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Old 10-27-2020, 12:39 AM   #233
brecks
Scooby Specialist
 
Member#: 435142
Join Date: Nov 2015
Chapter/Region: MWSOC
Location: Commerce Twp, MI
Vehicle:
2004 STi
Java Black Pearl

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Quote:
Originally Posted by KillerBMotorsport View Post
I'd want to see ~85psi or better at that RPM. If the pump is sized right, the pressure will scale up with RPM. If the pump is too big, pressure drop may occur.
Iíve noticed an oil pressure drop in the higher rpms that lead me back to this thread. Iíd read it before, but since you bumped it in April, I reread it... despite the pissing match in the middle, a lot of good info here. I see right around 85psi when the engine is warm once the relief valve opens (~3000rpm and beyond). The idle pressure hangs out around 24psi.
SAVCS 04 STi
Mains: 0.0017Ē
Rods: 0.002Ē
Oil: Motul Sport 5w40
Revving to 7200rpm
External oil cooler with 200į thermostatic sandwich plate, -10 lines, no OEM cooler.
DBB turbo with restrictor on feed
Stock 10mm oil pump, no added shims
Pressure measured at galley under alternator.

I understand my mains are rather loose compared to the numbers you like to use, but seeing as I couldnít reliably get this block line bored in a timely manner, it is what it is there. However, Iíve been noticing that at WOT, Iíll get an oil pressure drop past 5000rpms, typically from ~85psi to ~75psi. Iíve verified that my electronic gauge is reading correctly with a mechanical gauge, made sure the oil cooler setup isnít restricting (shouldnít be, as -10 is about the be same ID as the block passages). KillerB pickup and baffle, so no cracked pickup. I checked the pump prior to installing for any burrs as well as loose screws on the backing plate. 5000-5100rpm happens to be the range where my AVCS goes to 0, which I believe would allow for more oil flow, potentially dropping pressure? Iím somewhat stumped here, and given the info youíve posted, this could even indicate the pump is oversized, no? Itís been mentioned that using an 11mm pump on SAVCS is too much pump and leads to aerating/pressure drop. But in certain circumstances, could even the 10mm be too large for a single AVCS engine? The pressure drop doesnít really concern me, except for on the track where that 75psi can get closer to 65psi
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Last edited by brecks; 10-27-2020 at 02:52 PM.
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