FA20 oiling problems, study and solution

[churchx]

Originally Posted by ETM_Shaman

..The thing with just spinning it faster is that you're not producing good torque high in the RPMs...

I don't see drawback in that. Even that lesser a bit torque is more due lower gearing multiplication then more engine torque at lower rpms when upshifted, when it comes to actual torque at wheels. Also wider usable rpm range may mean less time lost at some specific track configurations, where otherwise one may loose time for short upshift and then immediate downshift prior turn .. or loose time not shifting but also not accelerating due lower redline cutoff. And, and .. i simply love how high-rpm race engines sound

[solidsnake11]

I have a question iirc everything I read said that the wear would be on the high side of the pump, it is where the bubbles implode and wear the metal. If that is correct, your pumps erosion is on the low side. It would seem that it is building pressure on the low side before it goes into the gears. I would guess this is from squeezing oil into the gears at high speed. The little scallop on the high is to slow the pressure rise of the oil as it transitions from low to high pressure this reduces the implosion of cavatation.
Maybe the ramp on the inlet of the gear is not a great idea at high velocities. I remember reading about engineers trying to break the sound barrier and right before the engine would stall. It was discovered that the funnel to the jet turbine needed to be inverted because so much air got crammed in that the air would stall.

[solidsnake11]

Could you name the anaerobic sealant you used on the oil pump plates? Thanks

[Irace86.2.0]

Originally Posted by ETM_Shaman

The thing with just spinning it faster is that you're not producing good torque high in the RPMs. This COMPLETELY changes with head work (already done) and a good set of camshafts (one of my planned improvements). We'll have to wait for enough people to build their engines with this mods and explore to start seeing if our engine ends up being a nice high RPM screamer (n/a or boosted) like we all want to see

Having peak torque at redline doesn't really matter. If torque is falling off, it may still be better to have more revs and to shift at redline:

[ame]https://www.youtube.com/watch?v=zZBqb0ZJSwU[/ame]

[Irace86.2.0]

So what you have found is that the inlet is inadequate because sustained rpms leads to a drop in inlet pressure, and that leads to cavitation, right?

A few points of confusion:

--Shouldn't cavitation lead to a more significant drop in outlet pressure if that is the cause of the oil starvation, and you showed only a small difference in outlet pressures?

--If cavitation is happening then couldn't that metal debris be a cause of bearing failure? Moreover, shouldn't it show up in an engine oil test as metal in the oil?

--If this is the cause of oil starvation then couldn't this be replicated on a dyno or something, meaning, if it is just sustained rpms, and not sustained lateral g's or something else commonly related to track oil starvation, then couldn't it be replicated in a static environment? Is it common for oil starvation failure to happen, for instance, during a top speed run (ie long sustained rpms)?

[ETM_Shaman]

Originally Posted by solidsnake11

Could you name the anaerobic sealant you used on the oil pump plates? Thanks

We use Permatex 51813 / Loctite 518 in all applications that have machined surfaces and less than 0.5 mm gap to seal. Great product, doesn´t leave any solid residue that can clog anything.

[ETM_Shaman]

Originally Posted by Irace86.2.0

Having peak torque at redline doesn't really matter. If torque is falling off, it may still be better to have more revs and to shift at redline:

Yeah, I don´t see why anyone would want an engine that has peak torque at redline, makes no sense.
By "good torque" in my previous post I meant "enough torque to make more power than in the next gear", maybe I should´ve explained it better.
That of course is for straight line acceleration and doesn´t apply to the situation that churchx mentions (specially in low gears) where a higher redline can save you from having to make additional gear changes.
And yes, there´s also that urge to just rev the crap out of your engine, no matter the torque or power hahaha

[why?]

Originally Posted by Irace86.2.0

So what you have found is that the inlet is inadequate because sustained rpms leads to a drop in inlet pressure, and that leads to cavitation, right?

A few points of confusion:

--Shouldn't cavitation lead to a more significant drop in outlet pressure if that is the cause of the oil starvation, and you showed only a small difference in outlet pressures?

--If cavitation is happening then couldn't that metal debris be a cause of bearing failure? Moreover, shouldn't it show up in an engine oil test as metal in the oil?

--If this is the cause of oil starvation then couldn't this be replicated on a dyno or something, meaning, if it is just sustained rpms, and not sustained lateral g's or something else commonly related to track oil starvation, then couldn't it be replicated in a static environment? Is it common for oil starvation failure to happen, for instance, during a top speed run (ie long sustained rpms)?

it is one of the multiple reasons our engines are not good at high rpm's. This is awesome work and maybe just modifying the oil pickup will help a lot of people.

