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Surge tank and swirl pot

Started by _Keithy's_UC_ , Aug 16 2006 02:01 AM

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8 replies to this topic

#1 _Keithy's_UC_

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Posted 16 August 2006 - 02:01 AM

As the topic says, im keen to know the difference between the two. At the moment to the best of my understanding a surge tank has a low pressure fuel pump running to it from the tank, keeps full of fuel with overflow controlled with an overflow going back to the tank. Then from the surge tank the high pressure pump then feeds fuel to the motor. Aim of it is to prevent fuel surge (hence the name).

Swirl pots have me buggered... Always hear blokes referring to them as the same deal as a surge tank... Whats the go!!

Cheers
Keith

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#2 _82911_

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Posted 16 August 2006 - 07:59 AM

Technically speaking.... a "swirl pot" is designed to go in the cooling system on the outlet hose from the engine. The idea is that as the coolant "swirls' around in the pot it de-aerates and will then be able to be better cooled by the radiator. They work well if you have an engine that likes to make steam pockets...
They were factory fitment to Camiras.
A surge tank is as you described... for fuel, sometimes also called a "make-up" tank.

Cheers Greg..

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#3 _Herne_

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Posted 16 August 2006 - 09:23 AM

Thanks for the explanation 82911 as I too was wondering.

Cheers
Herne

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#4 _MAWLER_

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Posted 16 August 2006 - 03:03 PM

O.k, just throwing this out there. My mind is telling me that some ppl even have a little tank in the engine bay, but thats all the details I can remember. Am I on the right track?

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#5 _Herne_

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Posted 16 August 2006 - 03:24 PM

I used to use a small fuel tank in my race car engine bay, regulated with a needle and seat and fed from the main tank.

I think it was called a fuel block (could be wrong was a long time ago) basically it allowed a constant flow of fuel to my four Amal Monoblocks that I ran on a Bellett 1500cc engine.

Cheers
Herne

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#6 Dr Terry

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Posted 16 August 2006 - 04:28 PM

Hi Guys.

A 'swirl pot' in EFI lingo is a surge tank mounted inside the fuel tank. The return line is aimed so that as the fuel comes out it 'swirls' around in the bottom of the surge tank.

Dr Terry

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#7 Dangerous

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Posted 16 August 2006 - 05:50 PM

Keith, I think you're pretty much right on the surge tank, but clarifying that 'fuel surge' is referring to fuel starvation rather than variations in fuel delivery pressure.

As I understand it;

a surge tank is a smaller reserve fuel tank that is supposed to be always full or very nearly full, irrespective of engine fuel usage and G forces pushing the fuel around. It is usually tall and skinny, so that the bottom of it (where the fuel is extracted to be pumped to the engine) is guaranteed to be all fuel, and no bubbles or aerated fuel, even if you're halfway around a high G corner with not much fuel left in the main tank. It's hooked up as you explained it.

A swirl pot is a partially enclosed area inside the main fuel tank where the fuel pump pickup sits (or the whole fuel pump, if it's an electric in tank fuel pump), and the return fuel line feeds straight into the swirl pot area. It's another way of minimising fuel aeration or starvation by having a partially enclosed (can't be fully enclosed, as it needs to allow fuel in the main tank to easily flow into it) and baffled area that the fuel pickup can always pick up fuel from inside the main tank, and the added benefit that it is always topped up by the fuel return line.

Swirl pots of some kind are pretty much always used on production cars these days, and surge tanks are needed for higher performance (read higher G force, and higher fuel requirement) cars.

AS I said - as I understand it.