Aluminum Gas Tank Fab

[Yummi]

Far northwest corner.  Area before ranger station about 1/2 mile off 78 and west of gecko road.  Hard pack, (well except the spot Fast and I found last trip)  in a little hollow, no dust as it is farmland to west and prevailing winds.  Just across the road from the bigger bowls.  Don't know why more folks don't stay there other than crossing gecko road?

[fabr]

Is there a problem/issue with crossing Gecko? Of course you guys like big bowls so that would make sense to move camp there I suppose.

[Yummi]

No - cross just fine.  Traffic is only issue. But what?  three crosses each way a day worst case?  No worries.   

[fabr]

Traffic is that heavy on Gecko? LOL!!!! I assume you can cross anywhere you want?

[Yummi]

Yes, and suprisingly there can be a bit of a wait right there.   Not good visibility, etc. 

[fabr]

Wow,had no idea of that.

[WelderPat]

Did I mention I will need 2 tanks. One flanking each side of the mid engine. That will keep the weight further back,low as possible and balanced side to side.  Going to run E85 so I plan on carrying a minimum of 40 gallons-20 each tank.I'm just a wanna be baller. LOL!!!! I can't justify $10K for tanks. I can though build the best tank I can though with good baffling and foam.

 If you can't get two twenty gallon fuel tanks made for a thousand dollars you are talking to the wrong people.

[Yummi]

^^^^  "Who ever labeled me GRUNT WORKER can kiss my #%^*"

What about the person that changes it to "HERO MEMBER?"  What part you gonna kiss to show your thanks?

[fabr]

If you can't get two twenty gallon fuel tanks made for a thousand dollars you are talking to the wrong people.

IF you had read the thread you would know that referred to 2 custom fuel cells like FuelSafe makes. A standard FuelSafe fuel cell is around $2k minimum . Customs go up in price extremely fast. Alll depends how safe you want to be and how much you're willing to spend. Remember the early days of Nascar,Indy and LeMans,etc.? Nearly every crash resulted in a massive fire and injury/death. Fuel cells like FuelSafe makes have nearly eliminated that risk. Even local roundy round racers now ,many times, are required to run REAL fuel cells in the interest of safety.

[fabr]

Pat,you are a professional welder I think. What is your opinion on the weld joint? Butt or lap?

[WelderPat]

Just curious. It seems like we all just butt joint and weld seams in an aluminum gas tank. I've always been a bit skeptical whether or not that is the best method. Many times tanks fail at the welded butt joint seam over time. Does anyone have a better way? 

If working with .090 or .125 ally which would be better , the left or right fit up before welding?

 The one on the left is the correct way. The weld can grab the entire thickness of the material.
The weld should have a radius equivalent to drawing an arc that was centered on the inside corners and conected the outer corners, if the weld is flat across the two outer corners it is to thin.
 3003 welded with 1100 rod gives you a tank that is very ductile and less prone to crack.
Keep ALL fitings on the top of the tank where a leaking hose ,or ,fitting wont allow all of your gas to just drain out.
 Cut a four inch hole in the top of the tank and fill the tank with foam.
 Cut a six inch disc drill it and tap the tank to seal the hole,use lots of sealer on this, sealer good,fire not good,sealer cheap, fire not so cheap.
 When the tank is all done pressurize to three p.s.i., if it holds pessure for ten minutes you are good,if not find out why and fix it.
 Don't carry more gas than you need, If you have a twenty gallon tank with eighteen gallons in it if an impact crushes the tank reducing its capacity to ten gallons the hydraulic pressure is almost unstopable, Eight gallons are going somewhere.
 Keep the vent as big as possible to vent the pressure in a wreck,put a filter on it to keep the crap out,place it where you would want the fumes ,and possibly fire to go,probably not at your noggin.

[WelderPat]

^^^^  "Who ever labeled me GRUNT WORKER can kiss my #%^*"

What about the person that changes it to "HERO MEMBER?"  What part you gonna kiss to show your thanks?

 That puts me very overrated.

[Carlriddle]

Great answer Pat!!! 
On sealant, anything recommended from those that know.  My fuel gauge sending unit still has a slight leak.  Gas proof thread seal on bolts, and its an oring seal on plate. 

[fabr]

The UltraGray silicone made byPermatex or Loctite will never be affected by gas or oil and it blends nicely in color to aluminum.

 Pat, thanks for the answer. As a professional welder your opinion is greatly appreciated. Is the offset  lap joint a bad way to go?

[fabr]

When fabbing tanks I use the "fuel cell" fill fitting and that allows the foam insertion/removal without the need for a separate "stuffing port" as Pat described. Very glad Pat mentioned the foam. VERY important to fuel control in an accident. Baffling is fine but you still need foam in the tank. If running fuel with ANY alky in it be sure the foam is alky proof.