JAG Posted September 12, 2002 Share Posted September 12, 2002 I've been doing some reading up on fuel injected engines and have read several comments regarding swirl pots, though none have explained; what is the function of the 'swirl pot'? why are they fitted? where abouts in the fuel system would one be fitted? are all mass produced cars fitted with one? Any info would be most appreciated. JAG Link to comment Share on other sites More sharing options...
Peter Carmichael Posted September 12, 2002 Share Posted September 12, 2002 A fuel injected engine runs a pump constantly and any fuel that is not immediately required is recirculated to the tank. The excess fuel is vented through a fuel pressure regulator that maintains the fuel rail pressure at somewhere around 3-4 bar. If the fuel pump sucks air instead of fuel, the pressure immediately drops resulting in the engine stumbling or even cutting out. With fuel injection you need to guarantee that the pressure pump pickup is always immersed. A swirl pot achieves this. Typically, a low pressure pump is fitted to an unbaffled tank and this feeds the swirl pot. The high pressure pump is mounted in the swirl pot and because the swirl pot is tall and narrow, unlike the tank, it guarantees that the high pressure pump is always immersed. Link to comment Share on other sites More sharing options...
Tight fart Posted September 12, 2002 Share Posted September 12, 2002 I am no expert but for the fact that I have just had one fitted. the function in my case is to give a constant supply to the high presure pump. I changed fuel tank and was losing fuel pickup when cornering mine is on the rear bulk head (behind passenger seat) fuel tank >low pressure pump >swirl pot >high pressure pump >engine no idea whatsoever T.F@O.F. www.griptv.com Link to comment Share on other sites More sharing options...
scooby dooby doo Posted September 12, 2002 Share Posted September 12, 2002 FWIW the std installation seems to work pretty well. I had fuel surge on one track in Finland. I drove the mile or to the filling station and got 34 litres in each time.... I guess that suggests that no mods are really needed here. Unless its a hill climb special with only a cupfull of fuel - but you'd change the tank in that case anyway... HOOPY R706KGU CYCLE WINGS AEROSCREEN K SERIES CUCUMBER Link to comment Share on other sites More sharing options...
JAG Posted September 13, 2002 Author Share Posted September 13, 2002 Peter et al, Thanks for the info. By the sound of it a swirl pot is something you would fit to cure a fuel surge problem on a track car, is that correct? Does the standard Caterham installation include a swirl pot? What is the standard Caterham fuel injected installation? Does it have an in-tank fuel pump? Once again all replies much appreciated. JAG Link to comment Share on other sites More sharing options...
oilyhands Posted September 13, 2002 Share Posted September 13, 2002 A swirl pot (or surge pot to give it the correct name, swirl pot is something else) may well be required on a road car, it depends on whether the fuel tank is baffled and how susceptible is it to fuel movement on cornering. fuel injection systems have no reservoir of fuel like a carburettor so any interruption to the fuel supply however instantaneous will have an affect on the engines fuelling. If you are / have converted from carburettors you will likely need a surge pot. The standard Catrerham installation has an in tank pump. Oily There is more information here Link to comment Share on other sites More sharing options...
I.Mupferit Posted September 13, 2002 Share Posted September 13, 2002 As Oily says if you are changing from carbs. to injection, as I will be this winter, you need a swirl pot. The only alternative would be for me to renew the complete tank but the swirl pot is cheaper and as it rather conveniently solves any potential fuel surge problems at the same time it is, IMO, the best route to take. Brent Link to comment Share on other sites More sharing options...
JAG Posted September 13, 2002 Author Share Posted September 13, 2002 Brent, Oily - thanks for the info. should I fit a small low pressure pump to fill the surge pot? or fit the surge pot at the same level as the fuel tank and allow gravity to fill it? does either have an advantage? except saving the cost and complication of a second pump of course! JAG Link to comment Share on other sites More sharing options...
I.Mupferit Posted September 13, 2002 Share Posted September 13, 2002 You will definitely need a pump to fill the swirl pot. I will simply use the Webcon pump which presently feeds the DCOEs then buy a new high pressure pump for feeding the injectors. Brent Link to comment Share on other sites More sharing options...
aph Posted September 13, 2002 Share Posted September 13, 2002 on a golf all they use is a high volume/low pressure pump which is immersed in the tank and pumps directly from the fuel, feeding a highflow/pressure pump and then 2 a pressure acumulator with no swirl pot at all not sure if this helps or is relevent. The helper pumps are available separently if you need one Link to comment Share on other sites More sharing options...
Trevor Phillips Posted September 13, 2002 Share Posted September 13, 2002 What pressure would you run the low pressure pump at? Would something like a Red Top be suitable? Link to comment Share on other sites More sharing options...
EFA Posted September 13, 2002 Share Posted September 13, 2002 Trevor, The low pressure pump needs to be low pressure/high flow. The red top is ideal, if not the best choice. All factory injection caterhams have an in tank pump, and the tank is baffled. In all but extreme conditions (such as trying to doughnut with only 2L of fule in the tank, as I did at Le Mans, to many peoples amusement) it will work 100% even on track. You will only need a swirl pot (which is the wrong term, but everybody uses it) if you run an unbaffled tank such as a bag tank, or a tank from a carb Seven with a fuel injection system. Fat Arn Visit the K2 RUM website See the Lotus Seven Club 4 Counties Area Website here Link to comment Share on other sites More sharing options...
Dave M Posted September 13, 2002 Share Posted September 13, 2002 Surge tank schematic here Works a treat on my car. Link to comment Share on other sites More sharing options...
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