Shavarsh
Shavarsh Reader
4/29/21 10:23 p.m.

Hello All,

I have recently been faced with the decision to modify my stock gas tank or get creative and use a fuel cell. I think its a good point of discussion. So, what do you think about the safety of a stock tank vs a fuel cell in a street car? Specifically I am interested in rear mounted cases. The way I see it the benefits/disadvantages are as follows.

Benefits:

 

Stock tank:

-It fits

-Safe enough to be produced by the OEM (and pass DOT standards)

 

Fuel cell:

-More robust fuel containment upon impact

 

Downsides:

 

Stock tank:

-More easily ruptured in a crash leading to fire

 

Fuel cell:

-Packaging (body modification often needed)

-Filling (remote fillers take up trunk space/filling inside the vehicle will lead to spills/fumes)

-Maintenance (bladders and foam need to be kept up to date)

 

For the sake of argument lets assume there is no firewall other than the trunk floor in the rear of the vehicle (aka my pinto :)). Thoughts?

Tom1200
Tom1200 SuperDork
4/29/21 10:57 p.m.

So I've had two street driven cars with a cell in them.

My Baja Bug had one on the rear shelf; it was not particularly well mounted but that was an easy fix. Dragging the fuel hose into the car was a bit of a pain.

My Datsun was street driven for a while and the stock fuel tank location is under the trunk floor. The cell is mounted in the same position and is safer than stock tank but if the stock tank was mid mounted I think that would be safer than the trunk mounted cell.

One of the thing that makes fuel cells potentially less safe is the fuel neck arrangement. When I was involved in rally there was a huge debate about how the filler necks were done. In some cases the filler neck arrangement made the cell less safe then the stock tank.

Mostly I find having a cell in a street car comes with some level of inconvenience.

Shavarsh
Shavarsh Reader
4/30/21 11:56 a.m.

Tom, 

how is the filler set up in your Datsun? Does it come into the top of the cell or the side?

Tom1200
Tom1200 SuperDork
4/30/21 12:00 p.m.

I just open the trunk and fill it, no filler neck.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
4/30/21 12:31 p.m.

Fuel cells are a huge pain in the ass.  The cheaper ones (meaning, the ones most common to see) usually have a difficult to open filler, they vent to the local atmosphere, and they aren't any "safer" than a stock tank, they are just plastic shells.  Probably less safe, because of the easy-to-break-off fittings on the bottom.

 

I'd only consider a cell if it could be engineered to use the stock filler neck and retain the evaporative emissions system.  Not just because that's the kind to the environment thing to do, but I've found that fuel goes stale quickly if you do not have a working evap system.  Fuel also just plain disappears when the car is parked, that's money being thrown away.

L5wolvesf
L5wolvesf HalfDork
4/30/21 12:59 p.m.
Shavarsh said:

I have recently been faced with the decision to modify my stock gas tank

WHY?

Stock tank: -More easily ruptured in a crash leading to fire

Is this specifically in reference to the Pinto fire issue?

Shavarsh
Shavarsh Reader
4/30/21 1:34 p.m.

In reply to L5wolvesf :

I figured for this discussion thread I would leave it as a general topic. In my specific case I no longer have the space I had before for my gas tank without narrowing it. The addition of IRS and rear bumper support has shrunken my available space.

L5wolvesf
L5wolvesf HalfDork
4/30/21 5:00 p.m.
Shavarsh said:

For the sake of argument lets assume there is no firewall other than the trunk floor in the rear of the vehicle (aka my pinto :)).

Do you have the hatchback or the small trunk version?

Either way - if the cell goes back there make a firewall.

Shavarsh
Shavarsh Reader
4/30/21 5:09 p.m.

In reply to L5wolvesf :

I have the hatchback, at this point I am leaning toward just narrowing the stock tank and putting plastic shields around it. It will be under the trunk floor.

 

Anyone else with experience living with a fuel cell on the street, or thoughts on the safety benefits of using one?

Tom1200
Tom1200 SuperDork
4/30/21 5:38 p.m.

There really isn't a benefit other than you need the cell for the track. My Baja Bug had it when I got it and for the Datsun I needed it for racing.  

I wouldn't bother in a street car. 

Shavarsh
Shavarsh Reader
5/21/21 2:04 p.m.

Ok, new question. I am going with a steel shell/plastic-tank cell with remote fill to the stock fill location for this pinto. I am struggling to find a size that will fit and hold over 10 gallons. The manufacturers on my radar are as follows:

Jaz

RCI

Summit/Jegs

RJS

The question is, am I missing another manufacturer in this price range? I know about ATL and Fuel Safe but they are higher dollar than I am willing to consider.

 

Separate Question: I have been avoiding rear sumped fuel cells because this car will be mainly used for street/canyon driving and I do not want to run into starvation issues on the brakes. Does anyone have relevant experience/ advice on this?

 

Thanks

 

wearymicrobe
wearymicrobe PowerDork
5/21/21 2:26 p.m.

Seems like a cheap swirl pot would fit the sumped fuel cell but at a high cost. My cell also leaks a bit when you get fuel up into the very long neck required to get gas into the back of my baja bug. You will get gas stuck in there. Add in the new filler cap and all the prep and stock tank always looks better to me. 

 

We have talked but I think a bigger stock tank is better then a fuel cell for most applications. You can build a splash shield for the stock tank really easy with your skills. 

Tom1200
Tom1200 SuperDork
5/21/21 7:08 p.m.

In reply to Shavarsh :

Unfortunately I'm no help on this as I have to run an FIA certified cell. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/22/21 7:34 p.m.

Is there any chance you might be able to raise the floor and use a Wrangler tank?  They're fairly narrow and short, but tall.

Shavarsh
Shavarsh Reader
5/24/21 10:56 a.m.

In reply to Pete. (l33t FS) :

Pete yes, I could raise the floor but I'd rather not. I need to verify a couple things with Jaz but I'll likely be using their 12 gallon cell. The dimensions (18.5x16.5x10.5) are the maximum in height and width I can fit. The plan is to move the fill neck to the side of the lid and attach it to the stock fill location.

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