accusump question

[Belgian1979]

Has anyone here ever run an accusump without the check valve so the oil cannot flow back to the pump when the accusump discharges ? Canton says it's needed. Not sure however if the oil would be able to get pas the oil pump gear. I do think that it might end up fighting the oil pump.

thanks

[66Vette]

Belgian:

I believe it depends on how you have the system plumbed. If you are using their sandwich adapter for a spin on filter, they do not use a check valve. Their concern is if you have things plumbed to a remote cooler or filter, you could dump the charge into them or the plumbing. Here's what they say about the one way valve:

"Check Valve ensures all the oil being discharged out of an Accusump goes to lubricate the engine bearings and is not fed back toward the pump. For use in systems where a remote oil filter or a cooler is used. Uses 1/2" N.P.T. female threads."

Here's the installation instructions:

http://www.accusump.com/accusump.pdf/instructions.pdf

Regards, Cris

[lorax]

Like 66 Vette said, it depends on how the system is plumbed. In my case I do not use a check because the remote fiter is the closest thing to the accumultor and with a anti drain back the oil won't go the filter backwards anyway. The oil really doesn't want to backflow thru a spining oil pump either. But if you have a cooler and lines, then the filter, oil will fill those devices first in they aren't full. If the filter doesn't have a anti drain back valve, it adds to the problem.

If you are thinking that the check can cause a oil pressure drop, it can, and it is just one thing you have to consider in your plumbing. In my estimation, the checks supplied by Canton, if thats where you got it, are too restrictive for my tastes to flow the full suply of oil the engine needs, as installed in their plumbing diagram.

[cash canada]

I ran the system with a check valve for years with no problems. From my memory of your plumbing drawings in earlier posts, my system is plumbed differently than yours.

In speaking with some fellow racers, they said to remove the check valve because it is a flow restriction and the accusump will never back feed a spinning oil pump. They are well respected and work for a major cup team so I have taken there advice and removed the check valve. At least there are 4 less potential leak points in the plumbing now. And upon closer examination of the check valve it is a significant flow restriction.

I have not run the engine yet, but did prime the oil system to fill the a sump oil lines cooler filter etc. I opened the sump to see if it would feed the engine . It did. As I watched the oil pressure gauge go up, I also noticed that the oil pump was turning backwards as I could see the drill spinning backward as it was still attached to the primer tool. No the drill was not turned on and the pump was not connected to the cam shaft either.

So I can say that without the check valve the oil will flow to oil the block and back through the lines until if the oil pump is allowed to rotate backwards. This would not happen in a running engine. I can also say that the accusump would still prime the engine without the check valve installed for start ups even with the oil pump being allowed to rotate in reverse, which would not happen if the distributer were installed.

I think you are safe with or without it installed.

[Belgian1979]

I should explain this a little further. I had oil pressure dropping at higher rpm. Took some time to do the test but finally was able to. After taking out my oil cooler and everything in between the filter and the pump and connecting the engine directly to and from the filter, the test pointed out that it is a restriction in the circuit in between the filter and the pump. Only a couple of things as far as I can see can be responsible for this : oil cooler or the accusump one-way valve. A next set of tests will determine what exactly it is.
Personally I think it's the oil cooler (B&M hi tek, stacked plate) as the behavior it exhibits points in that direction, meaning that I do not have a pressure drop when oil temps are below oil thermostat closing and bypassing the cooler and I do have oil pressure dropping as soon as the oil thermostat opens to the cooler at 100%.

As for the plumbing : the car doesn't have a lot of room left to put the accusump. I had to tuck it in under the front bumper brackets, which makes for some pretty extensive lines and plumbing. There is no way around that in this car.

I have the filter as the last thing before it enters the block. There was some debate were to put it (first or last). I put in the last location since you're never sure that even a new oil cooler/accusump has some dirt in it that will work loose over time.

In essence there is no restriction for the oil to flow back to the oil cooler or the pump.

Short of running no check valve the only thing to do is either disconnect the accusump entirely (which I do not like to do) or use a larger check valve, like a -12 (lines are -10) of a flapper type...not sure if this is a good option with oil though.

If I'm right and the oil cooler is the restriction, well that's another story. I have been looking over oil coolers but the ones that are big enough to be no restriction are to darn big to fit up front (hood bents inward and almost touches this cooler). I was thinking about making a bypass of sorts before the cooler with a valve that opens when the pressure falls off at the exit side of the cooler to prevent the pressure from dropping. In that way the cooler would still partly perform it's function but it would prevent the pressure drop to an extent.

Opinions are welcome on this.

[lorax]

.
Personally I think it's the oil cooler (B&M hi tek, stacked plate) as the behavior it exhibits points in that direction, meaning that I do not have a pressure drop when oil

DING DING DING

Unless that stack plate is pretty large, I would bet that is the problem. Headered tube coolers flow much better for the physical size. The stack plate exchangers do a great job of cooling the oil, and are very efficient, but they need to be pretty large to flow enough oil.
I would not totally discount the check, but I have more confidence in it than the cooler.

