Swirl Pots

After some advice on fuel system.

Going for a ITB fuel injection system and want to consider a swirl pot as the car is likley to see some track use also.

Layout will be, out of the two tanks using seperate low pressure pumps and filters into a swirl pot.
From there to high pressure pump and fuel rail.
Bleed back to the top of the swirl pot and vent back to the tank.

So, the question is, do i need a twin inlet swirl pot
If the answer is yes, where can i find one, beause i am not seeing any ?


Ian Anderson

Lifetime Supporter

You will need a cross over valve like a Pollack valve or a system of solenoid valves and non return valves

Now the Pollack valve is not too bad but can fail and you can get fuel drawn from one tank and fed back to the other

Solenoid valve are good bit can be restrictive for some applications and require constant power to keep it open

Honestly if I were doing it again I would connect ther two tanks and feed that connection to a LP pump to swirl and from there to the rail

I would also look at a swirl pot with a submersible or in tank pum enclosed therein so it is one less piece to locate in the cramped engine bay

So in answer to your question you do not need a double feed swirl as you will need other parts in the system to stop fuel crossing between the tanks


Terry Oxandale

Skinny Man
I'm using a pot that has four inlet/outlet holes. I've joined the two LP pump outlets (with in-line one-way valves, together into a single line (from a Tee) that then enters the pot in one of the four holes. It works fine, but I have an on-off-on switch that allows me to use only a single LP pump at a time (swap between the left or right tank pump), with the pot re-circulation going back to the tank of choice through a manual valve. This way I basically operate off of a single tank, and then simply swap pumps to transfer from the unused full tank into the nearly empty tank.

I did not use a single pump drawing from both tanks due to the desire for two separate systems that could operate independently, as well as the fear of drawing air from one tank even if fuel was in the other (if drawn from the Tee).
Last edited:
You may be noticing from the last post that electronics can be a blessing and a curse at the same time. The one suggestion that I like from Ian is the crossover system. It is what I have in my 40.It simply is a 1/2" line from the middle of the bottom of one tank to the other. The theory is that as fuel is consumed from the main tank(passenger side in my case), It is replenished by the other tank. Some incorporate a one way valve. I currently have a 3/8" line at present but plan to change over at the end of next driving season. With this type of set up you need to take a few other things into consideration. On the swirl pot, the return to the tank line needs to be the top most outlet (Overflow). Otherwise you may develop an air bubble in the swirl pot. Getting air to the high pressure pump will spell an early death to the pump(more on this line in a minute).
You also need to think about your tanks and their setup as well. The tanks need to be baffled or filled with foam to keep sloshing to a minimum. Along with the sloshing theme, you might consider putting in a reservoir in the back of the tank to draw fuel from. the low pressure pumps can take a little sucking of air fairly well. With a reservoir you decrease it. I have a flapper valve that helps hold fuel in the area(fuel in but not out).The arrangement of your fuel lines will help in this regard as well.In the reservoir you should have of course your pickup line for the low pressure pump(unless you go for the in tank pump). You should also have the return from the swirl pot(overflow) in this area as well. Keeping your fuel pickup covered in fuel is a good thing. The only bad thing for this area is the fuel level gauge. You don't want it there. It will give you false readings and make you think the tank is full or near full most of the time. When you finally run out of gas(will happen rather quickly with that set up) it may leave you stranded. So put that just outside of that area. Speaking of senders, with foam and baffles, you may be hard pressed to find an area(read space) that you can put the sender. I use a Centroid sender. It has no moving parts and it has the beauty of having a line that can be used to wire to a warning lite or alarm for low fuel. Google centroid fuel sender for detailed information(several sites).
These tanks being long and narrow can lead to air pressure problems within the tank. With the fuel filler in the front and parking down hill, the air bubble in the rear will build up pressure from the sun , or heat from any source in or around the car, which will force fuel up the filler neck and out the filler. You will need vents from the front and the rear of the tanks which should go to a rollover valve that will allow the to and fro movement of air into and out of the tanks, but will stop the flow of gas if a roll over occurs. Demon Tweeks has a good selection. Fuel Tank Vent Valves | Fuel System | Motorsport | Home | Demon Tweeks
Swirl pots and reservoirs also.Fuel Swirl Pots & Collectors | Fuel System | Motorsport | Home | Demon Tweeks
Some add charcoal canisters to these lines to keep the smell of gasoline out of the garage after a spirited drive.
As you can see, there is a lot more out there than just a quick answer. Hopes this gives you some ideas.

