Fuel swirl pot location
Discussion
I need to relocate the high pressure fuel pump and the swirl pot which supplies it. How much higher than the fuel tank should I locate it? Main concern is that the swirl pot return outlet should be higher than the return port into the tank, is around 50mm OK or should I aim for more?
100SRV said:
I need to relocate the high pressure fuel pump and the swirl pot which supplies it. How much higher than the fuel tank should I locate it? Main concern is that the swirl pot return outlet should be higher than the return port into the tank, is around 50mm OK or should I aim for more?
If I assume you have a LP pump supplying the pot then the swirl can be anywhere you like.Ideal would be the LP pump close to, and as low as possible, relative to the tank or in tank.
The swirl can be anywhere you like but you want the largest possible outlet pipe with the shortest possible pipe to the HP pump inlet to reduce the chance of cavitation at the pump inlet.
If this is not possible then put a restriction in the return line from swirl to tank. This will create a positive pressure (about 6psi) in the swirl pot which will help overcome the pressure drop at the inlet of the HP pump. the only reason for the return to tank is to remove any air/vapour from the HP system so the restriction can be very small.
Steve
Hi Steve,
thank you for concise reply.
There is an LP pump located below the bottom of the tank feeding the swirl pot.
Outlet of swirl pot is 12mm (IIRC) feeding a Bosch 44 type HP pump.
Reason for relocation is heat soak causing restart problems - presently the pot and pump are under bonnet so absorb heat from radiator exhaust and LH manifold. Plan is to relocate to rear adjacent tank and away from heat sources.
many thanks!
100SRV
thank you for concise reply.
There is an LP pump located below the bottom of the tank feeding the swirl pot.
Outlet of swirl pot is 12mm (IIRC) feeding a Bosch 44 type HP pump.
Reason for relocation is heat soak causing restart problems - presently the pot and pump are under bonnet so absorb heat from radiator exhaust and LH manifold. Plan is to relocate to rear adjacent tank and away from heat sources.
many thanks!
100SRV
Down the back will be fine. Just leaves the feed and return pipes which you can wrap in heat matt for the short distance before they clear the engine bay. Leave them uncovered after that as heat matt will keep the heat in at the point where you want to start cooling the fuel down.
As I said before keep the pipe from swirl to pump as short and straight as possible.
Steve
As I said before keep the pipe from swirl to pump as short and straight as possible.
Steve
OP, it's rarely good for pumps and swirl pots to be engine mounted :. if possible, always install at fuel tank end. Your install should be as follows, tank -to- filter#1 -to- LP pump -to- swirl pot -to- HP pump -to- HP filter -to- fuel rail. Fuel rail return to swirl pot. Top swirl pot outlet final return to fuel tank. Importantly, you need to check the specified static lift of the LP pump, this is the weak link in swirl pot installs. I use Facet Race Red Top units for this as they have a 60cm lift from bottom of the tank. Plus, the LP pump needs to match flow rate of the HP pump [this should already be matched to injectors combined peak flow rate and the rail return pressure regulator. If you're using the Bosch 044, is this going in to a V8? If so the above set up works flawlessly up to about 280bhp. Only other notes,
- if possible try to install in the boot of the car and between chassis rail areas for good accident safety...it's also good practice to fit a cover to ensure no boot items hit the fuel set up
- I prefer to have separate relays to LP and HP pumps as this aids any req'd fault finding
- don't fit fuses to your fuel pumps as they can blow at the worst possible time i.e. on track/under fast driving...which you would not want
Hi V8250,
thanks for the tips!
Fuel pump and swirl pot chassis mounted (within the rails in collision-safe locations) albeit in an unfavourable position. Vapourisation is a new problem resulting from a change to wiring allowing cooling fans to run with engine off thus soaking the fuel components with warm air (fan exhaust swirls in that direction).
Installation exactly as you describe, Facet solid state fast road is my LP pump and (mentioned in earlier post) mounted below bottom of fuel tank. The flow rates of the whole system were analysed and the LP pump can keep up with the HP pump's requirement.
Fabrication time now!
thanks for the tips!
Fuel pump and swirl pot chassis mounted (within the rails in collision-safe locations) albeit in an unfavourable position. Vapourisation is a new problem resulting from a change to wiring allowing cooling fans to run with engine off thus soaking the fuel components with warm air (fan exhaust swirls in that direction).
Installation exactly as you describe, Facet solid state fast road is my LP pump and (mentioned in earlier post) mounted below bottom of fuel tank. The flow rates of the whole system were analysed and the LP pump can keep up with the HP pump's requirement.
