A discussion of Oil Pumps, Oil Pressure, and Shimming Subaru pumps

A few days ago, our friend and fellow racer Victor Kuhns from DM Rally was in town, and he has been working on building up a new engine for his race car to run up Pikes Peak. One of the aspects of his build that we have been talking about and helping him with has been the oil pressure on his new engine, and Victor has done a tone of testing of different oil pumps and configurations. He has found a lot of good information now that he has tried a number of different set-ups, and we were able to talk to him for a bit about all that he has now found out.
One of the most interesting things that we discuss is the process of putting a shim into a Subaru oil pump.
Thanks for watching, and a very big thank you to Victor for spending some time with us!

[@obancameron]

Sum up: increased tolerances (bigger bearing clearances)= need more volume (bigger pump) Increased RPM= need more oil pressure (using shims or stiffer springs) Viscosity is resistance to motion. If the viscosity is reduced the oil flows more freely, i.e. faster, and hence the static pressure is reduced. Increase the viscosity and the oil is flowing slowly and the static pressure increases. Heavy oil (15w40/50 etc) is more viscus so it resists flow and acts as a better cushion for your bearings (hydrodynamic suspension) but as the oil heats up past it's operating range the viscosity will drop and the the oil will flow easier and not hold pressure as well. You can increase the oil pressure and volume all you like but really it's the temperature change that causes the pressure drop and everything being done in the video is a common band-aid in motorsports that is just not as good as just reengineering the oiling system including better temperature control.

[@patonbike]

I have an old SOHC EJ25 w (stock 7mm pump) I like to rev out to 6500+rpm preferably 7000 but I haven't dared to go there yet because I am losing oil pressure in the 6000s. Everything is great until somewhere in the low-mid 6000s where it goes down perhaps as low as 50-55psi (hard to tell with it bouncing around and I don't have datalogging on it yet). I am thinking about switching to a 5w50 from 5w40 and/or changing to a 10mm relief spring. Do you have any thoughts on this setup? My understanding is that the stock relief is 70psi on the 7mm pump.

[@obancameron]

First: the blowby at higher rpm can cause issues so I'd move to a full race setup where the ports are vented to atmosphere or catch can that you check and empty after high tom runs. Second: Port match the oil pump and shim it, look up what the Tomei aftermarket pump has done and replicate that. Third: add an oil cooler and change to thicker oil, or substitute 1l synthetic oil additive (lucas synth etc) in your oil changes so it's 3 to 1 with 5w30 and additive Watch psi gauge after each change and don't do them all at the same time. This will show you what worked for your engine the best

[@vgnfab]

Great video guys! I'd love to lend a tip: You can add a system relief Anywhere in the system! So no need to remove the oil pump to shim it. In fact, any Subi could get a 12mm pump, shim it quite a bit, then add a nice adjustable relief at the back top end of the block after the main stretch that delivers oil to the crank.

[@HeidiFegles]

Funny you mentioned that. I am doing that but it goes through an oil bypass filter before returned to the oil sump. That’s why I use the 12 mm filter that bypass filter, and I have an oil cooler as well. you can tune the flow to the exact pressure you want and keep cavitation at bay. With the bypass filter flow

[@ttamn92]

Everyone puts so much importance on the oil pressure and just think a bigger number is better but the actual requirement of oil pressure is not only dependent on the volume of the oil flowing all the way through the engine without any cavitation or starvation occurring...as long as you have a good consistency of flow and volume the required pressure is drastically reduced....

[@pclife5603]

Just in time for my engine build. I definitely need this. Great video, good prospective coming from someone who knows whats in his engine.

[@FlatironsTuning]

Glad you found it, and thanks for watching!

[@MrGsxrme]

You guys definitely hit on a topic that's really not discussed on the internet. Most information you find on the internet just factory engines using factory clearances & people are relying on temp readings only. I personally have a built engine that I built a little looser on my main bearings clearances and I'm currently waiting on my oil pressure gauge to come in on shipping for this exact reason. Once bearing clearance has been changed oil pressure gauge must be used. I have only tuned my cold and warm start idle. Once I receive my oil pressure gauge then I will continue my tune. End of discussion.

