Oil Accumulator

[DarkPira7e]

Originally Posted by NoHaveMSG

Well I have a 2 qt on the way. I'll source the valve and hose separately. Not sure why I haven't gone this route before, I had looked into it before but don't know why I didn't follow through.

I am so thankful I don't go to tracks and my worries are extremely simple comparatively Props to all of you for fighting hard

[KillerBMotorsport]

Originally Posted by NoHaveMSG

Well I have a 2 qt on the way. I'll source the valve and hose separately. Not sure why I haven't gone this route before, I had looked into it before but don't know why I didn't follow through.

If you're willing and able to do some pressure/volume testing shoot me a PM, and I can walk you through a couple of different methods to do that.

[NoHaveMSG]

Originally Posted by KillerBMotorsport

If you're willing and able to do some pressure/volume testing shoot me a PM, and I can walk you through a couple of different methods to do that.

When I get to that point I will let you know. Engine still has to come out of the car before this season starts

[NoHaveMSG]

@blsfrs

To the oil galley, are you using an 18x1.5 to -10an adaptor or something else? Like a 18 x 1.5 to 1/2npt then to -10


edit:Nvm found a -10 adaptor straight to the oil galley. Still curious what you are running though.

[blsfrs]

Originally Posted by NoHaveMSG

@blsfrs

To the oil galley, are you using an 18x1.5 to -10an adaptor or something else? Like a 18 x 1.5 to 1/2npt then to -10


edit:Nvm found a -10 adaptor straight to the oil galley. Still curious what you are running though.

The first option: 18x1.5 to 10an adaptor. Don't ask me where I got it 'cause that was 3 years ago and I can hardly remember what I had for breakfast.

[NoHaveMSG]

Originally Posted by blsfrs

The first option: 18x1.5 to 10an adaptor. Don't ask me where I got it 'cause that was 3 years ago and I can hardly remember what I had for breakfast.

lol

Thanks. That is exactly what I got on order. Have all the hose and fittings on the way.

Thinking about just buying something like this to operate it. It is a solid core wire so it works in push/pull, and it's like 100 cheaper then Canton's manual cable kit.

https://www.amazon.com/Dorman-55198-..._t3_B0BC87YL8R

[blsfrs]

That cable basically is the same one that I have. I ran mine through the "sound hole" just below the HVAC.

FWIW: If you mount your accusump in the same location as mine, it has to be far enough forward so it sits between the bars so the bottom of it should be flush with the bottom of braces. If it sits on top of them, it contacts the hood.

[pope]

Originally Posted by blsfrs

P1V1=P2V2 anyone? Oh Boyle!!!

So, if I’m doing this right:

7*1.5=90*x
X=0.1166667

1.5-0.1166667=1.3833333

Then, when the air side is charged at 7psi and compressed to 90psi, by filling the oil side, the air chamber will reduced from 1.5qt to 0.1166667qt leaving 1.3833333qt of volume for the oil side.

[NoHaveMSG]

Originally Posted by blsfrs

That cable basically is the same one that I have. I ran mine through the "sound hole" just below the HVAC.

FWIW: If you mount your accusump in the same location as mine, it has to be far enough forward so it sits between the bars so the bottom of it should be flush with the bottom of braces. If it sits on top of them, it contacts the hood.

That is good to know. I was checking out some options that are not going to work and am thinking about mounting it vertically.

[blsfrs]

Originally Posted by pope

So, if I’m doing this right:

7*1.5=90*x
X=0.1166667

1.5-0.1166667=1.3833333

Then, when the air side is charged at 7psi and compressed to 90psi, by filling the oil side, the air chamber will reduced from 1.5qt to 0.1166667qt leaving 1.3833333qt of volume for the oil side.

I just got off the phone with Canton, their 2qt accumulator actually holds 2 quarts not 1.5. So 7x64/90=5oz of air volume and 59oz oil. I'm a licensed medical professional, so somebody needs to check my math.

