Fuel Swirl-pot location
Discussion
OK, a question for you experts out there!
Seems that many swirl-pots are made with a base plate, and I have seen many builders place the s-pot low down between the engine and frame. Others have placed the pot in the L-Hand side-pod above the tank...
...and so to the question. Which is the optimum position relative to the engine for the swirl-pot to swirl and do its job properly? ..or does it not matter?
cheers
keith
Seems that many swirl-pots are made with a base plate, and I have seen many builders place the s-pot low down between the engine and frame. Others have placed the pot in the L-Hand side-pod above the tank...
...and so to the question. Which is the optimum position relative to the engine for the swirl-pot to swirl and do its job properly? ..or does it not matter?
cheers
keith
The term 'swirl pot' is more related to dry sump oil systems where you want the air which has been drawn by the scavenge pumps to be released from the oil before it is re-used. Making the liquid 'swirl' round a cylinder helps separate it.
In a fuel system the pot is just to provide a head of fuel above your high pressure pump (which is very poor at sucking) and to provide protection against fuel surge during cornering.
There is something very wrong with your fuel system if air is returning to the pot so the pot can be any shape you choose and needs to be mounted somewhere above the HP pump.
Steve
In a fuel system the pot is just to provide a head of fuel above your high pressure pump (which is very poor at sucking) and to provide protection against fuel surge during cornering.
There is something very wrong with your fuel system if air is returning to the pot so the pot can be any shape you choose and needs to be mounted somewhere above the HP pump.
Steve
Edited by Steve_D on Wednesday 5th May 07:28
and my feelings
as all Ultima owners do (except Robin) as soon as i completed my return journey from Stoneleigh i opened the rear clip to look for leaks etc and felt the temperature of the swirl pot( side pod over the tank), it was relatively cool and indeed a lot cooler than the fuel rails!! I think as Dave has said keeping the fuel as cool as possible can only be a good thing, so keep it as far away as you can from any heat sources.
as all Ultima owners do (except Robin) as soon as i completed my return journey from Stoneleigh i opened the rear clip to look for leaks etc and felt the temperature of the swirl pot( side pod over the tank), it was relatively cool and indeed a lot cooler than the fuel rails!! I think as Dave has said keeping the fuel as cool as possible can only be a good thing, so keep it as far away as you can from any heat sources.
Steve_D said:
The term 'swirl pot' is more related to dry sump oil systems where you want the air which has been drawn by the scavenge pumps to be released from the oil before it is re-used. Making the liquid 'swirl' round a cylinder helps separate it.
In a fuel system the pot is just to provide a head of fuel above your high pressure pump (which is very poor at sucking) and to provide protection against fuel surge during cornering.
There is something very wrong with your fuel system if air is returning to the pot so the pot can be any shape you choose and needs to be mounted somewhere above the HP pump.
Steve
Sorry Steve but I disagree ..... (feel like I just told God he's wrong)In a fuel system the pot is just to provide a head of fuel above your high pressure pump (which is very poor at sucking) and to provide protection against fuel surge during cornering.
There is something very wrong with your fuel system if air is returning to the pot so the pot can be any shape you choose and needs to be mounted somewhere above the HP pump.
Steve
Edited by Steve_D on Wednesday 5th May 07:28
An ultima with fuel pickups in the tanks on the side's, may at low fuel levels ( and some spirited driving )suck air from the tanks, that air has to be removed before entering the high pressure pump other-wise your engine might get leaned out under full throttle out of the bend. The Swirl Pot is just as important on the fuel side for De-aeration as the Dry sump tank. Yes under normal driving and plenty of fuel in the tanks your never going to get air into the Swirl pot, but these cars are meant to be driven hard and to stop driving because you tanks low seems a waste...
PS Sorry God
GTRCLIVE said:
PS a correctly designed fuel tank generally has the fuel pickups nearer the back of the tank, as it's easy to cost down a hill but hard to drive up it with the pickups nearer the front.... Never drive up Porlock Hill with less than half tanks in a std ult...
If you drive down Porlock hill with full tanks, they will be pi$$ing petrol out of the caps.
!
GTRCLIVE said:
Slapped me down
Yes you are of course right.I was thinking of the fuel returning from the fuel rails which has no reason to be aerated and forgot all about the fuel coming from the tanks.
I do still believe the shape of the tank is not critical as fuel is so much thinner than oil so the air can easily rise to the top of the tank without the need for any 'swirl' action.
Cool is good too.
Steve
rdodger said:
Is there any reason why the Ultima tanks couldn't have internal swirl pots? It would cut down greatly on the plumbing.
.......or maybe a small, shallow sump where the in-tank pump's would locate.Its something I'm scratching around with at the minute, using a pair of Bosch pumps fitted with socks and also a sender that drops in from the top, as one complete unit.