[@FlatironsTuning]

Thanks for your comment. Glad that you found the video and that it was helpful. Thanks for watching and Stay Tuned!

[@RacerDave]

Excellent insight! Thanks Victor and Flatirons Tuning!

[@FlatironsTuning]

Thanks Dave!

[@derrickquintal]

Absolutely awesome and informative video!! You guys regularly make the best videos out there thank you!!

[@FlatironsTuning]

Thanks Derrick, and thanks for watching!

[@KvotheYSL21]

VERY Good information!!! Thank you!

[@r0kha465]

Thanks guys, another great video!

[@EmotionalTree]

Bang on with the pump upsize. I had to do the exact same thing except a 10mm to an 11mm. There is a certain company out there that is very against changing pump sizes from the one that came on your engine. I personally don't agree with that and shouldn't be used as a blanket statement.

[@FlatironsTuning]

Thanks for watching, and thanks for your comment.

[@BrianBattocchi]

Great video as always. The need for 12mm pump was required only after the bearing tolerances were increased correct? What drove the increase in bearing clearance if the 10mm pump was adequately filling to tighter bearings? I'm also curious where oil temperature was being monitored. I would guess these are sump or filter temperatures? When monitoring rear case temps on my ej25d na motors, I found the oil temp would continue to climb on long stages. It was not the highest quality gauge/sensor but still tended to show a relative increase over long stages. I've wondered if the tight bearing tolerances on stock motors don't flow enough and possibly the oil is getting hot while traveling between the pump and bearings. Basically the oil might be heat soaking in the block. Another thing about the ej25ds(probably not an issue on the 207s ) is they don't provide equal oil flow to all of the crank/rod bearings. If I remember correctly, two of the rod bearings share a single oil port while the others get their own. My last rod bearing failure was on one of the shared ports. Cross drilling or through drilling might help with that issue. Another thing that you probably have covered already is that those philips head oil pump screws should be lock tighted. They like to come loose. I've been struggling to find the root cause of the never ending rod bearing failures on these motors. Obviously oiling is a big part of that. Thanks again for sharing.

[@FlatironsTuning]

Thanks for your questions Brian. I believe that the oil temp is being measured off of the rear galley plug, but I'll have to check with Victor. The reason that the bearing tolerances were loosened was because the power target for the engine was increased by a fair amount. And yes, the need for the larger pump stemmed from that change in bearing tolerance. Thanks for watching!

[@BrianBattocchi]

Thanks for the info! I'm curious about the rational behind increasing the tolerance when increasing power. Is the idea to increase the oil pad thickness to cushion higher impact forces? account for increased flex? Something else?

[@FlatironsTuning]

Hello Brian. That is exactly the thought. Since the power goal was going up a good bit, the idea was to go with a slightly loser tolerance to give more of a cushion to the bearing. And to get that to work you need to maintain the target oil pressure, and that is where it got interesting :-)

[@BrianBattocchi]

Ahhhhh great info thanks!

[@AmirPomen]

u can use double drilled crank AND king crank bearing..because that particular brand have 360 degree oil groove and multiple oil hole on the bearing surface....every small change in improving that lubrication for conrod no.2 & no.3 does helps reducing the risk of broken conrod bearing

[@AmirPomen]

Bringing up another step... U guys can compare 10mil vs 12mil pump that already ported (smooth out sharp edges and chamfer) on the oil pickup side all the way to the rotor chamber.... Im sure people wants to know how it react in term of pressure and flow by increasing the suction side efficiency

[@FlatironsTuning]

Thanks for the suggestion. We'll add it to the list! Thanks for watching and Stay Tuned!

[@ReygnMotorsport]

Great! Thank you guys!

