Quote:
Originally Posted by 900BRZ
Thank you! Yeah I think those are interesting ideas. May need a new header to install a deeper pan, but that is a possible route to go down. Similar idea to a slight overfill. Doesn’t solve the surging/sloshing, but may reduce the impact.
I have read about some modifications to pickups to remove bends (I believe this was in a forced induction FA20). They argued that the bend was causing cavitation and, thus, starvation. So in general I’m hesitant about bends unless they have significant testing, which seems lacking even in the factory FA24.
In theory this pressure drop could be a result of cavitation in the irregularly shaped FA24 pickup rather than lack of oil, but it’s hard to say without more research. At this point, I’m hoping that the prototype baffle works and I keep can tracking this car for years to come.
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As someone who has spent 13+ years in the pump industry (specifically chilled water loops, heating and fire pumps), I would caution the implication that cavitation is the cause of the pressure drop. Given the way the oil system has to wait for oil to drain back to the pan, the oil pickup isn't pressurized. Correct me if I'm wrong, but in this case the oil pump actually has to
suck oil UP from the pan to pump it through the engine.
EDIT: Please note, I am writing this to add constructive feedback to the the diagnosis, I LOVE your critical breakdown and data. I mean no disrespect. You have provided by FAR the most data driven analysis of this problem. Many thanks.
From having seen internal documents within Subaru, they said they adjusted the shape of the pan to reduce frothing at the pickup. I assume this is more to ensure that consistent oil flow can be had at the pickup. This leads me to my point:
I think the issue is that the pickup is not reliably being presented with oil to suck up. The pump will cavitate as a result but the cause isn't the cavitation but a byproduct. If frothing was an issue, the easiest way to have fixed that was either to make the pickup go deeper into the pan where the highest amount of G doesn't affect it BUT you also have to consider the oil return coming back is actually hitting the spot where the pickup is intaking oil. If the G is high enough, maybe oil isn't flowing back to that spot. Short of seeing the oil paths, I am baffled (pun intended) as to why right turns don't allow for oil to return in enough volume back to the intake.