Originally Posted by
JonnyBravo
I commented on someones install recently, was a stock tank under the car and swirl pot in the back so in that case returning to the swirl pot and the top of the swirl pot returning to the tank is how I'd plumb it in but he was told that was not right, by quite a good source too.
Whats your opinion on that ? is overheating the fuel that much of an issue ?
Depends on the setup. By returning to the swirl tank, you're effectively creating a heating loop with a very small volume of liquid.
So if the rails/engine bay is a very hot environment, then it is possible for fuel to get very hot. As to how much of a problem this might be I dont know, or how hot it would actually get. But it could get pretty hot.
But the simple reason people plumb it this way, is so they can get away with a much smaller lift pump.
If you use an adequate lift pump, then there is no reason at all to need to return any fuel back to the swirl tank. This also ensures no hot fuel at all is ever re-circulated into the small swirl tank.
It's just a simple design matter.
As far as temps go, Ive only ever monitored my own but I just run a large fuel tank, no swirl. But I have seen as high as about 38degC on a warm day with the engine running. ( do have a cooler on the return line, although it's very badly placed. But probably does help a little.
So I'm sure with a small swirl tank temps could easily get pretty hot.
Although if you do return to the swirl tank and also use a decent lift pump, it may have sufficient volume of flow to dilute the hot fuel from the engine enough that heat in the swirl tank doesnt become an issue
return to swirl tank = lift pump only has to flow enough fuel that the engine is actually consuming.
return to main tank = lift pump has to outflow the main engine pump at all times
It's very simple really.