Can anyone tell me about these,

Do they have to be in the tank?

Can you fit one to the end of the pick up pipe?

Does the Sierra have one fitted as standard?

Is it only when the tank is low on fuel that they become critical?

Anyone got any pictures?

Thanks

Mark

Mark, are you running fuel injection? If not then good baffle design should suffice.
If you are, then a swirl pot basically acts as a float chamber, and can in principle go anywhere in the system. An integral one built into the tank is probably ideal in terms of simplicity, but if you propose to do some serious track days/racing, then a larger stand alone one with two fuel pumps is the best way to go IMO as integral pots on the bottom of your tank can be restricted in capacity. A standard lift pump supplys fuel to the swirl pot, and the high pressure pump taking fuel from the pot to the system. Fuel return from the injection system can then either be plumbed back into the swirl pot, or into the fuel tank itself.