Custom Gas Tank - Looking for some feedback

[Xusia]

Greetings Gents!

As many of you know, I'm planning on building my own gas tank. I have the shape and location dialed in (mostly, anyway), but I have some area I'd like to get opinions on from those of you with more experience than me.

Aluminum vs. Steel: Forget weight. I don't care. What is the better material? I'm inclined to go with steel for the price. I would only want to spend the extra on aluminum if there is a really good reason to do so.

Flat Bottom vs. Slanted: Slanted would reduce the capacity slightly, but direct more of the available fuel to the pickup. Worth doing or not? It adds a bit of complexity, and I'm not sure it's really worth the effort.

Fuel Pump Location & Pickup/Filter: Does the fuel pump need to be in the tank? I'd rather put it in the engine bay (along with the filter; next item). As long as I have a filter before the fuel pump, does it need to be on the end of the pickup? Does the pickup need to come from the top down? Could it come in from one of the sides? The tank will be up front and center, so what I'm contemplating is putting the pickup in from back of the bottom of the tank, pointed straight toward the engine. Then I run a fuel line down the center tunnel to the filter and pump in the engine bay. Would this work or not? What problems might I have?

Collector: I was already planning on building a small "dish" in the bottom around the pickup to prevent fuel starvation. How big/tall should it be? Is it worth getting a couple of those trap door thingys for $30 each (plastic) or since I'm not racing can I just rely on some holes (they would be small enough to significantly slow drainage)?

Anything other ideas, suggestions, or opinions?

Thanks everyone!

[metalmaker12]

Aluminum does not spark or rust. In general I believe the pump is safer in the tank.

[Santiago]

I think if you take a look at most tanks offered, you'll get some sense of what range of options have had the bugs worked out of the successful designs.

That makes steel or aluminum viable options. Steel is stronger, so you're likely to get a bit more crash protection (for similar concerns, you might consider foam blocks inside). I still prefer aluminum though - that whole no sparky no rusty thing is no small matter.

Pumps in the tank are also often done to simplify packaging and lower the noise level in the cabin. External pumps are not uncommon, and aside from their noise I don't know of any common concerns.

Fittings can be run at the bottom of the tank; this is how many of the non-certified off-the-shelf type fuel cells are made. My worry with those though is that if your fuel line loosens up or otherwise develops a leak, then the whole weight of the fuel load is there to offer a gravity-fed leak. If your fittings are on top and the same happens, at least the bulk of the fuel stays in the tank (except what might escape via pump pressure).

Most tanks and cells I've seen are flat bottom unless packaging requirements dictate otherwise. That is, cells are typically rectangular unless you need more volume and can only get it by squeezing in a bit more of the tank into some small space available to you.

Just some thoughts.

Best,
-j

[Canadian818]

If you hack the FFR tank you can re-use the subaru pump setup. Aeromotive makes a nice intank setup, foam baffle ext, but it's almost $500. I'm cutting the FFR tank to fit my seats, and I'll just seal it with por15 tank sealer.

[Xusia]

I think if you take a look at most tanks offered, you'll get some sense of what range of options have had the bugs worked out of the successful designs.

That makes steel or aluminum viable options. Steel is stronger, so you're likely to get a bit more crash protection (for similar concerns, you might consider foam blocks inside). I still prefer aluminum though - that whole no sparky no rusty thing is no small matter.

Pumps in the tank are also often done to simplify packaging and lower the noise level in the cabin. External pumps are not uncommon, and aside from their noise I don't know of any common concerns.

Fittings can be run at the bottom of the tank; this is how many of the non-certified off-the-shelf type fuel cells are made. My worry with those though is that if your fuel line loosens up or otherwise develops a leak, then the whole weight of the fuel load is there to offer a gravity-fed leak. If your fittings are on top and the same happens, at least the bulk of the fuel stays in the tank (except what might escape via pump pressure).

Most tanks and cells I've seen are flat bottom unless packaging requirements dictate otherwise. That is, cells are typically rectangular unless you need more volume and can only get it by squeezing in a bit more of the tank into some small space available to you.

Just some thoughts.

Best,
-j

Wow. Good stuff in there. Thanks! I think I like the idea of aluminum more now. I didn't think of rust. The outside will be painted, so no worries, but the inside won't be. I don't like the idea of metal flakes clogging my filter!

I also hadn't thought about leaks, but I think my idea would preclude that as an option. I was thinking of using a metal tube, welded in, with a recessed nipple on the outside. It would be no more likely to develop a leak than one of the sides (which would also be welded). I'll have to think on that some more.

If you hack the FFR tank you can re-use the subaru pump setup. Aeromotive makes a nice intank setup, foam baffle ext, but it's almost $500. I'm cutting the FFR tank to fit my seats, and I'll just seal it with por15 tank sealer.

My original idea was to cut a plate out around the cap on the FFR tank so that I could use the Subaru parts as FFR intended. And I could still do that. It just puts the plumbing up top. Since it will be visible under the front hood, I am in search of a more elegant solution. Also, after thinking about it, I'm liking the idea of an external pump & filter more and more. It just makes everything more easily accessible for maintenance, upgrades, etc.