[@crpreludeh22]

Really helpful video!! Thanks guys

[@strifefaction]

Coming back to this with more questions/info. Engine rebuilt 2 yrs ago after the cooler fiasco. Running well enough still not fully tuned up to the goal of 400whp. Oils pressures 15w50 500~550kpa(72-79psi) from 3k-7.2k rpm. heat dependent All the way up to a temp of 90c is all it's gotten to (temp taken from pan) Im running 2 shims from what I remember. (could be 3) dont remember current curiosity wasnt noted until recenetly. But at sustained high speed 100+ and high 6k+ rpm. 2mins+ I BELIEVE Im getting some cavitation in the pump. Pressure starts to bounce quickly about 20-50ish kpa(3-7psi) maybe a bit more?(10psi?) Hard to keep my eye on it while going that fast. Unsure whats causing the cavitation. Maybe the pan/pick up unable to keep up with the demand(?) Or my catch can system is pulling so much vacuum on the breather system it's keeping oil in the heads and they're not draining back(?) (catch can does fill up after these types of runs maybe a restrictor in the catch can line could be a soultion? Or perharps swapping the head breather line to the pcv vac instead of it being on the turbo inlet vac line) maybe my issue is this is just not a wangan mobile lmao. Wish I could talk to this victor guy or he'd chime in with more specific knowledge.

[@FlatironsTuning]

Thanks for your question. 2 minutes is a long time to spend above 6,000 rpm, and at high power, etc. The longer you spend at WOT, the more likely you are to over-tax your AOS/Catch Can system, and that is most likely why you are seeing full catch cans after this kind of run. I'd recommend looking into some kind of system that will allow you to data-log your oil pressure at a minimum (ideally you would want to add in oil pressure and crankcase pressure as well) so you can see what is actually going on in those conditions. I'd have to assume that your oil temps would be increasing in that long duration spent at high rpm. Hope that helps and Stay Tuned!

[@strifefaction]

@@FlatironsTuning Ah yeah I should probably stop ringing it out like that as I didn't build it for that type of driving more of a wild canyon carver during which this type of pressure fluctuation doesnt occur or isn't noticed I suppose. My oil temps are taken from the pan (moroso Aluminum racing pan) temps stay sub 70c During these runs.(given night and cooler ambient temo) Even on hot days (80-100f) if the car is moving the temps stay sub 80c(usually sub 70c if freeway cruising) while moving and only creep up to 90c while not moving but drop as soon as it's flowing at a higher rate again but perhaps Im getting false readings(?) Maybe air is cooling the temp sensor as the pan sits lower than the bumper line so lots of airflow right by the sensor. Maybe I should add a sensor to the rear of the block? Lots of conflicting opinions on where oil temps should be taken from. I've got a defi link set up I think it has the capability to record short stints of data. Tho I'd only have data for my h2o/oil temp, oil press, and boost will have to figure out how to log/access it.

[@2003wrx64]

​@@strifefactiondo a Google search of "TK383 oil pump" and you'll get a hit on Nasioc "Oil Pump Question For Experts." In this discussion an Australian builder that goes by TK383 discusses oil pump cavitation at high rpm and claims that the biggest restriction is on the pressure side of the pump before the relief valve. It's post #9 in the discussion.

[@SuperJuniorja]

Awesome video very informative !

[@burtcokain2702]

Great info, always wondered about this, never really trusted what people say on the forums. Thanks alot guys!

[@FlatironsTuning]

Thanks for watching Burt!

[@robinsontanner1234]

At high rpms you will see a pressure drop due to less oil being in the pan and there being a shorter column of oil left in the oil pickup. It takes more force to pull that up which will lower your pressure. A higher outputting oil pump will actually increase that effect because there is more oil being used throughout the engine.

[@justin1234go]

No

[@obancameron]

No

[@woodzy575]

You could talk about water pumps and the high flow 21111aa026 for the early wrx vs the open impeller pumps. video idea🤔

[@petkokrushev3840]

Please correct me if I'm wrong, running 12mm pump in stock clearances without additional oil cooler will result in oil temperatures getting high?

