iwbunting
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| posted on 29/7/04 at 07:41 PM |
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Swirl pot
Has anybody got a drawing or description of a fuel tank with inbuilt swirl pot suitable for EFI.
One that actually works would be nice.
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Mark Allanson
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| posted on 29/7/04 at 08:23 PM |
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Better than a drawing or description of a swirl pot...
 
Rescued attachment Swirl pot.jpg
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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niceperson709
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| posted on 29/7/04 at 10:32 PM |
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For my Fuel injected Nissan I'm going to reuse the plastic swirl pot out of the original donor tank ,only thing is that i have to make sure that
I dont fry it while welding the tank up as it can't be fitted in side otherwise  ]
best wishes
Iain
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Mark Allanson
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| posted on 29/7/04 at 10:56 PM |
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How are you going to fasten the pot to the inside of the tank?
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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dave1888
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| posted on 29/7/04 at 11:20 PM |
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Have you given any thought to an external swirl pot burton power do them for £70
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jack trolley
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| posted on 30/7/04 at 12:56 AM |
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I've read that the VW Golf EFI pump has a integral swirl pot.
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zetec
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| posted on 30/7/04 at 03:16 AM |
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Only added problem with external swirl pot is the need to have a low presure pump to feed it.
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stephen_gusterson
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| posted on 30/7/04 at 09:01 AM |
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I have always been a bit confused over 'swirl pot theory' as to me, a lot of people's ideas on what constitutes a swirl pot is too
complex, or doesnt work.
I cant see how an internal swirl pot would work......
I see the mechanism as follows. Low fuel in tank is sloshing around. You need a way to trap it. So, you have a small container in the tank, fixed to
the lower surface of the inside of the tank, like marks pikkie. So, you need holes in the wall of the swirl pot to allow fuel to fill it. These will
be the same holes that will allow it to drain right back out again....plus you have the efi pump emptying it, so
fuel in = thro the side holes.
fuel out = thro side holes AND from the pump.
This looks to me like a losing struggle.
If you route the efi return back into the swirl pot, that takes one thing out of the equation, but you still have an equal ability for fuel to exit
the side wall holes at the same speed it went in!
why do you need a pump for filling a swirl pot? Just put it lower than the tank and gravity feed it thro a large dia pipe.
My theory was that fuel needs to be supplied to the engine when the tank level is 'sloshing'. Ideally, you need to maintain a reserve of
fuel such that for an average slosh, the fuel will hold up until the next slosh, at whatever the flow rate is. Scientifially, I had no clue of what
these factors were, so I used the American technique - IE make it as big as you can. In my case its not a huge swirl pot, just a 180mm length of 50mm
dia tube, IIRC its about 1/4 - 1/3 litre - cant be bothered to work it out.
This tube is welded to an exit hole on the tank bottom - the hole is approx 20mm - to easily let fuel in. 'slosh' wont allow the fuel back
out as easily as a surface mounted pot, as gravity and the 'walls' at the 25mm entryb hole will tned to turn the fuel back down into the
pot.
so, as long as the average slosh keeps fuel in the tube, it says there, so that only the pump draws it out. so....
fuel in = thro the 20mm top hole.
fuel out = from the pump, and sloshing back out of the top of the 20mm hole (small due to gravity).
The only mod I would make to my scheme would be to allow the efi return to dump right back into the 20mm hole of the swirl pot. It doesnt - it just
dumps in the region of the swirl pot via a tube to the base of the tank.
atb
steve
 
Rescued attachment swirl.jpg
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j_davis
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| posted on 30/7/04 at 09:32 AM |
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The swirl pot in my tank takes the form of a cylinder thats been split longintudinally and the edges overlapped for 45deg, the gap between the edges
is 15mm. This is sealed to the bottom of the tank inside.
The fuel pump sits inside the pot and the return line is fitted inside the overlap, so as to direct the return flow into the pot.
In this way the return flow creates a swirl in the pot and also acts as a non-return valve for the inlet to the pot (which is through gap where the
overlapped section is), as the flow encourages fuel to enter the pot and stops it leaving.
I tested it with water using a washer pump to give the flow and it easily kept the pot full whilst there was practically nothing in the rest of the
tank.
James.
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stephen_gusterson
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| posted on 30/7/04 at 09:44 AM |
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is the term 'swirl pot' just a bit of miss-naming?
why do you need a 'swirl' as such?
atb
steve
link to fuel pumps with integral swirl
http://www.vdo.com/siemens/en/prod_fuel_pumps.asp
[Edited on 30/7/04 by stephen_gusterson]
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crbrlfrost
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| posted on 30/7/04 at 09:44 PM |
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The main problem, and I may be nit picking, with the second pic is having to set the fuel tank up high. Eight pounds a gallon starts to add up the
higher it sits. I would problably try experimenting with a small sump and trap profiles to reduce sloshing, along with feeding the return line
directly back into it ala the pic. Cheers!
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Peteff
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| posted on 30/7/04 at 10:12 PM |
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Is this fuel swirling round the inside of the tank or is it sloshing round the inside of the tank or does it only swirl once it gets into the pot?
I'm getting confused by the different terminology. It's a device to prevent the pump from running dry isn't it?. Set the fuel gauge
to empty when it's on quarter and don't let it get lower than quarter so you always have half a tankful. Simple.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Mark Allanson
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| posted on 30/7/04 at 10:23 PM |
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Steve, I agree with what you say, but my pot is welded to the baffle and the only route between the two sides of the tank is through the pot, so
whichever side the petrol sloshes it has to pass through the pot, so I should have a constant supply
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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zetec
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| posted on 31/7/04 at 06:56 AM |
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I suspect it is called a swirl pot because it's other function is to remove bubbles in the fuel feed to the injection pump that would then end
up in high presure fuel feed to the injectors. Just like a tap running at high presure into a bucket you would get too many bubbles produced with the
return pipe directed at the swirl pot inlet.
Found this out when I could hear air running through my pump with the car at rest and with half a tank of fuel.
[Edited on 31/7/04 by zetec]
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Cita
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| posted on 31/7/04 at 09:18 AM |
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Why not make two narrow vertical tanks each side of the boot connected with a T at the bottom?
The chance that both will rapture in a tailender is small.
Should cive you more bootspace too.
Just an idea
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