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07-08-2016, 10:05 PM | #1 |
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
Location: Canada
Vehicle:2003 WRX w STI V8 |
Oil Pressure vs Clearance, need advice
Hey guys,
I built my motor with the following clearances Mains 1 0.0014 2 0.0015 3 0.0013 4 0.0014 5 0.0015 Rods 0.0019 Using Cosworth 10mm Oil Pump (probably 20k KMs on it max (bought it new) Current motor EJ257 has been running for ~1000kms Originally started/flushed out with 5w30 Rotella t6 5w40 for 800kms Oil Cooler Installed Oil Cooler flushed out with 5w30 Currently using Amsoil 15w50 Dominator Racing Oil Pressure at hot idle 100 Celsius: 11-13 PSI @ 950-1000rpm Oil Pressure at hot cruise 100 Celsius: 60 PSI @ 3000 RPM Oil Pressure at WOT (110C) 4-7k RPM: 74-78PSI *no oil leaks (from what I can tell) Cold start 97PSI Usually I idle at 100C, if its lower like 90C my PSI increases to 15-20PSI I never saw any flakes or anything like that on my first oil change. I don't think I have anything wrong. I just don't feel comfortable with the OIL PSI at my IDLE. If the rad fans kick on the pressure drops (typical, less RPM). No difference between T6 and Amsoil Oils. So I guess if you read this far, the question is, should I be worried? Should I put in an 11mm oil pump? Car has been driven tuned and driven to 15PSI on a 60-1 rotated setup. Thank you for your time! Ron
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Last edited by OC_Nooby; 07-09-2016 at 05:07 PM. |
07-08-2016, 10:10 PM | #2 |
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
Location: Canada
Vehicle:2003 WRX w STI V8 |
If an 11MM pump is required, no problem, I will do this.
AVCS will be used, I don't see any issue with this though as it will be triggered when I drive which I don't have an issue with. |
07-09-2016, 10:58 AM | #3 |
Scooby Newbie
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Join Date: Oct 2011
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Tri-State
Location: Long Island, NY
Vehicle:2004 Sti WRB |
I'm curious of the outcome. The hot idle does seem a little low but Im still learning so I'm not sure what it should even be.
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07-09-2016, 02:25 PM | #4 |
Scooby Specialist
Member#: 265430
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Vehicle:2005 OBP WRX STi IG/FB - seriousblacksti |
I was seeing 7-15 psi at hot idle on hot days with the 10mm pump on my built engine. This was using Motul 300V 15w-50.
Clearanes on my engine are as follows: Mains 1, 3 and 5: .0015" Mains 2 and 4: .0018" Rods: .0020" I switched to the 11mm pump and have yet to see below about ~20 psi at hot idle using the same oil. Cold start was ~95psi on both pumps, the 10mm just couldn't keep the pressure up when the oil was warm. Cruising around 3k I see 60-70psi with the 11mm. I was lucky to see 50 psi at 3k on the 10mm. |
07-09-2016, 03:23 PM | #5 |
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
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Vehicle:2003 WRX w STI V8 |
So i'm pretty much getting what you are at mid range but idle is where the 11mm will address my issue (looks like).
STISomeday, are you using a stock 11mm pump (oem not modified)? What pressure do you see at 7k? Did you shim it any? I'll be revving to 7.5k Max. Thanks! Last edited by OC_Nooby; 07-09-2016 at 04:56 PM. |
07-10-2016, 02:42 AM | #6 |
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Are you guys running AVCS ? Should use a 11mm then (IIRC)
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07-10-2016, 10:25 AM | #7 |
Scooby Newbie
Member#: 299478
Join Date: Oct 2011
Chapter/Region:
E. Canada
Location: Montreal
Vehicle:2008 WRX Black |
I assembled my engine with clearance very similar to yours, and I seem to also have low oil pressure at idle (~10 psi).
I recently had to pull the engine to fix a leaky oil pan, weld a bung for an oil temp sensor and replace the transmission so I also swapped the oil pump for a 11mm one. It did not help, I still have low pressure at hot idle. There was no metal in the oil pan when I removed it so I dont think that the bearings are damaged. So far I have put 5000 km on the engine without any problem. I am thinking to switch to 50 weight oil to see if it helps (currently running Rotella 5w40) Oh, and I am running WRX heads (AVCS on the intake) |
07-10-2016, 11:44 AM | #8 |
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
Location: Canada
Vehicle:2003 WRX w STI V8 |
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07-10-2016, 11:46 AM | #9 | |
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
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Vehicle:2003 WRX w STI V8 |
Quote:
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07-10-2016, 02:53 PM | #10 | |
Scooby Specialist
Member#: 265430
Join Date: Nov 2010
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Quote:
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07-10-2016, 07:22 PM | #11 |
Scooby Newbie
Member#: 299478
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Location: Montreal
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07-10-2016, 09:05 PM | #12 | ||
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
Location: Canada
Vehicle:2003 WRX w STI V8 |
Quote:
Quote:
I will order an 11mm Oil Pump from the dealership and install it. Will update the thread once this has been done. Thanks for all who posted! |
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07-11-2016, 10:24 AM | #13 |
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Vehicle:2006 frankenSTi OBP |
Im seeing around 15-20psi with my iag built motor running a 11mm oil pump with single avcs. Running motul break in oil at the time, Sometimes it drops down 13-15psi when the oil gets hot(running a perrin oil cooler). Not sure if the cooler actually helps or not
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07-11-2016, 10:55 AM | #14 |
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Oil pressure at idle won't change between the pumps. The 11mm pump has a higher volumetric flow rate but idle pressure is the same (rated at 14psi @600rpm.)