[@FlatironsTuning]

I wouldn't say that would happen absolutely, but it is a possibility. Running a significantly larger pump than is required will mean that the relief valve will be open for a much higher percentage of time, and that can lead to an increase in oil temperature and some other issues. Hope that helps, and Stay Tuned!

[@5501pickopicko]

Just out of interest, do you know what oil clearances were given on the guys engine build, main and rod bearings if at all possible?

[@FlatironsTuning]

Thanks for your question Sam. They were very firmly on the lose side, but I don't remember the specific numbers. Thanks for watching!

[@5501pickopicko]

FlatironsTuning No problem, Thanks for the reply. Really useful set of videos your making by the way, keep up the good work 👌

[@FlatironsTuning]

Will do! We haven't had much time lately, but that should change here soon. We have a lot of catching up to do so stay tuned!

[@adamblaha9838]

Hello, great video guys! I have a few questions about the pump size...WRX 2001 EJ205...when my engine failed after I bought the car, I decided to build the engine with 12mm pump thinking "the more oil press, the better..." Man who built it for me is used to build the engines with increased tolerances. I use Castrol 10W60 and have 30 thousands kilometers on the engine. Should I have a worries about it, maybe cavitation or whatever? Oil gauge located on turbo inlet, 2.6bar@90deg celsius on idle, 6bar@90deg celsius while driving. Spec-C crankshaft with cross-drilled crank pin. Approx 300BHP. Should I go back to 10mm or 11mm? Engine seems to run really smoothly. Thanks a lot!

[@FlatironsTuning]

Thanks for your question. With that many miles, I'd have to say, if it isn't broke, don't fix it :-) Keep in mind that the larger pump will give you more volume, not pressure. Peak pressure is controlled by the relief valve spring, but the larger rotor will get you to that peak pressure faster. If you are running loser tolerances, then you would need a larger volume pump to maintain pressure, so since it sounds like that is what you have, I think that you have the correct pump. If you were having any issues with pressure, what you would see is a fall-off in the upper rpm range as we discuss in this video. Hope that helps, and thanks for watching!

[@mattoaida]

Great Video! I’m just still confused on one thing. Why does the oil heat up so much going through the bypass? I know friction was mentioned but doesn’t friction happen in the oil pump too?

[@FlatironsTuning]

Thanks for your question Matthew. Yes, friction does happen in the pump. When the relief valve opens, the oil that just went through the pump gets re-routed back to the inlet side, and goes through the pump again. If the oil get sent thorough the pump over and over, that is what can cause the oil to heat up. Thanks for watching!

[@al3zmi]

i have a question, i am looking at new oil pump but it asking me to choose how many shims, i already bought not installed yet is oil cooler and oil spacer and soon going forced induction so do i need to increase oil pressure before installing or can use a stock oil pump

[@FlatironsTuning]

Thanks for your question. The best answer I can give is that the relief valve pressure only adjusts your maximum oil pressure. If it is set to 85 psi, once your are at normal operating temp, that should be the highest oil pressure you would see. As far as what you would need to do with that maximum pressure when adding forced induction, I can't say. Hope that helps, and Stay Tuned!

[@al3zmi]

@@FlatironsTuning i was thinking increase pressure because it needs to be in more places like oil cooler and added turbo cuz it also needs oil for the shaft. but i wanted to know if it's nesscery or not, haven't found answer with forums, thanks for the reply!

[@FlatironsTuning]

@@al3zmi Okay, remember that all the shimming does is to control peak pressure. If you are adding extra demands on the oiling system (like a turbo for instance), this is where you may need a pump with extra volume to get your oil pressure up to that peak pressure as quickly as you would like. Since you are adding this onto your oiling system, I would either check with a shop that has done that change and see what they recommend, or if you can't do that, keep a close eye on oil pressure as you run the car for the first few times and make sure that you have sufficient pressure at idle, an lower rpm's, etc. Hope that helps and Stay Tuned!

