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Old 05-07-2019, 08:32 AM   #1
Gamil
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Default 13mm Oil Pump???

Hi, rebuilding an EJ253 (2011 OBS with AVLS). In talking with the engine shop that I have decking the block/heads, valve job, etc, I mentioned that I want to rebuild the engine for longevity. It's retired from DD duties and will mostly be for AutoX and HPDE events with the occasional rallyX. They suggested going with King Race bearings with Extra clearance (part# KGNMB5382XPG STDX and KGNCR4125XPG STDX) and what they called a Rally Spec 13mm oil pump from Subaru.

With the extra clearance, I know that more flow is necessary, but 13mm sounds crazy excessive when the most extreme oil pump i've read about on NASIOC is a shimmed 12mm pump. He specifically said it was a subaru made pump for Rally applications, which to me means 8500rpm screamers that also pumps oil to a turbo, additional oil coolers, and other things that demand extra flow.

This shop does a lot of the work for the local tuning companies that build STI engines, so I think he's used to using such parts for 500+whp EJ257 builds.

But, the only mod to my engine that would require extra flow would be the extra clearance bearings. I plan to run it with Delta 1000 Cams and keep the factory redline of 6200rpm.

So, I'm here to ask
  • Is this 13mm "Rally" oil pump a thing?
  • It'd be overkill right?
  • Would an STI pump be good for me? (15010AA360)
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Old 05-07-2019, 09:25 AM   #2
BlackFighter
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He might be talking about Dave the owner of RalliSpec. IF he is then Yes he takes OEM subaru items and converts them in to pieces of rally art. I am not sure about a 13mm pump and if there is one then it might be a little over kill. I had a block from Dave and it took whatever i threw at it, and still run like new when sold the car. Also had Dave rebuilt my tranny and replace my gears with longer gears, loved it, didn't have to shift as often, perfect for DD and the boost curve was just like, hay do i shift now? ow no ok . Dave has been around for a while first building for Rally Subaru team cars then helping us. When he was building my block we agreed on 12mm oil pump.

http://www.rallispec.com

Last edited by BlackFighter; 05-08-2019 at 02:56 PM.
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Old 05-09-2019, 01:54 PM   #3
Gamil
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thanks for the response. Rallispec's inventory is basically a reflection of everything I've ready in these forums: 10, 11 and 12mm, with options for shimming. So I'll have to talk with this guy more and find out what he thinks he's got.
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Old 05-09-2019, 06:26 PM   #4
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13mm?! No, just no. At most a 12mm would be more than enough for your goals.
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Old 05-09-2019, 09:26 PM   #5
KillerBMotorsport
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The old adage used to be that loose was safe. That's really 10+ years ago. Not that it won't work, but we've learned a lot since then. Loose really only has a place in in environment where you're going from cold to full load for a short period; i.e. drag racing.

Builders used to mix and match bearing shells, not check alignment of the main bore, and because of that... run larger bearing clearances. Even from the factory, the main bore alignment is not great and clearances are tight Not ideal for excessive loads, but fine for OEM+ power levels. What is more common today, is blueprinting increases oiling capabilities. Line boring allows for proper bore alignment, which lets you right tight clearances on the main bore bearings. Tighter clearances means more oil gets to the weakest point on these engines, the rod bearings. Our spec engines run .0007 clearance mains for example.

I know of no 13mm oil pump. If there were one, I'd never recommend it, unless there were a VERY unique application that called for it. If the engine is built right, you shouldn't ever need to upsize the oil pump. Keep this in mind... at somewhere around 3K RPMs your oil pump will start pushing oil through the bypass. That means it's pumping more oil than can be pushed through the clearances. Additionally, as RPMs climb, that pressure will continue to go up another 15-20psi because there is such and excess of blow out the bypass valve that it is continuing to further open the bypass valve because of excessive flow. In short, the OEM pump has CRAP tons of excessive flow. Larger pumps have traditionally been used because other features, driven by oil flow, have been added. AVCS is a perfect example, as actuation consumes a tremendous amount of flow; under some conditions in excess of 20psi.

The Subaru oil pumps are positive displacement pumps. The flow more with RPM. I've seen a 10mm pump flow just fine to 10,000 RPMs, and there's no reason it couldn't go beyond that. What CAN happen with an excessively large pump is aeration in the bypass (as we see with the 11mm pump at RPMs above redline), additional head added (pumps add heat to oil), and additional parasitic losses (larger pumps take more power to compress more oil).

As far as rally cars go, most don't rev that high, and certainly not higher than stock. Class rules: stock class, restrictor class, etc., typically build a wall of torque (a lot of it) and then peter off after the turbo is out of the efficiency range around 6,000 RPMs. Open class you will see more RPM, but not a lot. I've not even seen the factory Subaru open class rally cars rev that high.

The other side of the coin is if you are working with a shop that has a time teste recipe for success, then you have to trust that.
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Old 05-12-2019, 02:47 PM   #6
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^^^+123 I agree with Chris^^^ Listen to the folks at KillerB...
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Old 05-13-2019, 02:48 PM   #7
Gamil
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Wow, that's some great info. Thanks!

Personally, I'd like to follow KillerB's advice on a tight blueprinted block, but that'd break the budget, and like you said, I should trust the shop's recipe. I'm not trying to make big power, just rebuilding an 150,000 mile NA 2.5L that's been retired from DD and needs to absorb the abuse that it'll be getting from Track Days, AutoX, RallyX, while also preparing for eventual Turbocharging.
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Old 05-15-2019, 08:58 PM   #8
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But it's a red flag if the shop says they have a 13mm pump and KillerB has never heard of it.
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Old 05-16-2019, 12:09 PM   #9
Gamil
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I've spent a fair amount of time talking with this guy and he knows a a lot about the different Subaru engines, what fits by year, different versions of rods and cranks. Even that MY06 saw the EJ253 changing over to a rod the same length as the STI. Saying 13mm may have just been a brain fart. I misspeak a number like that at least once a week.
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Old 05-20-2019, 10:06 AM   #10
BlackFighter
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That is all fine and dandy but is he still saying that a 13mm pump exists or is he saying i meant 12mm and it was it just a mix of words?
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