Thanks guys some good ideas, and as always a mixture of solutions.

Ian, the valve looks interesting, going to look closer at that. Thanks.

Blueovalz, i was thinking of going that way myself with non return valves, but i can see the advantage of the valve above being able to divert the excess fuel back to the tank in use. Only disadvantage i can see is that you would drain only one tank at a time... how would one full tank and one empty tank effect the balance ?

Bill, Like that fuel level sender, not sure if it works with a standard gauge, will need to investigate more.

Tanks are already built and fitted, so stuck with what i have... however, they are fitted with baffles and a reservoirwith a trapdoor. Fuel pickup and return are located there and the sender unit is in the main area of the tank. Think that is what you are proposing ?

A lot of reading to be done first.
Thanks agian.
When ordering you need to know two things. You need to know your depth of the tank and the Ohm rating of your gauge at full and empty. 0-90, 10-180 etc. Consult your gauge manufacturer. May be in the literature that came with the gauge.

Yes, very nice looking units Ian, but not cheap.
Being this side of the pond maens another 25% on top of that price for me and shipping.


Ian Anderson

Lifetime Supporter
Sure but it gives the idea

A UK manufactured item fitted with say a Range Rover fuel pump would not cost that much


Terry Oxandale

Skinny Man
... how would one full tank and one empty tank effect the balance ?
For me it was an offset of driver weight. In a longer event, I'd start with both tanks full, and empty the driver's tank first, then swap to the passenger side tank (which would start to refill the driver's side). With two gauges on the dash, side by side, I get a good view of their levels and which LP pump to run.

For the shorter events or runs, I'd close/open the manual valves and run solely off the full passenger side tank only, and leave the driver side near empty. There are advantages to all the above suggestions. It just depends on personal use. The crossover would most likely equalize the tanks at an average level, which then gets drawn down equally, but my car is not balanced in weight (side to side), even with the dry sump tank, battery, etc, on the passenger side. So the tank choice is nice for those tracks that sometimes change from CCW to CW direction. It allows me to load the "inside" of the car depending on the turns and configuration.

Randy V

Lifetime Supporter
Terry, you may change your mind once you drive the car that way... I've set up a bunch of race cars over the years and I would hate to try and set up a car that has a sideways moving weight bias..
Unless... You set it up for the track direction and use only one tank.. And even then, it may be learning how to drive two different cars..
I went for the pollak valve which works well , I did however ruin one because swarf from the tank got into it. I would highly recommend a decent prefilter set up irrespective of the system you use. I would also recommend a decent size swirl pot because with these tanks less than brimmed fuel can be away from the pickup for a long time under acceleration/braking, add that to the time it takes for the air locked LP pump to grab fuel again.

I like your suggestion for the pre filter. Good advice. I had a high pressure pump quit due to line tubing sluff when I changed the tubing to the hi pump due to leaking from dry rot.
The conditions you mentioned are the very reason I set my fuel system up the way it is. With fuel in the circuit from swirl pot to high pressure pump to injectors and back to swirl pot,,, that has to be at least 1 gallon+ that the injectors will have access to. The return to the tank(one set of pumps) is plumed to my reservoir area in the rear, so the pickup has access to all that fuel in a low tank setting. My low pressure pump should not be starved for a long period of time(my opinion). It will have periods of air for sure, but with left and right turns and acceleration points I think it will see more fuel and fewer times without(at least I hope so). We can't stop it(air starvation) entirely. I just try to minimize it.


