my 33 humpback panel truck will require a custom fabbed gastank, but cousin charlie's model A rpu. is at the stage he needs a tank fabbed to complete his build[well, a buddy and myself are really building the chassis for it.....] before the paint can be applied to the chassis. my question is this. what material should i fab this from ? i have been leaning toward 16ga. stainless, but would also consider aluminium and possibly coated steel. other than the obvious welding differences, anything i should consider to base my decision on ? i will be making the pattern from cardboard as it must fit a pretty tight space. i'll do his first, so incase i goof up the first time, he can buy more material. baffels will also be included as necessary. thanks in advance !

I've always seen them out of Aluminum. probably cheaper material and less corrosion potential.

stainless would work just as well, would be harder when finished.

both materials could be polished to a mirror like finish when done for a truly custom look

I would stick with steel or stainless steel. I would not trust aluminum. First if you back into something parking or in a crash it will tear easily, second I saw first hand the remains of a Ferrari 458 that burned as a result of a engine compartment fire. There was NOTHING left of the aluminum and magnesium parts, from upper control arms, frame rails, to the intake all the way up to the windshield BUT the steel fuel tanks were intact. That made up my mind no aluminum fuel tank on my 56 Dodge.
Scott

interesting thought about crashworthyness of aluminium. on my humpback, the tank will be protected by the chassis members, but on charlie's model A rpu, it will be attached to the chassis below the bed floor. i'm leaning toward stainless, but i wonder how thick the material is on the aluminium tanks i've seen ? out of curiosity, how thick are the "poly" tanks used in new cars ?

Most aluminum and poly tanks I've seen were about 1/8" thick. If you consider an 1/8" sheet of aluminum with bracing (baffles) with the short dimensions of a fuel tank, that 1/8" aluminum is pretty tough. I've sen aluminum tanks with pretty deep gouges in them that never leaked a drop. There is a better chance the aluminum tank will crack from road vibrations long before any other issues will likely happen, and that event is several years down the rough roads. The biggest issue with the poly tanks is also cracking from vibration.

As far as melting a fuel tank, if the fire gets hot enough to melt a fuel tank, everything else would be toast by then, the melting tank would be a mute point. Consider the fact that before the aluminum can melt, it has to reach 800 degrees. That would mean everything surrounding the tank also has to be very close to that 800 degrees, including the air inside and outside the tank. The fuel inside the tank also has to reach 800 degrees before the aluminum can melt. Any material or plastic in the car would be burned up long before that happens.

That said, when
I build my tanks, I build them out of 14 gauge steel. I'm cheap and aluminum is expensive. Gene

gene, do you use a coated steel, or just plain hot/cold rolled ? if just a plain steel, what kind[if any] of problems with internal corrosion[rust]?

Plain old mild steel. The last tank I built has been in use for 5 years now and as far as I know there have been no issues. The one before that has been around over 15 years without issues. Sitting around not being used for years, 1/2 full, is what promotes rust and other problems.

I would be a little concerned about coating the inside of a tank these days, this stuff they are selling us they call fuel has proven to cause reactions with many of the tank sealers from even a few years ago. I don't think they are done messing with the fuel yet, I expect it to get worse. As long as the new car manufactures keep making tanks from steel, (though they are galvanizing them) I think we will would be wise to do the same. Gene

i agree 500% on the sealer issue. i haven't been a fan of that stuff for years, and you are correct; the fuel formulas will be changing for quite a long time i'm afraid.........

Without climbing under the car, I'm pretty sure out 2004 PT has a steel tank, but really, I haven't recently looked. I don't spend much time under new cars. Gene