[ETM_Shaman]

Originally Posted by solidsnake11

I have a question iirc everything I read said that the wear would be on the high side of the pump, it is where the bubbles implode and wear the metal. If that is correct, your pumps erosion is on the low side. It would seem that it is building pressure on the low side before it goes into the gears. I would guess this is from squeezing oil into the gears at high speed. The little scallop on the high is to slow the pressure rise of the oil as it transitions from low to high pressure this reduces the implosion of cavatation.
Maybe the ramp on the inlet of the gear is not a great idea at high velocities. I remember reading about engineers trying to break the sound barrier and right before the engine would stall. It was discovered that the funnel to the jet turbine needed to be inverted because so much air got crammed in that the air would stall.

No. cavitation ALWAYS happens in the low pressure parts, actually the part with the lowest pressure is where it starts. It´s the low pressure that makes the disolved gasses convert into real bubbles. As soon as the pressure increases a little, the bubbles implode and cause the metal erosion (this is still in the pump´s inlet).

What it does in the high side is kill mass flow and cause huge pressure oscillations:

(again taken directly from the research cited and linked in my first post)


THAT is what destroys your bearings by oil starvation.

[ETM_Shaman]

Originally Posted by Irace86.2.0

So what you have found is that the inlet is inadequate because sustained rpms leads to a drop in inlet pressure, and that leads to cavitation, right?

A few points of confusion:

--Shouldn't cavitation lead to a more significant drop in outlet pressure if that is the cause of the oil starvation, and you showed only a small difference in outlet pressures?

--If cavitation is happening then couldn't that metal debris be a cause of bearing failure? Moreover, shouldn't it show up in an engine oil test as metal in the oil?

--If this is the cause of oil starvation then couldn't this be replicated on a dyno or something, meaning, if it is just sustained rpms, and not sustained lateral g's or something else commonly related to track oil starvation, then couldn't it be replicated in a static environment? Is it common for oil starvation failure to happen, for instance, during a top speed run (ie long sustained rpms)?

1. Yes I also expected to see a bigger increase in outlet pressure, it´s still a little mistery to me.

2. The ammount of aluminum it erodes is insignificant (probably less than 1.0 g). I don´t think it would show in an UOA or cause any damage. The importance of finding it is that it´s hard evidence that cavitation is happening. I´d love to see a close up pic of that part of a brand new oil pump.

3. Yes absolutely. My bearing failures where never at the track with high lateral g´s like to think about that. They happened accelerating in a straight line, at high RPMs. It could´ve happened at the dyno, I just wasn´t there.

[solidsnake11]

Well let me rephrase, the erosion from cavatation happens on the high side along with the heating of the fluid.

[Calum]

If someone with a mostly stock engine (boosted but stock internally) wanted to try a better pickup tube, would you recommend they look for something with a one inch OD as well, or would killer b's tube be the correct choice?


Absolutely fantastic research. Thank you so much for sharing!!

[Irace86.2.0]

You mentioned it somewhat, but is it possible the 10w40 oil is also the problem?


I am running 5w30 for the simple reason that Subaru runs 5w30 in all their FI applications, and I am boosted, but I could imagine running 10w40 or 10w50 on the track. With that said, I think I would drive the car for 10-15 minutes at low speeds/rpms to get the oil to operating temperature, with the concern of starving the bearings running the high viscosity oil.


There seems to be a debate these days whether higher viscosity helps to protect the bearings with a thicker layer of oil, or if it is bad. The argument is that pressures will be higher, which is good, but if oil flow rate is slowed then oil temps can creep up; thinner oil will flow faster, so it will deliver cool oil faster. Total system oil temps may not raise because the oil cooling measures post cooling could be adequate, but locally to any one part of the engine there could be a spike. Thick oil could also cause back pressure, creating resistance against restricted flow, which could be why outlet pressure is static in your chart after increasing inlet pressure.


Also, you mentioned thinner oil having less problems with cavitation. Why is this the case? Intuitively, it seems like warmer oil and thinner oil would result in more bubbles.

[NoHaveMSG]

Originally Posted by Irace86.2.0

So what you have found is that the inlet is inadequate because sustained rpms leads to a drop in inlet pressure, and that leads to cavitation, right?

A few points of confusion:

--Shouldn't cavitation lead to a more significant drop in outlet pressure if that is the cause of the oil starvation, and you showed only a small difference in outlet pressures?

--If cavitation is happening then couldn't that metal debris be a cause of bearing failure? Moreover, shouldn't it show up in an engine oil test as metal in the oil?

--If this is the cause of oil starvation then couldn't this be replicated on a dyno or something, meaning, if it is just sustained rpms, and not sustained lateral g's or something else commonly related to track oil starvation, then couldn't it be replicated in a static environment? Is it common for oil starvation failure to happen, for instance, during a top speed run (ie long sustained rpms)?

This is the same conclusion solidsnake11 came to in the other thread.