3/12/06 Calculating the head pressure of the water pump

Using an unfeasible long piece of hose I made a DIY manometer to measure my head pressure. All I can tell you is that the pressure is between 4m/H20 and 6mH20 - this is because i didn't have a big step ladder to measure exactly where it got to. Which equates to about 5.5 to 8.5 psi. Neighbours took a dim view of 6 meters of steel waggling around over his car.

18/12/06 Calculating the head pressure the proper way

Obtained a 1 bar pressure gauge from ebay - brand new only cost £5.0 delivered. I made a little spigot so i can measure the water pressure easily, although i managed to knacker the gauge by grinding the brass fitting and now it reads out by 1psi.

The pump has a back pressure of about 6.5psi - and a stall pressure of 12 psi - Here's a short video showing how noisy the pump is: Click here

Sooo, if I fitted the Jabsco 50830 Pump - we can see that it should pump 38LPM at 6psi - which is 630cc of water per second, which means it would take only 6 seconds to pump 10 Litres of water into the cooler - which means it should drastically reduce the time to cool the Inlet after a hot restart.

24/12/06 Auxiliary Chargecooler Water tank Fabrication

So from my testing, adding 10L of water into the cooler provides a good stabilisation of inlet temperatures. The Dakar has two battery boxes, one of which is empty - so this was chosen to be the location of an auxiliary water tank, which is conveniently comes out at 10 Litres. The following sequence of photo's will show how I made a simple tank from aluminium without using shears or a folding machine. Examining my professionally made fuel tank I noticed two design features:

The main body of the tank is folded from one sheet

The end tanks have returns added which makes welding it up easier and the resulting tank is stronger. After making a cardboard mockup, I started with some 16 Gauge aluminium - I think the grade is NS4. I used a jigsaw with a very course blade to cut out all the panels. By clamping the metal between a think piece of metal, it was quite easy to bend the metal by hand - on the first bend I used a hammer to get a tighter fold, but this is unnecessary and results in dented metal. On the final fold, it aligned up perfectly with the start - all done by hand. Next the end tanks were cut out and folded up. This time I had to use a hammer, but these folds are internal and therefore not seen.

Here you can see the resulting box prior to welding

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Then tacking and final TIG welding - welds not up to professional standards, but overall i'm pleased with it - how many professional welders are also IT consultants "as a hobby" ?. I really should get round to buying the proper 5% magnesium rods, as i've only got 5% silicon rods. You may be interested to know that the welder used 33Kw of electricity - which at today's rates equates to about £6.00 worth of electricity.

7/1/07 - filter and deck plate

Ive added a 4 inch deck plate to the tank - this allows access to the water filter and also i can play around with adding Ice to the water tank in the summer - to see how much it lowers my inlet charge.

After spending several weeks looking for the tool holder, i finally had a go at screw cutting on the lathe - made loads of test cuts, which all kept tearing the ally up - in the end I done the one in the top of the photo by making multiple passes and turning the chuck by hand.

8/5/07: New Bosch cooler pump, tank fitted and bigger pipes

Fitted the tank and changed all my hoses for 19mm ID - which involved cutting, making and re welding the fittings on the cooler and both rads - Another lesson learnt is to fit 19mm (3/4") water fittings in the first place.

And I have FINALLY made a decision on which waterpump to use. My original plan was to purchase the Jabsco Cyclone pump which I knew was over the top, but I wanted to research the effect of varying the speed of the flow (using a motor speed controller) - but in the end I decided to use the Bosch PCA12 pump instead. Which was cheaper and also Automotive spec (although not waterproof ironically).Here's a comparison against my existing Bosch pump - it dwarfs it! - the pump is magnetically driven and pumps around 20LPM. To put that into context, my garden hose at full shifts 25LPM - so its not hanging around. Its almost totally silent also which is good.

Couple of shots of it installed - you have to make your own mounting bracket. I've since tidied the plumbing and made a splash-proof rubber cover for it.

Here's a short clip of it running to give you an idea of the flow rate. Its normally silent - but I left the hose off so you can see the flow. Datalogging shows it performs the same as when I ran the noisy vane pump with the big beer barrel during testing- so main gain is the silence!. I've tested the back pressure and its now down to about 3.5PSI (It was 5.5psi with the vane pump and small hoses). Overall it seems like a decent pump, I would recommend it.