fuel cell delima

[r lane]

I run a 17 gal fuel cell in my car, 78 911. It is out of date according to NASA and I need to replace it. The bladder is $1900, and in the scheme of the cost of racing, maybe not shocking, but I could also install a standard fuel tank which I have and that is accepted by NASA. So 2 concerns, In a front end collision, the bladder is less likely to rupture. I had also built sort of a roll cage around it. So you have that benefit. #2, something I have wondered, does the cell have baffling. Does it stabilize the fuel. If you have 10 gal of fuel, approx 60 lbs thrashing about in a 20 gal stock tank, what effect does that have on the stability of the car. If in fact it does, then not a bad price for handling enhancement. Would like to hear what you guys know. Bob

[Mahler9th]

My race car is based on a '75. It has a 3.6 and I used it for sprint racing. I use a Fuel Safe Enduro cell.

A bunch of us in my area have used these rectangular cells.

When we ran under NASA sanction (Porsche Racing Club) we had a fuel cell rule that was different from NASA CCR.

Seems CCR now limits bladders to five (5) years.

Not clear whether this makes sense for the FS Enduro-style bladders.

[stownsen914]

Seems every club does it a little differently. Some say replace, others require inspection. If inspection is an option, at a minimum most replace the foam and, look for any degradation of the bladder, and fill with water to check for leaks.

Recertification was an option at one time, not sure about now.

[Tom '74 911]

I can't answer all your questions, but will relate my own experience for another data point for you...

My race car has a Fuel Safe fuel cell, which was one of the very few systems I did not go through when I bought the car. A few years into ownership, I had an event where I noticed a strong fuel smell when on-track. While doing my post-event inspection, I found fuel/oil streaks all along the bottom of the car and a really strong fuel smell from the front trunk area. I pulled off the fuel cell lid and found the bladder had significantly disintegrated and was leaking badly - see attached photos! I feel like I got away with one there... could have lead to a pretty bad situation.

My take away is that fuel cell bladders do actually time out. Mine was likely really old - 5 years seems like a short replacement interval, but probably not a short interval for inspection... I don't remember how much the new bladder cost off hand, but like seats and fire suppression systems and tires it's just the cost of doing business when you own and race a car...

Mine is 100% filled with foam, so very minimal sloshing. I am not nearly a good enough driver to notice the weight of fuel sloshing around...

Hopefully some of that is helpful...?

Best,
Tom

[r lane]

Thanks for all the input. Considering the stupid money one spends on a race car, why quible over something as significant as your fuel container. It just caught me out a bit as I had not prepared for that particular expendature. A friend related an incident in which a 911 center punched a pole. Pushed half way into the cell. Had it been a conventional tank, maybe Kaboom. One never thinks he will wreck and I hope I never do, but. So its ordered. Bob

[jmz]

There is a shop that will do the bladder for less but you have to ship to CA. …name escapes me but I will post later.

The 911 fuel tank is pretty damn safe so I would not have an issue racing with the factory tank.