 a Rabbit rolled upside down - stock fuel tank - gas everywhere - sloshing around the floor as they towed it out to the end of the stage. When Andrew Miller rolled Peter Reilly's AWD Golf at Rocky (with the same fuel setup as I have now) not a drop anywhere. Anecdotal - but hey.

Robin