[@strifefaction]

Looks like I'll be just trying the 12mm with 1 shim as well I'll be running .01" undersized bearings mains and rods forged internals and plan to rev the piss out of it. I have gauges to monitor as well if Im seeing over 100ish psi I'll drop my oil weight down I guess.... lol.

[@samwashere1392]

hey you have any info on how your engine build is running? what pressurestemps are you seeing?

[@strifefaction]

@@samwashere1392 ran pretty great for ~2000km till a contamination happened during a cooler install which ended in a spun big end bearing in the process of a rebuild right now . with stdx main and rod bearings and mobile 1 15w-50 Was seeing 800kpa on cold start. 400kpa freeway cruising 3.5- 4krpm 80mphish (with my moroso pans extra capacity and minimal passive coolingl oil temps never rose above 40C and were usually bottomed out ) spirited driving it was basically between 450-500kpa depending on oil temp as it rose up to 100c I was losing a tiny bit a pressure down to about 430kpa but still within what is considered acceptable for a stock psi. Cooler was put on to keep my oil temps around the 80c area but yeah didnt work out for me in the end :/. But by the time I was getting to 100c oil temp my water temps were also rising above 100c at the same time which could be contributing to the issue so I'd be backing off at that point anyways until it cooled back down. This is all while driving in the 5-7k rpm range for 10-15mins straight on a mountainous road with changing inclines and all which Im sure is a bit harder on cooling in general. Next set up will be a 12mm pump 3 shims total and i'll be using half std and stx mains with stdx rod bearings in hopes of maintaining above 450-500kpa with a rise in temp up to 100c+ as I ideally shouldnt be seeing a drop below the 450kpa and hopefully will be able to run a bit thinner oil on the daily and thick when I get to Finally track it. I think that should cover your question but lmk if you'd like to know anymore! 🤘🏻

[@samwashere1392]

@@strifefaction thank you! Lots of good info! What happened with the oil cooler contamination? Something of outside influence? What motor do you have? It’s in the GC8 on your channel? Non avcs, single or duel? I guess your not worried about the added oil bypass with the 12mm pump and std + stdx bearings?

[@strifefaction]

@@samwashere1392 After I tore it all apart I found a couple tiny pieces of Stainless steel mesh that Likely got into the 10an lines while I was cutting them apart to build the set up. Sad as I flushed all the lines with a hose that has pretty "high" pressure so 2-3 minutes each but wasnt enough to clear them fully it'd seem and I suspect the went thru the crank into the big end bearing and damaged it enough to not knock immediately but as I was trying to diag the very low oil pressure which was sub 200kpa at all times usually less than 100kpa at idle.(was 200kpa prior to the install while still running good ) the low pressure combined with total lack of power and all my Fluid temps rising suuuuper fast I should've know to just stop and take it apart right then but it eventually fully spun the big end bearing within the next day on a short test drive.. Yupp in my gc. Was suppose to have a video out going over the whole incident/tear down but most of the footage got lost/over written. So I'll be filming a new one soon with a some explanation and then a timelapse build/ reinstall. brief build overview v7 207 so single avcs with stock cams and valves. Built bottom end with Carrillo Pro Super A beam rods and 92.5mm Toda Racing pistons. And a Garrett GTX2867R Gen 2 with an 11 blade wheel. Id1300x , catless invidia dp and catless Hks hi-powrer. So with the 2 shims I wasnt getting any by-pass from what I could tell with stdx main and rods but given Im going to be using the half std/stdx mains this time Im going to add one more shim to negate any possibility of bypass. Ideally this should allow me to have better pressure throughout the useable temp range of oil as getting drop off at 100c seemed a bit premature as that's oils heavy weight rating temp so should still be performing properly to A bit above that ideally.

[@samwashere1392]

@@strifefaction thank you so much for all this actual real info!! I’m trying to put this engine together for a friend…we’ll see how long it lasts lol. Hope to see your next video soon!