Ian Anderson

Lifetime Supporter
Longest "air suck" period I had in my car was on low tank and a long downhill

All I can say is at that stage I was very happy I did not have tanks linked and I switched over and the other tank was still full enough for for the pump to suck fuel

I run Facet Red top as my LP pump and it goes from click click with fuel going through to bang bang when sucking air it really hammers away?

I run about 2 litre swirl and have killed one Bosch 044 by it managing to suck air so this is a real problem!

I'd been looking at the same solution(s) to the same issue. Decided to go with a single Aeromotive Phantom EFI in-tank fuel system on the right side fuel cell. This pump feeds the EFI from that cell only, and is fitted completely into the cell. The left fuel cell is fitted with a single Holley low pressure pump that is mounted externally of the cell and simply transfers fuel from the left to the right as necessary (manually mounted dash switch). If you thought it necessary, the low pressure pump can be relay switched to flow either direction (reverse polarity/push-pull), to transfer fuel in either direction. I had planned for Pollack valves, multiple fuel pumps, filters, swirl pots, etc. this just seemed most simple and effective to me. My GT is an RCR model. The fuel cells have a huge area available in rear most portion of the cells; a flapper valve is installed to allow that area to effectively act as a "swirl pot".

Randy V

Lifetime Supporter
Flapper valve Doug? What number chassis did you buy? I don't recall there being any on my car (45)...
I like your solution with the low pressure pump to main tank. My question is, as I thought about this solution many years ago, how do you control the pump for shut off(automatic) if the main tank becomes full?? I would think that if the main tank shows low(going downhill or stoping for instance) the auxiliary tank would be the same(sooner or later) and that pump would suck air also. Or do you have a reservoir on that side as well.
I could see using two Centroid sender low level light alarms(one in each tank) as a way to trip the reserve pump only, on and off automatically. Here is one way to wire it.
!st Relay
Main power in to 1st relay(30 pin)
87A pin not used
Main power out(pin 87) to the 30 pin of the second relay
Low warning light in main tank to the 85 pin
86 pin to ground.
2nd relay
Main power from 87 pin above to 30 pin
87 Pin not used
87A pin to Aux. pump
Pump would run when low level light from main tank is on.
Low warning light in Aux. tank to 85 pin
86 pin to ground
When the Aux tank warning light is on the pump is off and will not run even if it receives a signal from the main pump.

OR you might be able to use a latching relay. Not sure how it would work with both signals on???

How about a bespoke swirl pot with two LP inlets, one HP outlet, one HP return, and two tank returns with solenoid valves in series with LP pumps.

Switching one either pump will open the outlet back to its own tank.
Or put both on and vent back to both tanks if the flow will split evenly.


Correct to say the fuel cell mod was not from the factory. The flapper is an easy install; 1" diameter hole in bottom of fuel cell baffle, hinged aluminum flap allows fuel into rear most compartment but restricts (does not stop) fuel migration forward.

My original installation was to have two LP pumps feeding off the left side tank to/from the right side and supplying a swirl pot and then having a HP pump being supplied from the pot and returning to the pot (and then overflowing/returning to the fuel cell).

The Aeromotive Phantom kits have made it all too easy for me. And, for the price from Jeg's (don't go by retail pricing on Aeromotive website), it's as cheap as all the AN fittings I had planned to make it all work.

As for fuel transfer; I will fill both tanks, run the right side (HP EFI) tank to under 1/2, fill til full from the left side, then do it again til I suck air. I know it's not elegant or complicated, but that's about all I could wrap my brain around!

1 LP Holley pump, suck from the left and deliver to the right.
1 Aeromotive Phantom EFI 340 Throttle Body Kit (HP pump, fuel regulator, 10 micron filter, fittings, lines, etc.), deliver from the right to 8 Stack and return to the right.

Besides venting there is not much else to it. If anyone sees anything I'm missing please let me know!
Last edited: