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Old 12-24-2017, 08:41 PM   #276
KillerBMotorsport
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If the cooling setup is done right it's typically a wash. What you loose in pressure drop, you gain back in pressure due to temperature drop. A generalization of course.

I'd bet an 11mm shimmed to 85psi would cover your needs and reduce the bypass flow in the process. Don't know anything about how your engine is built though. I just rarely rarely rarely... did I mention it's pretty rare... that a 12mm pump is required
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Old 12-25-2017, 11:18 AM   #277
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I think one of the bigger questions is how much pressure is really needed?

I know that this site long sings the old hot-rodder adage of 10 psi per 1000 RPM in power band with and operating temps.

I know on real race engines we did a lot to find the minimum needed pressure to keep an engine alive without wasting power. However I don't think most need to worry about a few hp in the name of safety. I think it's more necessary to define an acceptable lower limit that is tolerable. Of course this would depend on such a huge array of variables that it really is pretty pointless.

I have customers running over 550 lb-ft in the 3-4k RPM range and then you have the guys that are on a big turbo with the same torque value at 7k RPM. It's a very different demand for the oil wedge.

I do agree with Chris that a 12mm pump is not needed for any Subaru platform, unless your on a very loose engine, with a massive journal bearing turbo and D-AVCS. Most people neglect that that pump comes from a D-AVCS, with twin, journal bearing, turbos.

Dom, Chris and I have harped about the added heat and aeration it puts into the oil system. Heck, the only reason I slapped one onto my beater 2.1 build is because I still had the pump that started this thread, just sitting around.

It'll be running with my prototype bypass valve and de-aerator...yeah, no longer using that poor Peterson valve. Glynn, I work with getting you onto something better when it's all sorted out.
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Old 12-25-2017, 12:58 PM   #278
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Once of our test engines from 4 or so years ago ran the mid-high 50psi range. It was designed to run that way though. It lived a fine life, but in the end we ended up going a different route.

Absolutely on pressure/flow. The hard core real race teams want no more parasitic losses than are absolutely necessary.

Several years ago I played around with a few external bypass designs. One of them a multi-stage bypass that provided a more linear pressure plot. The goal being to have pressure follow RPM and provide no more pressure than necessary. You can get almost similar results playing with needle, seat, and spring pressures as well. In short, the project never went beyond testing due to lack of bang-for-the-buck. In other words, there's n reason an OEM pump can't do the job if the pump/engine are built right, 99.98% of the time.
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Old 12-26-2017, 08:32 PM   #279
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Totally agree. We spent a lot of time with oil system optimization for Cup engines and of course some on the GT but when it's a BOP series, you only push so much.
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Old 12-27-2017, 08:05 AM   #280
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Quote:
Originally Posted by Homemade WRX View Post
I think one of the bigger questions is how much pressure is really needed?...
Though I dug around quite a bit on the internet before choosing 85 PSI, I see Chris at 100 PSI in the video.
Quote:
I do agree with Chris that a 12mm pump is not needed for any Subaru platform, unless your on a very loose engine, with a massive journal bearing turbo and D-AVCS. Most people neglect that that pump comes from a D-AVCS, with twin, journal bearing, turbos.
Was that a 2.0L that had DAVCS and twin turbos? Spec C or RA? Did that engine also have squirters?
To me, this bolsters my argument about the appropriateness of a 12mm pump! The engine you're describing runs higher RPM's, probably has tighter clearances and yet is smaller displacement and AFAIK has no external oil system to cause any parasitic pressure drop. If there is any justification for moving up to 90~100 PSI then it may be more relevant to have the 12mm pump.
I also haven't decided if I will enlarge galleries prior to the main bearings or not. If I did it would make it more incumbent on the main bearing clearances and then the rod bearing clearances to be what meters the oil flow to the heads.

I'll ask this again: "I don't understand the chart that shows a 12mm pump with 1.9L more flow than a 10mm pump but yet the output pressure is equal. In fact they're all the same pressure rating of 14 PSI when at 600 RPM. I don't see how that's possible. (Given the differences in displacement)
Quote:
It'll be running with my prototype bypass valve and de-aerator...yeah, no longer using that poor Peterson valve. Glyn, I work with getting you onto something better when it's all sorted out.
Micah, I look forward to seeing what you come up with.
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Old 12-27-2017, 01:57 PM   #281
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Quote:
Originally Posted by Scargod View Post
I'll ask this again: "I don't understand the chart that shows a 12mm pump with 1.9L more flow than a 10mm pump but yet the output pressure is equal. In fact they're all the same pressure rating of 14 PSI when at 600 RPM. I don't see how that's possible. (Given the differences in displacement)
The numbers in that chart come from the service manuals. I think they would have come from some sort of a test setup or design specs and not actual measured figures in a running engine.


And yeah, I don't know exactly how much pressure is "enough" either. But we did have a car (I didn't build it) that only made 56psi at redline and didn't seem worse for wear after a few time attack events. But then the car was parked for awhile and eventually sold so I never got it apart to look at the bearings or anything. Certainly made me nervous though.
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Old 12-27-2017, 03:16 PM   #282
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Quote:
Originally Posted by Scargod View Post
Though I dug around quite a bit on the internet before choosing 85 PSI, I see Chris at 100 PSI in the video.
We were shooting for ~90psi. This was a stock 11mm pump with 1-shim, that we later removed to bring the pressure down. This was one of our early engines where we ran a super tight and tight toleranced main bore; .0007 clearance +/-.0001 or another way of looking at it is .0006-.0008 main bore clearance. This is now our 'standard' as it works exceptionally well.