[@FirstAidIndustries]

Hi there. Great content thank you. There were a few mentions of increased tolerances for bearings / journals. I'm assuming that's both mains and big ends? Are the tolerances much larger than the factory tolerances? I.e if a crank ran a bearing and was re ground to a point where most engine rebuilders would put undersized bearings in, could we Possibly get away with using standard size bearings intentionally to get that extra tolerance?

[@FlatironsTuning]

Thanks for your question. Above all, I'd definitely recommend working with your engine builder on this one. If your crank can be machined to a very precise tolerance, it could be possible that using a standard size bearing on the machined crank could give you the clearances that you are looking for. Again, a lot of that is going to come down to the machined specs of the crank. I hope that helps and Stay Tuned!

[@pabauza]

The discussion is a bit over my head but great video.

[@smee1198]

Hi! Where did Victor install his oil pressure and temp sensors in the engine?

[@alexudolkin2146]

Would a lightly modded EJ255 benefit from an 11mm pump? 2010 Single AVCS stock internals with killerB pickup and STI oil cooler. Thank you for the great content!

[@FlatironsTuning]

Thanks for your question. As you increase the volume of the oil pump, it means that your pressure will build faster. But that also means that you will hit your relief valve pressure sooner (think at an earlier rpm). So if you have a much larger pump than you need, then the oil will spend more time going around the relief valve. So as a general rule, we recommend using the pump recommended by Subaru until you make any changes to the oil clearances where you would need the larger pump to maintain the normal target pressure. I hope that helps and Stay Tuned!

[@mankalute4565]

Personally I didnt see a correlation between adding more shims and increasing pressure. Pressure will ultimately be determined by how ever much the clearances allow/create. Once you hit that it wont go up with more shims as this convo leads you to believe.

[@FlatironsTuning]

Thanks for your question. The relief valve ship increases the pressure on the relief valve, which in turn increases the maximum oil pressure that the pump will send into the system. Now the volume of the pump has to be sufficient to create that pressure with a given oil weight, and temperature. It can increase the maximum oil pressure in the engine, but the clearances of the engine, oil weight, and oil thickness (at a given temperature) all have fall into the proper condition to allow the pump to create that pressure. Thanks for watching and Stay Tuned!

[@lauwelau27h]

Very nice discussion! Do you maybe have a log/histogram of the oil pressure vs. engine speed? I've been working on my engine and I already see max pressure (90 psi) at 2500 rpm using a 10w40, listening to this I see that this might lead to heating up the oil more than needed due to the bypass it has to be pushed through. Is this a risk you think? I do have to say that it is still a fresh build and the engine did not break-in as of yet, so I suppose the graph I see will probably move too a higher engine speed as the the break-in progresses (first instance of max pressure moving towards higher rpm I mean by that). Thanks

[@FlatironsTuning]

Thanks for your question. We don't have a graph of pressure in this case. I will say that when you first start your engine, it is completely normal to see high oil pressure in the 90 - 100 psi range. The heavier weight of oil you are using, the higher this pressure will be typically. You definitely want to pay close attention once the oil has heated up to operating temperature.After say 15 minutes of driving or so. From that point on, you will have a clear picture of the oil pressure you will see during normal operation, and from that point on, you can decide if you are comfortable with it, or if it might require some changes to get it where you want it to be. I hope that helps, and Stay Tuned!

[@stickman-1]

No mention of the loss in HP. Making the engine pump more oil at higher pressure has to lower the usable HP to the wheels. Maybe only a few, but maybe more. I expect more.

[@oky69]

Having also a built my EJ207 myself with race bearing clearances and a 12 mm pump I noticed two codes being thrown . They were camshaft position sensor B (P0390) circuit bank 2 and (P0365) bank 1 . My tuner informed me that cams were phasing correctly with no issues , my question is could increased in pump pressure and volume throw the codes in question ?