- Fuel pumps have seperate relays - LP via primary ignition relay and HP via 14CUX controlled relay.
- If fuses are blowing you have an electrical problem which requires resolution - this car has covered over 100,000 miles (30,000 on EFi) and the only time a fuse for the fuel pump has blown is when the fuel pump itself has failed.
- Are the fuses adequately rated?
- Are they located in an area with high ambient temperature?
Fabrication time now!
v8250 wrote "don't fit fuses to your fuel pumps as they can blow at the worst possible time i.e. on track/under fast driving...which you would not want
Over the years I have witnessed so many stupid things that have been said or done by so many people that should not be allowed to go near a car for any other reason than to drive it, the above comment could be found very funny if it wasnt so dangerous
Over the years I have witnessed so many stupid things that have been said or done by so many people that should not be allowed to go near a car for any other reason than to drive it, the above comment could be found very funny if it wasnt so dangerous
Penelope Stopit said:
v8250 wrote "don't fit fuses to your fuel pumps as they can blow at the worst possible time i.e. on track/under fast driving...which you would not want
Over the years I have witnessed so many stupid things that have been said or done by so many people that should not be allowed to go near a car for any other reason than to drive it, the above comment could be found very funny if it wasnt so dangerous
Bizarre for sure !!Over the years I have witnessed so many stupid things that have been said or done by so many people that should not be allowed to go near a car for any other reason than to drive it, the above comment could be found very funny if it wasnt so dangerous
It would be idiotic not to fuse such circuits.
Generally, for LV circuits, the fuse is to protect the wiring and not the consumer! IE, you rate the fuse well above the maximum current draw of the fuel pump, something like 1.5 or 2 x higher at least. The purpose of the fuse is to blow and prevent a loom fire in the event the loom is short circuited, which, in a car with it's chassis as one of the conductors is really very easy to do!.
Many years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
Many years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
Max_Torque said:
Generally, for LV circuits, the fuse is to protect the wiring and not the consumer! IE, you rate the fuse well above the maximum current draw of the fuel pump, something like 1.5 or 2 x higher at least. The purpose of the fuse is to blow and prevent a loom fire in the event the loom is short circuited, which, in a car with it's chassis as one of the conductors is really very easy to do!.
Many years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
You should have posted him a small fuse with his name on it lolMany years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
stevieturbo said:
Penelope Stopit said:
v8250 wrote "don't fit fuses to your fuel pumps as they can blow at the worst possible time i.e. on track/under fast driving...which you would not want
Over the years I have witnessed so many stupid things that have been said or done by so many people that should not be allowed to go near a car for any other reason than to drive it, the above comment could be found very funny if it wasnt so dangerous
Bizarre for sure !!Over the years I have witnessed so many stupid things that have been said or done by so many people that should not be allowed to go near a car for any other reason than to drive it, the above comment could be found very funny if it wasnt so dangerous
It would be idiotic not to fuse such circuits.
Nails instead of glass fuses was a good one, a nice big nail was a perfect replacement for a glass fuse, the result was fantastic
Max_Torque said:
Generally, for LV circuits, the fuse is to protect the wiring and not the consumer! IE, you rate the fuse well above the maximum current draw of the fuel pump, something like 1.5 or 2 x higher at least. The purpose of the fuse is to blow and prevent a loom fire in the event the loom is short circuited, which, in a car with it's chassis as one of the conductors is really very easy to do!.
Many years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
Good isnt it, things like this keep people in jobsMany years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
Ive seen plenty of new kit burnt out due to uprating fuses
Do any of you remember these ceramic continental fuses
The continental fuse prefered to glow red hot rather than blow, these babies have burnt out more stuff than scrapyard crooks
Penelope Stopit said:
Max_Torque said:
Generally, for LV circuits, the fuse is to protect the wiring and not the consumer! IE, you rate the fuse well above the maximum current draw of the fuel pump, something like 1.5 or 2 x higher at least. The purpose of the fuse is to blow and prevent a loom fire in the event the loom is short circuited, which, in a car with it's chassis as one of the conductors is really very easy to do!.
Many years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
Good isnt it, things like this keep people in jobsMany years ago, a military client of mine, refused to fit a fuse to a safety critical system i supplied, because the fuse might fail and hence risk the occupants lives. I suggested this was a false economy. They ignored me, and during trials with their prototype fighting vehicle, valued at around £2M, they had a loom failure, leading to a fire, leading to a total loss of the vehicle. I tried very hard not to say " I told you so", really i did. ;-) I had also suggested that risking squaddies lives probably would piss them off, but setting fire to them first wouldn't actually help matters much either.
