Swirl Pot

[XKRacer]

OK I am gonna play as thick as possible, all I want in simple terms is......can somebody explain to me how a fuel swirl pot works and what are all the pipe connections are for?


I have done a few searches but not found anything that makes me happy

Thanks

[dtype38]

In its simplest form a swirl pot will have three connections: a feed about half way up, a take off at the bottom and a vent at the top. The purpose is simply to separate out any entrained bubbles in the liquid feed, venting the gas out at the top and taking neat liquid out at the bottom. The pot is usually round with the feed at a tangent to the side so that the liquid spins in the pot (hence "swirl") which promotes better separation of bubbles from the liquid. When used in a fuel system they help prevent air getting into the engine feed if surge in the petrol tank causes the lift pump intake to be uncovered. Using one ususally means needing two pumps, one to feed the pot and one from the pot to the engine.

[Notso Swift]

Add an over flow return to the main tank as well, or some from of switching device to the lift pump (like a float level)

[XKRacer]

OK I have been looking on Ebay and various fabrication sites. Most seem to have 4 connections 1 at the top a breather an in and out and an overflow?

Is this correct........And how big a swirl pot would I need for a 4/5ltr V8?

[AlexH]

The swirl pot is to provide a surge and air free fuel supply to the carbs or injector pump.

There will be 4 connections, and starting from the bottom up they will be; 13 mm feed to injector pump central feed.

8 mm return from the fuel rail return tangential feed.

8 mm feed from the main tank via a hi flow low pressure pump.

6 or 8 mm from top centre of swirl pot to return the air/excess fuel back to the main tank.

The capacity will be about 1.5 - 2 Litre, 200 mm H x 100 mm Dia should be OK.

With carbs, the bottom outlet can be 8 -10 mm Dia, and may not need the fuel rail return depending on the system

[XKRacer]

Thanks all for your input.

I have been talking wih a guy I know and he says because of the injection type fuel pump I have I shouldn't have to worry about a swirl pot

The car is a Jaguar XK wih a high pressure system?

[Notso Swift]

Actually it is important so that you can use the full capacity of your tank without fuel starvation.
What you can do is a tank in tank set up, where you have a "swirl pot" around the main (pressure) pump with a low pressure feeding into the is area, any over flow just runs out of the top (the bottom is sealed, to the floor of the tank, the top isn't) the return can also come into the "inner tank" or not, not that imortant... better if it does for supply purposes but sometimes hard in a production car.
This can quite easily save you carrying an extra 15kg of fuel which is dead weight and is easy to do, after all parts are production and all you are adding is one low pressure pump, and a ring. Most tanks have a nice hole in the top for easy access as well.

[dtype38]

In actual fact I used to run a swirl pot system on my own car, but found that it so good at running my fuel tank completely dry that twice the lift pump from the tank siezed because it was spending so much time trying to pump air! It was so annoying that I went back to a single pump system but with a well designed tank that can run down to less than 5ltrs without uncovering the pump pickup.

[XKRacer]

I am trying to find out how my tank is constructed before I commit, I am not holding my breath for anything too fancy, at the end of the day it started life as a GT car rather than a sports.

So we shall see

[R59]

I had one made for my Nova GSi. Mine has a main tank in & return - fed by a Facet Red Top, then has the Injection pump outlet and return. The main tank return is in the top of the pot, the injection pump feed is just off the bottom. The main tank input, and injection return are 90degrees apart about 1" down from the top. the capacity of my pot is about 2 - 3 pints.

Works a treat!

For a larger engine, I'd probably still say that it's big enough, though I'd probably be tempted to run a second pump, and with larger capacity to feed the pot.

[XKRacer]

I have found out my tank does have a kind of in-built swirl pot .....just not sure how effective it will be?......We shall see

Just another note I have had a couple of people tell me the fuel regulator should be on the return and not the feed......can anybody clear that up?

Cheers

[phoenix]

Originally Posted by XKRacer

I have found out my tank does have a kind of in-built swirl pot .....just not sure how effective it will be?......We shall see

Just another note I have had a couple of people tell me the fuel regulator should be on the return and not the feed......can anybody clear that up?

Cheers

All fuel pressure regulators I have come across on fuel injected engines are bypass regulators. They control the pressure on the inlet side by bypassing excess pressure through the oulet.

If that is the type you are using then the regulator should go on the end of the fuel rail. The fuel bypassed by the regulator will be at a lower (unregulated) pressure and should be returned to the swirl pot, or the fuel tank at least.

[XKRacer]

Well that makes sense so I will stick with what I have done.....cheers