[@patonbike]

A bit confused as to how (or if) shimming the spring changes things at pressures significantly below the existing relief pressure. If the factory pressure relief is 75psi, wouldn't shimming the spring only make a change if you were already seeing right around 75psi (or greater) ? If you were only seeing 60 psi hot isn't the relief not doing anything at that point and thus a change to the relief spring wouldn't change anything?

[@FlatironsTuning]

Thanks Patrick. This is a great question, and you are thinking of this correctly. The relief valve spring is only controlling your peak pressure. Once you hit that ceiling (say 75 psi), the valve works to maintain that ceiling pressure. But if there is an issue with the pump such that it can not get to that pressure, raising that limit will not make much if any difference to where the problem area is. Thanks for watching the video, and Stay Tuned!

[@patonbike]

@@FlatironsTuning Thanks for the additional explanation!

[@turbosupra420]

Great video. Love watching your stuff. I have recently built a EJ257 with a RCM 12mm pump. My oil pressure was around 65 to 70psi and was happy with that. But then I installed a CSF rad with cooler and saw a pressure drop to 50psi and am very concerned about it. Oil temps are great Around 90°C. Would you recommend shimming in my case? Thanks for any help

[@FlatironsTuning]

Thanks for your question. That is a little odd. If you put a shim in the relief valve, that will raise the peak pressure where the valve would open. But it would not make any difference if you are below that pressure (which 50 psi would be). If you had the issue after running the oil through the CSF radiator and cooler, I'd recommend going back to your previous configuration. It makes me wonder if there is some kind of issue that is being caused by that cooler. Hope that helps and Stay Tuned!

[@turbosupra420]

I work at a subaru performance shop and we have been seeing oil pressure loss of 10 to 15 psi with the csf rad and cooler combo. Do you think 50psi is to low

[@FlatironsTuning]

@@turbosupra420 If that is at full throttle, I would say that is too low honestly.

[@turbosupra420]

@@FlatironsTuning is there another way I can talk to you. Would like to pick your brain a bit

[@FlatironsTuning]

@@turbosupra420 Sure, reach out to us on Live Chat on the site www.flatironstuning.com

[@shaneil7901]

Hey great video, please can you tell me when sealing up the plug for the shim and spring, do you need to apply any liquid gasket on it?

[@joshr8680]

What was oil pressure after adding 1 shim to the 12mm pump?

[@robk5745]

I think too many tuners run out to grab bigger pumps thinking its better. Here's a guy that ran a race motor with 10mm for a long time, not until larger hp numbers and clearances came into play did he have a drop. Most guys with light mods need to stick to the stock pump.

[@FlatironsTuning]

Thanks for the comment Rob, and that is pretty much the conclusion that we came to as well. Thanks for watching, and Stay Tuned!

[@Booki89]

Fantastic video as always! I have been doing some reading about the EJ25, specifically how there are alot of rod bearing failures. Now a rod bearing failure is primarily an issue with the oiling system - some cases the engine was run low on oil. But lots of cases where it was not run low on oil and poor tuning was not the cause. Where I am going with this is, there are some threads about porting/smoothing out some oil galley's on the block/oil pump. Have you tried this? Does it increase the reliability of the EJ's oiling system?

[@FlatironsTuning]

Thanks for your question! Bearing failures are definitely a tricky one. From what we have seen, I think that oil level is the leading cause, but it can be for a few different reasons. Specifically, running the car low on oil, oil consumption, and issues with the PCV system all can come into play. But yes, modifying the oil pumps is something that certain builders will do. Cosworth had a Blueprinted pump, and Roger Clark goes through and blueprints them, and replaces the pressure relief valve with one of their own design. It can definitely be helpful, but there are a number of other things that you would want to watch as well. Hope that helps, and thanks for watching!

[@Booki89]

@@FlatironsTuning What are your thoughts on the increased failings around the 08 year? Some people say that the casting on the oil ports of the case's were not quite as good as the older years - and were later rectified? Its a bit of a strange theory - as if this was the case wouldn't failure happen quite quickly? As long as the pickup is sucking the oil up - there should be no spun bearings.

