Seeking metallurgist
Discussion
Its a complex subject so I would recommend that you only get an aluminium tank fabricated using a professional sheetmetal work company.
To answer your question though the material that would be best suited in my opinion to fabricate your tank is a 5xxx series alloy. These alloys have very good corrosion resistance and are used for harsh and sea water applications for example in making boats. I would consider being tucked away under a wedge for a few years quite a harsh environment.
A commonly used material is 5083 which is easy to obtain and has a high magnesium content. This could be used for the actual fabrication of the tank. However, the tricky part is that tubes and pipe outlets for joining your two tanks together plus the filler neck etc would usually have to be from a different alloy/material. This is because 5083 is not usually used for extrusions etc like tube/pipe.
The 6xxx series alloys are used for extrusion though but these are heat treatable and can be tricky to work with. Alloy 6061 is available in tube form and can be welded to 5083 relatively easily. As long as the correct fabrication and welding procedures and filler wires are used the tank could last longer than the rest of your car. There are a few choices of welding wire but filler wire type 5356 which is available for both mig and tig welding would be ok. Dont bother polishing the tank if your fabricator uses 5083 though because the high corrosion resistance comes about because of the heavy oxide layer that is formed naturally on this material.
Of course if you want a polished and shiny tank thats a different matter and there are other materials that shine but they are not as corrosion resistant as what I have suggested but you asked for the best material.
To answer your question though the material that would be best suited in my opinion to fabricate your tank is a 5xxx series alloy. These alloys have very good corrosion resistance and are used for harsh and sea water applications for example in making boats. I would consider being tucked away under a wedge for a few years quite a harsh environment.
A commonly used material is 5083 which is easy to obtain and has a high magnesium content. This could be used for the actual fabrication of the tank. However, the tricky part is that tubes and pipe outlets for joining your two tanks together plus the filler neck etc would usually have to be from a different alloy/material. This is because 5083 is not usually used for extrusions etc like tube/pipe.
The 6xxx series alloys are used for extrusion though but these are heat treatable and can be tricky to work with. Alloy 6061 is available in tube form and can be welded to 5083 relatively easily. As long as the correct fabrication and welding procedures and filler wires are used the tank could last longer than the rest of your car. There are a few choices of welding wire but filler wire type 5356 which is available for both mig and tig welding would be ok. Dont bother polishing the tank if your fabricator uses 5083 though because the high corrosion resistance comes about because of the heavy oxide layer that is formed naturally on this material.
Of course if you want a polished and shiny tank thats a different matter and there are other materials that shine but they are not as corrosion resistant as what I have suggested but you asked for the best material.
ferlin said:
Its a complex subject so I would recommend that you only get an aluminium tank fabricated using a professional sheetmetal work company.
To answer your question though the material that would be best suited in my opinion to fabricate your tank is a 5xxx series alloy. These alloys have very good corrosion resistance and are used for harsh and sea water applications for example in making boats. I would consider being tucked away under a wedge for a few years quite a harsh environment.
A commonly used material is 5083 which is easy to obtain and has a high magnesium content. This could be used for the actual fabrication of the tank. However, the tricky part is that tubes and pipe outlets for joining your two tanks together plus the filler neck etc would usually have to be from a different alloy/material. This is because 5083 is not usually used for extrusions etc like tube/pipe.
The 6xxx series alloys are used for extrusion though but these are heat treatable and can be tricky to work with. Alloy 6061 is available in tube form and can be welded to 5083 relatively easily. As long as the correct fabrication and welding procedures and filler wires are used the tank could last longer than the rest of your car. There are a few choices of welding wire but filler wire type 5356 which is available for both mig and tig welding would be ok. Dont bother polishing the tank if your fabricator uses 5083 though because the high corrosion resistance comes about because of the heavy oxide layer that is formed naturally on this material.
Of course if you want a polished and shiny tank thats a different matter and there are other materials that shine but they are not as corrosion resistant as what I have suggested but you asked for the best material.
What an excellent answer! WoolyTo answer your question though the material that would be best suited in my opinion to fabricate your tank is a 5xxx series alloy. These alloys have very good corrosion resistance and are used for harsh and sea water applications for example in making boats. I would consider being tucked away under a wedge for a few years quite a harsh environment.
A commonly used material is 5083 which is easy to obtain and has a high magnesium content. This could be used for the actual fabrication of the tank. However, the tricky part is that tubes and pipe outlets for joining your two tanks together plus the filler neck etc would usually have to be from a different alloy/material. This is because 5083 is not usually used for extrusions etc like tube/pipe.
The 6xxx series alloys are used for extrusion though but these are heat treatable and can be tricky to work with. Alloy 6061 is available in tube form and can be welded to 5083 relatively easily. As long as the correct fabrication and welding procedures and filler wires are used the tank could last longer than the rest of your car. There are a few choices of welding wire but filler wire type 5356 which is available for both mig and tig welding would be ok. Dont bother polishing the tank if your fabricator uses 5083 though because the high corrosion resistance comes about because of the heavy oxide layer that is formed naturally on this material.
Of course if you want a polished and shiny tank thats a different matter and there are other materials that shine but they are not as corrosion resistant as what I have suggested but you asked for the best material.
portzi said:
well firstly make sure its weldable as alot of ali specs you can't. I am sure the company you buy the ali off will be able to tell you, what you need for a fuel tank. then you just need a good tig welder.
You can usually MIG weld alloys and is a faster process than MIG, TIG is better if you want a glorious finish but would probably be wasted on fuel tanks 
However if your MIG is not set up for alloy you'll need Argon as a shield gas and you'll probably have to at the very least fit a new torch liner and torch tip.
Disposable bottles of Argon are about as cost-effective as buying lotto tickets, in which case you're probably into a contract with BOC or Air Products - some folk are lucky and have independent suppliers locally who will do a rental-free bottle but they're few and far between.
Some MIG sets are capable of running a spool gun and for small jobs this is the preferred method for a lot of fabricators - instead of a normal MIG set you have a different torch with in-built motor drive that takes a small spool of filler wire; the short distance from spool to tip means it has no room to kink unlike when trying to force it up 4m of standard torch hose. However you'd either have to have a more professional MIG set or be prepared to get into electronics to convert your existing one to take a spool gun.
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