Running AVCS I would go to the 11mm pump...or even better the JDM 11mm pump. |
07-11-2016, 12:03 PM | #15 | |
Scooby Specialist
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Quote:
The minimum pressure rating/specification may be the same but the actual pressure produced in application is different. |
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07-11-2016, 12:30 PM | #16 |
Scooby Specialist
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Join Date: Feb 2012
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Should have the car running this coming weekend. I will post up the results but honestly do believe it will increase my pressure, it's a bigger pump.
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07-11-2016, 12:34 PM | #17 | |
Scooby Specialist
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Vehicle:2011 WRX WRB |
Quote:
These pumps are positive displacement. The 11mm flows more everywhere due to the rotor being larger. The faster you spin it the more oil is going to coming out. Also that number you threw out there is 14 PSI @600 rpm when oil is 80c Usually hot idle is when oil is 105c. I can confirm as well that going to 11mm bumps pressure. My 10mm pump would have oil pressure around 12 psi at factory idle running 20w-50 when hot. 11mm won't go below 20 psi running the same oil even after running the car extremely hard on back roads for 10 minutes straight. Usually its at 25-30 psi when very hot. |
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07-11-2016, 03:19 PM | #18 | |
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Quote:
The oil pressure at low RPM's is set by the restrictions in the flow path from the pickup to the head (system pressure). Unless your pump is grossly oversized causing a ton of back pressure, the system pressure is going to be the same, hence the value of 14 psi (est) given directly from Subaru seen below. A 10mm vs 11mm won't chance much at such a low RPM. Higher, yes.... but not at 600 RPM. Temperature, sure...but that depends on oil viscosity and can be vastly different between applications. 10mm 11mm Last edited by vwown3d; 07-11-2016 at 03:44 PM. |
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07-11-2016, 03:20 PM | #19 |
NASIOC Vendor
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Location: Virginia
Vehicle:2005 WRX/STi WRB of course |
If you're sticking to OEM or typical 'built engine specs', stay with the OEM size pump. If you have a pressure problem it can be a handful of things; pump not disassembled and checked (sticky, burrs, or both), internal leak, pickup seal or tube failure/crack (OEM) or faulty sender/gauge, sender is not in the front galley port, engine assembly/clearance errors...
The 10mm pump produces 10 more psi of pressure vs the 11mm pump, at high RPMs. The 11mm pump has higher oil pressure at idle because it's compressing the pump's bypass spring more because it's flowing more oil through the bypass... not the engine! Installing a larger pump will not push more oil into the engine, it will push more out the pump's bypass valve. Break-in oil is thin. Expect to run lower pressures. 11mm pumps do not perform as well at high RPM as the 10mm pumps. ESPECIALLY, then they are put onto an engine not made for them; non-dual AVCS. There are only rare occasions where you NEED a larger pump, and that's with really large clearances. To g along with that the pumps need to be worked over as well. Just my 2 cents. |
07-11-2016, 05:22 PM | #20 | ||
Scooby Specialist
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Join Date: Feb 2010
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Location: Edmonton, Alberta
Vehicle:2011 WRX WRB |
Quote:
Those numbers in the FSM are the minimum numbers. 7mm oil pumps also have the same 14psi @ 600 rpm at 80c. Oil at 80c isn't very hot at all. That would more likely be considered "warm" oil pressure. Quote:
I have main clearances between 0.0013 and 0.0015 My idle oil pressure with my 10mm was pretty low when hot with 20w-50 oil, 12psi after cruising on the highway. Cruising at 3000 rpm my oil pressure would be at 68psi. I got a boost of over 10 psi going to an 11mm at idle and that is after driving the hell out of my car with an ambient temperature 5c hotter. Cruising at 3000 rpm it is at 80 psi. I ported and polished the 11mm and added 1 shim. Relief pressure is very similar to the 10mm now as it stops climbing around at 80-90 psi depending on how hot the oil is. FWIW my 10mm would stop at 78psi. |
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07-11-2016, 05:57 PM | #21 |
Scooby Specialist
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Join Date: Feb 2012
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Hey Delphi,
How many shims did you have total? Clearances we seem to have the same, I know other components will change pressures but I'm curious on the shims. Ideally I should test as is and add if required. Thanks for all the good info everyone! |
07-11-2016, 06:34 PM | #22 | |
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Quote:
I added another. |
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07-11-2016, 07:51 PM | #23 | |
NASIOC Vendor
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Quote:
If you guys want to mask an issue with a bigger pump that's fine. It may even be buying you time. Personally, I'd rather have the smallest pump run the ideal pressure/flow. It adds the least amount of heat to the oil, less chance for failure (see broken oil pumps), and has the lowest parasitic losses. |
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07-11-2016, 08:36 PM | #24 | |
Scooby Specialist
Member#: 311781
Join Date: Feb 2012
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Vehicle:2003 WRX w STI V8 |
Quote:
Going from 40weight to 50weight has not changed anything for me. |
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07-11-2016, 08:37 PM | #25 |
Scooby Specialist
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