[KillerBMotorsport]

Originally Posted by pope

So, if I’m doing this right:

7*1.5=90*x
X=0.1166667

1.5-0.1166667=1.3833333

Then, when the air side is charged at 7psi and compressed to 90psi, by filling the oil side, the air chamber will reduced from 1.5qt to 0.1166667qt leaving 1.3833333qt of volume for the oil side.

Keep in mind this is a static formula for that snapshot in time. With the unit run as an accumulator (dampener/open), it's constantly being supplied different pressure, based on RPM, AVCS, etc... plus flow rate is going to be based on the pressure differential, which is almost always going to be 7psi, unless there is an instant and dramatic loss in oil pressure.

The right way to do this is plot out the full travel and flow rate based on a specific condition, like instant pressure reduction from say 60psi to 40psi over say a 3 second period.

When RPMs are naturally varying as you are going through the gears, downshifting, AVCS, etc., the oil level in the accumulator is going to be constantly changing. Again, this can be plotted out so if you know in gear 4 at 5,000 RPMs if your pressure instantly goes from 50psi to 20psi and stays there for 5 seconds you can find the flow rate over those 5 seconds back into the system.

None of these scenarios come anywhere near dumping 1.5 quarts, and you're not charging with 90psi, because at temp pressures are never that high. Once you start looking at these flow rates, you see this is not going to prevent an engine from popping. Maybe it keeps it from popping today, or tomorrow, but it's not fixing a problem (if one exists). For anyone that wants to nerd out on this and actually plot it out, ideal maximum flow rate is going to be around 8 quarts/min (1.33 Quarts/10 seconds) for a Suby 12mm Gerotor pump. I don't know how close this is to actual, but is based on other Subaru engines of similar design, same gerotor pump size, and D-AVCS like the FA20/24. Should be a safe starting point.

Another wild card to add into the mix that no one ever thinks about is air in the system. If the pump or bypass is cavitating (providing an instant loss in pressure) your accumulator is going to be splitting duties between adding oil that is going out bearing clearances, and compressing the air that is now in the oiling system. Same deal if the pickup starves. Again, real world conditions are HIGHLY dynamic.

I stick by my opinion for now that accumulators are not a good application for these engines, or any Subaru engines. It's a dampener (when used open) on an engine that doesn't need one. It's more cost, complexity, potential leak points, and weight (worse, weight that's up high).

If anyone wants to put the time, effort, and risk in to proving me wrong, I'm game, and will gladly eat my words and humbly beg for the forum's forgiveness. We have the dyno and every bit of testing equipment to make it happen. Better yet, have Phil from Element post real data. He loves debating me, and we're way overdue

[Ultramaroon]

The system is incomplete. For an accumulator to do any good there must be some hysteresis, like an easily opened check valve to fill and in parallel, a dump valve that flops open below a set pressure delta.

[NoHaveMSG]

Originally Posted by Ultramaroon

The system is incomplete. For an accumulator to do any good there must be some hysteresis, like an easily opened check valve to fill and in parallel, a dump valve that flops open below a set pressure delta.

I have been looking at adding a secondary dump for a couple days. I just hadn't decided where it would go.

I am not under any type of delusion that this is a fix. I consider it more a set of suspenders as I have already get dropouts into single digits and this year I will be on more tire and aero. I have to do something at this point.

[pope]

Originally Posted by Ultramaroon

The system is incomplete. For an accumulator to do any good there must be some hysteresis, like an easily opened check valve to fill and in parallel, a dump valve that flops open below a set pressure delta.

I think this is where an electric valve and a controller would be beneficial rather than a manual valve or pressure switch.

The electric valves are only closed in one direction when off enabling it to fill and hold until switched on by the user or a pressure switch, unlike the the manual valve which must be opened to fill and/or empty.

Tying an electric valve into either a standalone or arduino (etc) and say comparing oil pressure vs rpm vs accumulator charge pressure to determine when to open the valve would give the benefit of fast reaction like a simple pressure switch, but without dumping oil every time pressure drops because rpm did.