Am hoping it will give a neat, quiet and trouble free fuel system. Just need to find the right pump controller as full fuel supply isnt needed all the time, otherwise a return like a soil pipe will be required !!
I don't get the whole fuel S-pot (FSP) concept. Isn't there a difference between FI and carb setups?
1. IF the FSP doesn't have an air relief vent, would it not eventually almost completely fill with air (if the pumps are pushing air) causing a rather large belch into the fuel rail?
2. If the FSP has an air vent, would it not also have a relief cap (like the small coolant return line) with an adjustable spring that's set just greater than the pressure of the regulator?
3. If the FPS has an air vent, would it not also have to be the highest point on the system?
Does anyone run an FI Ultima without one? I just can't get my head around how the FSP works for FI engines.
1. IF the FSP doesn't have an air relief vent, would it not eventually almost completely fill with air (if the pumps are pushing air) causing a rather large belch into the fuel rail?
2. If the FSP has an air vent, would it not also have a relief cap (like the small coolant return line) with an adjustable spring that's set just greater than the pressure of the regulator?
3. If the FPS has an air vent, would it not also have to be the highest point on the system?
Does anyone run an FI Ultima without one? I just can't get my head around how the FSP works for FI engines.
Builder said:
I don't get the whole fuel S-pot (FSP) concept.
Hey Scott good to see you around... how's the build coming along?Think of the fuel system as two independent sides, low pressure (LP) and high pressure (HP). The LP pumps feed from the fuel tanks to the swirl tank (often referred to as a vapor separator tank (VST)) as it helps eliminate vapor lock. The VST has an outlet back to the fuel tanks incorporating a back pressure valve to control VST pressure (say 10 psi). The LP side is designed to supply more fuel than the HP side requires under WOT conditions. Thus there is a constant flow of fuel back to the fuel tanks (controlled by a 3 way valve if you have dual tanks so you don't pump from one tank across to the other). The HP pump draws fuel from the VST for the fuel rails and the HP regulator bypasses back to the VST.
BTW I don't run a VST with FI on the CanAm, but I do have to keep the tanks at least 1/4 full on spirited track days.
rdodger said:
Is there any reason why the Ultima tanks couldn't have internal swirl pots? It would cut down greatly on the plumbing.
There are in tank FI pumps available that have the pressure regulator incorporated and simply bypass right inside the tank. It sure makes for a simpler fuel plumbing system. Again the pick up needs to see fuel all the time and the best way to stop fuel slosh is internal baffles and/or a foam fill/insert in the tanks.Julian
Edited by JoulesCanAm on Thursday 6th May 07:01
A Holley has 2 fuel bowls that can take out a small amount of air if the fuel pumps pickups aren't covered in fuel. But a FI engine if the High Pressure pump gets any air the engine will run lean for a split second or so. So the idea is to have a small Tank or FSP that is guaranteed not to have any air in it. So the Low pressure pump (Or Pumps) can supply the FSP with a over flow return at the top of the FSP back to the Main Fuel Tanks, any air or excess fuel gets returned then to the Tanks.
The idea being that the High Pressure pump (Or Pumps) take there fuel from the FSP and should never have any air in them, also the pumps can be mounted under the FSP so there should also never be any problems with suction or priming etc....
Hope that makes sense.....
Ps allot of Main High Performance cars have a different type of baffled pickup area inside the tank that a In tank pump sits in, to get round having a external FSP.... but that's another story...
The idea being that the High Pressure pump (Or Pumps) take there fuel from the FSP and should never have any air in them, also the pumps can be mounted under the FSP so there should also never be any problems with suction or priming etc....
Hope that makes sense.....
Ps allot of Main High Performance cars have a different type of baffled pickup area inside the tank that a In tank pump sits in, to get round having a external FSP.... but that's another story...
V8 Vum said:
...and so to the question. Which is the optimum position relative to the engine for the swirl-pot to swirl and do its job properly? ..or does it not matter?
cheers
keith
I don't know what the best location is, but mine is located as you can see in the picture - I have had no problems with it.cheers
keith
Regards.
JoulesCanAm said:
Hey Scott good to see you around... how's the build coming along?
Great! All too slowly, but getting there. Thanks for asking.Okay, that works. I didn't think about a return line (lines) to the tanks, because that's where my returns go already. There's one line out of the regulator to the rail, the other split back to the tanks. So, with a VST and fuel injection, you could have two return lines to each tank along with, possibly, some check valves if you merge them.
GTRCLIVE said:
Hope that makes sense...
Yes, sir. So, all said, I think that clears up the position for the VST:A - VST does not have to be at the highest point, because it's part of a closed pressurized system where the return is to the tank(s).
B - The VST should be upright (the return line at/near the top), so any trapped air is free to belch back to the main tank(s).
Thanks, guys. My system doesn't include a VST as designed. If starvation is an issue, I will consider adding.
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