Thread: Trunk Mounted Gas Tank Fire Wall

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With a trunk mounted gas tank do you worry about a firewall between the trunk & interior? If yes, is there an excepted way for sealing off the trunk area (with gas tank) from the interior area on a glass coupe? My body has 1" square tube bracing, angled back about 15 degrees from vertical. Sheet metal panel to fit, silicone sealed all around? How about MDF board? Not looking to block a fire for any length of time, just contain a tank rupture away from the passenger area to allow time for exit/rescue in the event of a collision.

So no thoughts on interior firewalls from those who've been down the path before? I'm not trying to shift responsibility here, just looking for ideas on approach, or if it is not even something to consider...

I was going to respond earlier Roger, but didn't because although I am running a similar setup in my 27 I don't have the metal pan between the trunk and cockpit, mine is fiberglass and wood.

But, there should be no magic to this either way. All you want to do, or all you CAN do is try to seal off the bulkhead as well as possible to give you as much protection against splashed (in a rear end collision) gas as possible. I think we all remember the Pinto gas tank situation, but in reality very few cars from that era had better protection. Look at where a stock 32 gas tank sits, right back where a rear ender would smash it.

If it makes you feel better you could do the caulk routine and possibly lay a layer of some fire retardant sheeting over it. Not sure what that sheeting would be, but if you cruise the aisles at Home Depot you might find something suitable.

In reality though, most of our cars are vulnerable if some SUV rearranges our backside. My 23 has 11 gallons of high test sitting right where a high bumper would smash it and toss gas all over me, I'm sure. We have very little protection from some of the monster trucks running around on the roads.

Don

I would maybe attack the problem from a different view.

Your thinking is to prevent the "fuel splash" from getting into the interior after the crash, which is a very GOOD idea.

But, how about doing more to keep the fuel contained "inside the fuel tank" during the crash? Fuel foam will reduce the fuel from sloshing out of the damaged tank after the crash. It does not have much reduction to the volume of the tank. Look into what is available from the fuel cell suppliers. They sell it in blocks that you squeeze and slide it into the tank through the filler. We have it in our VW drag car which has a small aluminum tank mounted "up front" which IMO is an even worse location than being hit from behind.

there is no good protection from a trunk mounted fuel tank---with numerous areas for leakage, damage from crashes, hell just static electricity(remember that in a fiberglas body you don't have all the grounds from metal to metal mounting)---

Put the tank under the car-----

mercedes benz put the fuel tank behind the rear seat on many of the cars made in the late 70's- mid 80's. they did however, use a fairly thick firewall directly behind the seat, and a cardboard interior panel behind the tank. the tanks stand up vertical and are bolted to the firewall.. 240D/300D ( diesel models ) and the 230C/280C/CE ( gasoline models ) all use that configuration

That is an excellent idea about the fuel cell foam.........Summit and others carry it. Supposedly it doesn't work well with ethanol though as it attacks the foam. Hard to buy gas anymore without some ethanol in it.

Don

I have a frame/trunk mounted fuel cell, really in the fram but half in the trunk. I used bady sealer and rivits for mine. I have a foam filled one. main reason I did it was for the fumes and in case I was required to. while my car is stel, I think the principal idea would be the same. just make sure and vent it properly to the outside