Long range tank construction.

[Struth]

I am getting ready to build a long range tank for under the 4 Runner.

Basic construction is no worries, but are there any little tricks to these things, for example should they have baffles, should the pick up be a certain distance from the tank bottom, is the breather meant start in the fuel or in the air above the fuel, etc. Any other hints other than dont waste your time?

Plan ATM is to fit an internal pump connected to the engine fuel line and use one way valves to avoid each tank pumping into the other.

Cheers

[MICK77]

Let me first state that I am no tank builder. That said.

The breather should be as high as possible in the tank. It is there for air to flow through due to expansion / contraction of the fuel.

I think baffles would be a great idea certainly around the pick up so the pump never starves for fuel on an angle or rough terrain.

I would place the pick up around 25mm from the bottom of the tank. This will allow room under the pick up incase the tank is badly dented it won't block off the pick up. Also it will prevent crap being sucked off the bottom of the tank and through your fuel system.

Micko

[trains]

Ok

Yes you need baffles.

You need a small chamber that feed fuel into it, but when the tank is at an angle, not all of the fuel will escape, so you dont run out when climbing, decending at angle, thats where the fuel pickup sits, if your using factory pickup. 2-3 lts would be sufficient.
pick up can be right at the bottom of this surge tank.

Have a look at a cut away davies craig tank, or long ranger in an arb store for ideas.

Add a double gusset where you have a tank securing point.
Ie, if you have 2 bolts to hold it at say the back of the tank, add approx 1/3 the size of the back of the tank in steel welded to the tank, then weld your mounting points to that extra bit, it distributes the load much better.
You need to calculate the total size of the tank, and add extra for fuel expansion/ air space, so your tank wont vent fuel on the ground when full and the temp causes the fuel to expand.
Breathers should be at the very top of the tank.

brace the tank/ baffles work well at this and allow for flex at the mounting points, so the points flex, and the tank doesnt.

Now you wont have any problesm with welds leaking, as all your load is evenly distributed across the tank, and you will pickup just about all of your fuel.
Dont forget to fit a fuel / water drain at the very lowest point in the tank.

Trains

[Struth]

Sweet, thanks guys, good input.

Cheers

[ajsr]

Ok

Yes you need baffles.

You need a small chamber that feed fuel into it, but when the tank is at an angle, not all of the fuel will escape, so you dont run out when climbing, decending at angle, thats where the fuel pickup sits, if your using factory pickup. 2-3 lts would be sufficient.
pick up can be right at the bottom of this surge tank.

Have a look at a cut away davies craig tank, or long ranger in an arb store for ideas.

Add a double gusset where you have a tank securing point.
Ie, if you have 2 bolts to hold it at say the back of the tank, add approx 1/3 the size of the back of the tank in steel welded to the tank, then weld your mounting points to that extra bit, it distributes the load much better.
You need to calculate the total size of the tank, and add extra for fuel expansion/ air space, so your tank wont vent fuel on the ground when full and the temp causes the fuel to expand.
Breathers should be at the very top of the tank.

brace the tank/ baffles work well at this and allow for flex at the mounting points, so the points flex, and the tank doesnt.

Now you wont have any problesm with welds leaking, as all your load is evenly distributed across the tank, and you will pickup just about all of your fuel.
Dont forget to fit a fuel / water drain at the very lowest point in the tank.

Trains

I used to make tanks for brown davis and all the above is totaly correct also a good idea to put in a few spare bosses incase you wish to put in fuel transfers etc