Originally Posted by heeman10
It's different when it's oil draining back from the heads as opposed to a turbo oil return as is being discussed here:
a) The turbo oil return is coming directly from high speed bearings, so the fresh oil supply cannot be hindered
i understand that, every car i have seen with an after market turbo install has had the returns mounted above the oil level
Originally Posted by heeman10
b) There is a much bigger pressure head on the oil coming from the heads on that engine. The oil leaving the turbo is doing so from no more than about 100-150mm or so above the oil level in the sump, hence all the talk of pressure differentials.
again, there could be various resons why the returns were plumbed back at the base of the sump, don't forget, there is also the natural way for the oil to return from the top end, the returns are there to stop all the oil staying in the top, but there must be a reason why they are below the oil level
on te other hand, we are talking baout oil coming from the sump, being pumped up to the turbo and then being dumped back into the sump again, if the oil were to stay above the line it would take longer to get to the turbo so pumping it below the line would serve as a way to fill the sump with a fresh resivour of oil for the pick up pipe to collect it from, a cirlce of life if you will
what you really want is a perspex sump to see how the oil is getting spun around the sump to get the best results