Ive seen plenty of new kit burnt out due to uprating fuses
Do any of you remember these ceramic continental fuses
The continental fuse prefered to glow red hot rather than blow, these babies have burnt out more stuff than scrapyard crooks
Max_Torque said:
Those un-shielded fuses caused lots of car fires in the late 1970s and early 19080s when manufacturers first started to fit bulkhead sound proofing, which was made of flammable woven "fabric". The fuse would blow, a small white hot bit of burning metal would drop down off the fuse box, onto the bulkhead and, poof, your car would self immolate.....
First time I have heard this, noticed missing fuse box covers more often than not yet had no idea of the dangerstevieturbo said:
Remember ?
My car still uses them.
As long as you have a good nose you should be okMy car still uses them.
It was very common for rear looms to burn out before blowing the fuse, more often than not it would be a tail/number plate lamp wire shorting out down the back end somewhere. Due to the long length of the wire it had a bit of resistance and add to that the poor blow quality of the fuses, the long wire became a heating element from front to back
Just gently steering us back to swirl pots 
The comment from Steve at the beginning of the thread about cavitation in the HP pump inlet has struck a cord. We bought our 205GTI race car with a swirl pot already fitted (under the boot floor). It seems to work OK at all the UK circuits, except weirdly at Brands going around Graham Hill bend onto Cooper Straight where we often get noticeable starvation. Why just this one corner is baffling (pun intended
) but that could be a thread on its own. What concerns me about the current setup, is that the HP pump is level (give or take a few cm) with the top of the Swirl tank. Although there is logic to "if its ain't broke....", should I lower the HP pump to avoid it doing any lifting?
The comment from Steve at the beginning of the thread about cavitation in the HP pump inlet has struck a cord. We bought our 205GTI race car with a swirl pot already fitted (under the boot floor). It seems to work OK at all the UK circuits, except weirdly at Brands going around Graham Hill bend onto Cooper Straight where we often get noticeable starvation. Why just this one corner is baffling (pun intended
) but that could be a thread on its own. What concerns me about the current setup, is that the HP pump is level (give or take a few cm) with the top of the Swirl tank. Although there is logic to "if its ain't broke....", should I lower the HP pump to avoid it doing any lifting?ArthurH said:
Just gently steering us back to swirl pots
The comment from Steve at the beginning of the thread about cavitation in the HP pump inlet has struck a cord. We bought our 205GTI race car with a swirl pot already fitted (under the boot floor). It seems to work OK at all the UK circuits, except weirdly at Brands going around Graham Hill bend onto Cooper Straight where we often get noticeable starvation. Why just this one corner is baffling (pun intended ) but that could be a thread on its own. What concerns me about the current setup, is that the HP pump is level (give or take a few cm) with the top of the Swirl tank. Although there is logic to "if its ain't broke....", should I lower the HP pump to avoid it doing any lifting?
lower, reposition....either or.The comment from Steve at the beginning of the thread about cavitation in the HP pump inlet has struck a cord. We bought our 205GTI race car with a swirl pot already fitted (under the boot floor). It seems to work OK at all the UK circuits, except weirdly at Brands going around Graham Hill bend onto Cooper Straight where we often get noticeable starvation. Why just this one corner is baffling (pun intended
) but that could be a thread on its own. What concerns me about the current setup, is that the HP pump is level (give or take a few cm) with the top of the Swirl tank. Although there is logic to "if its ain't broke....", should I lower the HP pump to avoid it doing any lifting?If it's a vertical tank, the pump could go vertical beside it so the base/rotors of the pump are as low as possible, even if the outlet is high.
Or if the lift pump is adequate, in theory you should be able to run the swirl pot at a higher than ambient pressure....although that would need to be ensured it is always like that, as if it reduced then the high pump might be at slight risk of cavitation again.
TBH if it was me these days, I'd prefer in tank pumps. You know they're in the right place, and you know they're mounted as low as possible within the fuel ( when done right ) and they're neat and compact.
Whether it's a tank designed correctly from the outset, or the likes of a Nuke, Radium, 034 etc etc surge tank as an addition to a standard tank.
Thanks Stevie, I will lower the HP pump. I can get the inlet to the pump to be almost the same level as the outlet from the tank. Just for completeness, I should have said above that the LP pump is the original OEM submerged pump, fitted inside the original GTI fuel tank - but it seems to do a very good job.
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