Quote:
Originally Posted by Scargod View Post
Spec C or RA? Did that engine also have squirters?
Yes the JDM models. There are variances, but these engines run different fuel, displacement, turbo, etc. They do have remote oil coolers from the factory too. As I mentioned before, it's not a great comparison for us.

A larger pump does not increase flow. The passages and clearances do.

There is a pressure profile for the oil pump itself, and for the spring you use. Where they cross paths and what your engine was built for is where that pressure needs to be.
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Old 12-27-2017, 05:10 PM   #283
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Well, I would beg to play Devil's advocate.
Volume and restrictions determine pressure. Given a larger pump, you can open up passages and bearing clearances and it can still net the same pressure. Your tight tolerances are beyond most builders. You don't just shuffle bearings to do what you are talking about. Your high pressure and tight clearances may equal what many or most do with looser tolerances and a more substantial flow or "cushion of oil". That seems like what "most" (?) seem to strive for.

I don't have the experience. You do, but some of it seems hard for the average shop or person to accomplish. Especially on a budget.
I like the external oil pressure bypass valve. No teardown and no shims to fool with. I can change the oil viscosity and/or adjust the pressure almost infinitely.
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Old 12-27-2017, 08:01 PM   #284
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Quote:
Originally Posted by Scargod View Post
Well, I would beg to play Devil's advocate.
Please do as the devil is in the details

Quote:
Originally Posted by Scargod View Post
Volume and restrictions determine pressure. Given a larger pump, you can open up passages and bearing clearances and it can still net the same pressure.
You are exactly right it's a straightforward calculation when looking at the numbers you're shooting for the same P though. The point I and others are making is that you'd have to open your areas up significantly to require a NECESSARY increase in flow. In the end, if you want to run a 12mm then go for it. Just be safe about it and datalog. If you aerate out the bypass it will take very little time to cause damage, and it will likely not be gauge detectable. Similar to what can happen with an 11mm on a 10mm engine from too much pump flow capacity.

Quote:
Originally Posted by Scargod View Post
Your tight tolerances are beyond most builders. You don't just shuffle bearings to do what you are talking about. Your high pressure and tight clearances may equal what many or most do with looser tolerances and a more substantial flow or "cushion of oil". That seems like what "most" (?) seem to strive for.
Any quality motorsports type machine shop should be able to provide any main specs you provide. If you're shuffling bearings you're building a budget engine and should have budget engine expectations because you get what you pay for. Know the oil wedge calcs for how much space you need for oil to provide proper lubrication. Then know the engine, loading, component and application data.

The old adage was big clearances allow more oil flow. It does provide great flow out the mains, but the problem here is the Subaru EJ doesn't have a main bearing oiling problem. It's the rods. So while your big clearances are good for flow to the mains, it means you're bleeding out more in stead of pushing it to the rod bearings... where the loading is really abusive and good oil supply is crucially important.

So my philosophy is that my tight mains provide better flow to the rod bearings. Since going to this formula we've never had an engine with an oil related bearing failure.

Quote:
Originally Posted by Scargod View Post
I don't have the experience. You do, but some of it seems hard for the average shop or person to accomplish. Especially on a budget.
I like the external oil pressure bypass valve. No teardown and no shims to fool with. I can change the oil viscosity and/or adjust the pressure almost infinitely.
Nothing wrong with being on a budget, but you want a racecar. You know the saying; CHEAP/RELIABLE/FAST you can ONLY have two.

External bypass is handy for experimentation, but I'd like to see some marked improvement in something. Careful with making changes due to viscosity changes. If you try to always maintain the same pressure with different viscosities it will effect flow rates, potentially in a bad way if you were try and dial in 20w-60 for the same pressure you'd get from 0W-20. Don't do that
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Old 12-28-2017, 08:53 PM   #285
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Quote:
Originally Posted by KillerBMotorsport View Post
A larger pump does not increase flow. The passages and clearances do.
Only critique is that this isn't true. It will flow more oil at lower RPM's, and anywhere under the curve, that it is making more pressure than a smaller pump...for the same given engine.

Also, as you know, it is positive displacement pump, so it is always flowing more than a smaller pump, just not necessarily through the engine. It'll just be heating and aerating the oil as it pumps it through the relief.
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Old 12-29-2017, 08:32 AM   #286
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Quote:
Originally Posted by Homemade WRX View Post
Only critique is that this isn't true. It will flow more oil at lower RPM's, and anywhere under the curve, that it is making more pressure than a smaller pump...for the same given engine.
True, when you're below the regulating pressure, which gets fuzzy since regulator plungers all tend to bleed a bit differently before being compressed to the bypass port, but we're splitting hairs here.

For 99.998% of us, we care about pressure under load at RPM. In which case the pump size won't matter, with all else equal.
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Old 01-07-2018, 01:22 PM   #287
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The important thing to note is, there isn't a one size fit all for oil pumps. Some engines will need less and some need more due their setup, clearances, wear, and so on. So don't buy into, you should only run this size or that size because of blah blah blah... For example, my EJ207 has good oil pressure with the 10mm, but my EJ205 doesn't with the 10mm, but does with the 11mm. They both are seeing about the same pressure under load at RPM, even thought the oil pump size is different between them.

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