CUSTOM WATER INJECTION TANK

For this project we needed to make a tank which fit a number of criteria. 

1. Needs to hold at least 5L of water.

2. Sit as low down as possible

3. Easy to fill.

4. Incorporate the WI Pump

5. Have an internal baffle 

 

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With all the measurement taken we now had to make a rudimentary shape to see how it fits, and how we can incorporate the pump into the design whilst keeping the capacity higher than 5L.

So with the criteria laid out we had to decide where to put the tank, we know we needed to make the tank sit as low as possible in the chassis so we decided to make use of the left sill. So, now we knew where to place the tank, it was time to measure up the space we had to work with 

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We came up with a couple of ideas, but nothing really struck us as "the one" .. Each idea was floored in one way or another, either it was going to be hard to mount, or hard to access the pump should anything go wrong.. 

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We finally stumbled on what looked like a good design so we made a to scale cardboard model and when we was happy with that we started cutting up metal with a rough idea of where we wanted to be.

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The first iteration of the tank didn't go too bad, we learnt a lot about the steps we needed to take to make it, having to think about what to weld, what to bend.. and in what order to do it all in. We opted to use 0.8mm stainless steel and controlling the heat was becoming an issue. 

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We took the time to use the first attempt to test fit on the car and make sure that the dimensions we were working to were still good. It was, we could of made it a bit larger still by opening the top up and creating sloped sides but we decided to leave it as is to save any further complications. 

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We decided to take what we had learnt and start again, this time making the design more modular, this allowed us to make it in parts and then, once each part was complete stick them together. We chose to make it out of 3 main parts, the body, which would incorporate the mounting for the pump, the lid which would have the filler neck attached and the swirl pot located right at the bottom which feeds the pump directly. 

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The main body of the tank was made by cutting out a shape and bending it, that way we only needed to make one weld join.  We used the lathe to make some inserts out of stainless steel, they looked like a top hat and sat into a hole and was welded in. 

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The water level sensor was next to design into the tank, we wanted to make sure that the G forces exerted on the tank were going to have the smallest effects to the sensor. so we created a little chamber for it to sit in, just big enough for it to operate but to keep water movement to the absolute minimum. 

 

When the tank is full, the senor floats breaking the signal of the sensor, as soon as the water level gets low enough the float will drop down creating a connection and alerting the driver to a low water level warning light.  

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The next part to tackle was the lower part of the tank, the swirl pot, a small container with limited space for the water to move, located as low as possible the only way the water can get in is via a 10mm hole just in front of the level sensor. This was done so the water that enters the swirl pot has a harder time finding its way out when cornering hard on the track. 

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Essentially, just a box with a tab bent over, it allowed us to weld it on with relative ease. we bent as many angles as we could to reduce the amount of welding needed. This also reduced the amount of potential holes in the joins.

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The lid was quite simple, trace around the top of the tank, cut a hole somewhere in it and weld a pipe in. invert the lid so the pipe it stick up and that is the filler neck which will have silicone tubes on. 

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All welded up, it was time to fill it and see how much water was lost over night. Happily, not a drop of water was missing the following morning. 

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Once the lid was cut to shape we put a hole in it, and rolled the edges of the pipe over so it would rest on the lid, this made for a very easy and strong joint for the filler neck.

The lid and pipe with 2 aluminium cooling blocks. 

Once completed we managed to compete all the criteria set out at the start. we have a completed capacity of just over 5L in the tank. We chose to use a wider filler neck and route the pipework up to the bulkhead, one for ease of filling and two to allow us to use that as part of the total capacity.. all told we actually have over 6L of water once filled to the top. 

Pics of the completed install are to follow.