[@FlatironsTuning]

@@Booki89 Nope, it was actually the bearing material. They had to remove the lead, and didn't fully account how much of a change that would make in the bearings. The fix was the heat treated cranks/nitride treated cranks, and now that they have switched to those across the board, there hasn't really been an issue.

[@Booki89]

@@FlatironsTuning The more you know! How did removing the lead effect the bearing's? Did they have different expansion characteristics? Would using after market bearings solve this issue if using a older style crank?

[@Clearanceman2]

Is there any adancatage to using a bigger volume pump on a non turbo subaru? Stock is 7mm.

[@FlatironsTuning]

Most likely not. Adding a larger volume pump just means that you will reach your relief valve pressure faster, and spend more time with the relief valve cycling pressure around the pump. In short, if you are not having any pressure related issues with your current pump, there is not any reason to go with a larger one. Hope that helps and Stay Tuned!

[@mayk3lll]

Funny how he mentions the pickup.. well if he changed oil pump sizes and on track days he is still dropping pressure then he needs to look elsewhere like he suggested and I was going to suggest pickup

[@Jan-zf8mv]

Hi, what would be the accaptable oil pressure for 2006 Subaru STI? I am currently seeing 17 - 18 psi on a warmed up engine on idle (800 rpm). This is running 10w60 oil. Is that not too low? The oil pump is still stock but the engine was rebuilt.

[@FlatironsTuning]

Given that you are running a 60 weight I would say that the hot idle pressure does seem a little low. When the engine was rebuilt, were loser tolerances used? Is that hot idle pressure what you have always seen? Or is it now lower than what it used to be? What peak pressure are you seeing when driving?

[@Jan-zf8mv]

@@FlatironsTuning most probably loser tolerances were used - I honestly have little information about what is inside the engine exactly, it was a weird situation that would need a lot of explaining. Anyway, the pressure was the same since the rebuilt. When driving pressure is at around 85 - 90 psi at 3000 - 4000 rpm. There are also no external leaks but the engine takes some oil (not too much to be worried and there is no blue smoke). Thanks for the response :)

[@FlatironsTuning]

@@Jan-zf8mv Your peak pressures sound good. How many miles since the re-build? If loser tolerances were used on the bearings, then you would need a larger volume pump to maintain pressure. If you have a descent amount of miles, then it may not be an issue.

[@playingisgame]

Who else thought the train was going to crash into the building? 😁

[@writerjmd]

Is he using the word "tolerances" to mean bearing clearance?

[@fox10169]

Is his gc actually an sti or is it an L or rs?

[@dcsymbols4450]

Anyone have the specs of what the oil pressure should be with an early RS LEGACY closed deck block and version 7 heads

[@cbarajas52]

Low pressure at warm idle, please help!!!

[@FlatironsTuning]

That is a tricky one. I'd recommend reaching out to us through Live Chat on our site (www.flatironstuning.com) and we'll see if we can sort anything out.

[@dcsymbols4450]

I think wrc engines require 12mm pump. He said he used the 10mm.. also no, the spring tension remains the same in the relief valve, you just change the rate at which it opens, As the spring never changed its physical structure.

[@jamesedmondson7265]

This was very interesting untill you mentioned you went with a thicker oil with the bigger pump. That's thrown all your testing out the window. A thicker oil with the 10mm pump would increase the pressure

[@chacelarsen50]

Clearance-amount of space between two objects Tolerance-amount of allowed variance from specified geometry Please know the difference.

[@stove08]

If I have to sit thru another double add that will be the last time I support this channel. Is one not enough!?

[@ChiefCabioch]

Crank driven pumps are a bad idea, at high RPM they can cavitate, and putting air into the oil is a death sentence for bearings, oil pumps need slowed to half crank speed which is why serious race engines run dry sump systems, some driven off cams like sprint cars, others belt driven like NASCAR and IMSA , and Drag race engines.