Upgrade Oil Pump to 11mm (08 STI design) - Worth It?

I need to replace my cam seals and timing belt on my 2005 Outback XT 5EAT with ~107,000 miles. I'm replacing the water pump and putting in a LWCP since I'm already there. While I'm in there, is it worth it to replace/upgrade the stock oil pump, too? I'm a bit inclined to save myself future time and hassle by upgrading it now, but I'm not sure if it's worth the ~$130.00.

 

If I can manage to save enough this summer, I plan to go Stage 2 after replacing the timing stuff. I plan to put in a catless up/down (keeping stock catback though)... and maybe a BNR 16G in a couple of years. I'm thinking it would be wise to upgrade the oil pump now.

 

I guess I'm hoping someone will tell me that it's not worth it so that I can rest easy while saving money, but I prefer honesty of course.

 

Product link: http://www.infamousperformance.net/servlet/the-1233/Subaru-EJ25-11mm-Oil/Detail

I'm doing it on my build... my gut feeling tells me that the 11mm helps prevent rod bearing failure. I am also installing a nitride crank on this build too like the mid '08STI+ got.

 

This is purely my gut feeling based on my own subjective experience.

 

Shaun

I just went with a new stock oil pump on my new engine. It's more about oil changes then it is about a new pump.

 

IMO If I were you, I'd put the pump you have back on. We ran the OEM honda oil pump with 216,000 miles on it on our 586whp Honda race motor. Had the machine shop check it and shim it for 100psi and never had a issue with it.

I just went with a new stock oil pump on my new engine. It's more about oil changes then it is about a new pump.

 

IMO If I were you, I'd put the pump you have back on. We ran the OEM honda oil pump with 216,000 miles on it on our 586whp Honda race motor. Had the machine shop check it and shim it for 100psi and never had a issue with it.

 

To be completely objective, a Honda oil pump may be different from a Subaru oil pump (though I see your point). The stock oil pump on my vehicle should be 10 mm, IIRC. Do you know what the Honda's oil pump size is? If Honda went with, for example, 12 mm to start with, then it may not be the best reference for OE vs. upgrade.

 

To any forum members running over 300 WHP on a stock oil pump, have there ever been any issues at all? Personally, I'll probably go no higher than about 250 WHP on my Outback.

 

EDIT: Just saw your sig.

 

However, for the sake of a larger sample size, the question still stands. Thanks!

There are lots of threads on the Honda forums about porting the oil pump for better flow. So I would assume like most porducts they were sized for what the Engineers thought would be the worst case. I'm sure they never pictured what we would do with those little engines. 216,000 mile oem crankshaft, knife edged and spinning 9500+ rpm.

 

The Honda pump works the same way as these pumps, it slides over the snoot in the crankshaft.

 

 

 

I can look at the part number of the pump Mike at AZP ordered for me. To be honest, he talked me into a new oil pump, I just said order and ship it to me. I was going to use the old one.

 

I checked the invoice, there was a mix up with paypal and there is no part number on the invoice. Not sure i still have the box either.

subcribed

If you plan on future mods, go ahead and upgrade the pump. I put a Cosworth 12mm on mine when I built it.

i recently spun a bearing in my LGT...rebuilt the entire motor and put an 11mm high volume oil pump in.

how much did your oil pressure go up?

JDM lgt oil pumps are 12mm if u can find one of those

Just some additional info for those considering an oil pump upgrade:

 

I came across an interview article online in my forum-scanning today.

http://www.importtuner.com/tech/impp_1103_subaru_ej_series_engine_tech/viewall.html

 

From the article, regarding bad advice given on forums: "Another [bad piece of advice] is about larger pressure/volume oil pumps are always better because the factory oiling system on the EJ motors are inadequate, when in fact, a high-pressure oil pump can cause oil cavitation while lowering the ability for any oiling system to work efficiently" [emphasis added].

^^ I was just going to say that. Its a good read too.

read this thread before considering using a larger displacement oil pump.

http://forums.nasioc.com/forums/showthread.php?t=2466900

 

the 08 sti oil pump is spec'd for a dual avcs motor and has a much lower bypass psi setting. that means that you'll be bypassing most of your oil around the motor in your upper rpm range, this is adding heat to the oil as well as aerating it un-neededly.

 

a larger oil pump is not something you just throw on when you build a motor, main bearing clearances, and a host of other things determine the flow requirements of your pump.

 

TL;DR

-talk to a reputable engine builder before changing your oil pump size.

^ this right here is correct

read this thread before considering using a larger displacement oil pump.

http://forums.nasioc.com/forums/showthread.php?t=2466900

 

the 08 sti oil pump is spec'd for a dual avcs motor and has a much lower bypass psi setting. that means that you'll be bypassing most of your oil around the motor in your upper rpm range, this is adding heat to the oil as well as aerating it un-neededly.

 

a larger oil pump is not something you just throw on when you build a motor, main bearing clearances, and a host of other things determine the flow requirements of your pump.

 

TL;DR

-talk to a reputable engine builder before changing your oil pump size.

 

I agree

Crap I guess i'm screwed then. Been running the 11mm pump for 20k miles so far on a fresh block. Oh boy..

I'm really screwed, I'm running a 12mm Cosworth.

 

Sent from my SGH-T999 using Tapatalk 2

We're ALL screwed now.

 

Pls everyone keep this thread up to date and most of all.. stay safe everyone

I'm 11mm too. Seemed like a logical idea. Subscribed.

I've too been tested positive for having Sti 11mm oil pump. I caught it while my engine was in the emergency room. I guess it was picked up through parts transfusion. I didn't know until I was diagnosed when I received my invoice.

 

5 months and 4,000 miles later, I don't have any ill symptoms or signs showing the disease, but I guess it's only a matter of time.

 

I have been going to these weekly Subaru meeting to help cope with my dilemma. Thank you everyone for any support, I appreciate it

 

 

Please stay safe.

 

Peace, love, and happiness

For you guys with the larger pumps, instead of removing it, just "upgrade" to a bypass oil filter setup!

Will this make me safe from the 11mm pump?

I can't really give you a yes/no answer(I'm not aware of any inherent problems with that pump itself); it just basically makes use of the "excess" oil it's pumping. Assuming you use something like C&R's bypass setup(adjustable), you may be able to fine-tune the oil system pressure so the pressure relief valve isn't being overworked.

On street cars the effects of the larger pump are not easily seen. Your pumping more oil so your parasitic losses may be marginally higher and the oil temps may be marginally higher. The problem becomes more aparent on track at sustained high load high RPM levels. The increase in flow through the bypass can cause aeration of the oil which causes pressure fluctuations.