I am glad to see that you know understand the any restriction is the system between the pump out and the engine oil inlet will trigger you pump relief and cause a drop in the block oil pressure. Its not the pump, its the restriction between the pump and the block.

BTW, even after you find the problem, it is not unusual to have to raise the relief pressure in the pump to account for the increased flow resistance of well designed cooler plumbing. No matter how well you plumb the system, it will put up some resistance to flow, and the pumps relief will see that and open before you see the reliefs PSI rating in the gage.

[Belgian1979]

You mean tube fin type coolers are better for flow ?

The strange thing about this pressure drop is that it only makes itself seen as the rpm's go up. Looks as if it's not restricting below a certain gpm of flow but after a certain level it is.

[Kevin Johnson]

On Monday, August 5th, 2013 you tested your system and the temperature high that day at the Brussels airport was 29 C (84 degrees F). I think you ran your most recent tests this past week with a temperature high of about 9 C (48 degrees F). Your car was hit and went in for repair at the end of August 2013.

I think it would be a good idea to be cautious in your conclusions and might even be a good idea to wait until it warms up a bit more in Belgium as, as you mentioned a number of times in the past, the temperature of the oil was associated with the oil pressure problem. You have removed several confounds from the system but I do not think you have a temperature gauge for your oil (??) and so are guessing right now.

Good luck with your experiments.

[Belgian1979]

Kevin,

True that it's a guess. But this is an educated guess. Oil pressure at idle when driven for a long time to get the engine up to operating temp gives about the same idle pressure (35-40) as during summer. If the oil is colder or the car is not thoroughly driven until warm the oil pressure at idle stays around 70-80 psi.

[lorax]

You mean tube fin type coolers are better for flow ?

The strange thing about this pressure drop is that it only makes itself seen as the rpm's go up. Looks as if it's not restricting below a certain gpm of flow but after a certain level it is.

You think that might be because at lower RPM it isn't moving as much oil thru the system. Resistance goes up the more you try to flow. It can all be sized perfectly, for a small 4 cylinder. I think you understand that you need a larger fuel line, filter, etc for a dominator on a BBC than you do a 2bbl on V6, not just a bigger pump.

Oil is no different. If it can ge

[lorax]

You mean tube fin type coolers are better for flow ?

The strange thing about this pressure drop is that it only makes itself seen as the rpm's go up. Looks as if it's not restricting below a certain gpm of flow but after a certain level it is.

You think that might be because at lower RPM it isn't moving as much oil thru the system. Resistance goes up the more you try to flow. It can all be sized perfectly, for a small 4 cylinder. I think you understand that you need a larger fuel line, filter, etc for a dominator on a BBC than you do a 2bbl on V6, not just a bigger pump.

Oil is no different. If it can't get thru all the lines, filters and coolers, the pressure in the block will drop.
Don't take you eye of the thermostat either!!!!
All these things might work fineseperate. Add all the pressure drops combined, and they add up to one larger drop. 2lbs here, 2lbs there, next thing you know, you're down 15lbs.

[Chris1]

Kevin,

True that it's a guess. But this is an educated guess. Oil pressure at idle when driven for a long time to get the engine up to operating temp gives about the same idle pressure (35-40) as during summer. If the oil is colder or the car is not thoroughly driven until warm the oil pressure at idle stays around 70-80 psi.

Oil temps in a jacketed engine - such as yours - are driven primarily by coolant temps, much less so by intake air and ambient conditions, or even operating conditions - within reason of course. So... as long as your thermostat is operating correctly, operational oil temp won't be 'that much different' on a summer day versus winter - assuming engine is thoroughly warmed up. Line size < #10 will typically demonstrate the pressure loss you described with increased rpm, even in short well radiused/etc distances. To me it appears you've proven the issue to yourself - now just insure your mods improve the flow in your external lines. Sounds like you're doing a good deal of external routing. Gdlk!

[Kevin Johnson]

When around 180°F (thermostat opening) she idles around 35 psi (in neutral). When at rpm of above 5000 she doesn't seem to drop of noticably. Only time I saw it drop was when going over a bump, which I didn't see before. Could be that the accusump was kicking in at that same bump in the past.
When hot, overal pressure was also higher at 75 psi. I seem to loose around 10 psi in the lines to and from the ancilliaries.

If the Accusump discharged because of low oil pressure and the bump caused aeration in the oil and pressure drop then the air release rate and low residency time of oil in the sump would mean that the Accusump was recharged with aerated oil with a lower bulk density. Therefore a percentage of the original charge volume of neat oil in the Accusump would then be present in the sump proper. If this series of events was repeated then the problem would increase.

For the same reason of lowered bulk density and air release rate, the sump could now be effectively over filled with oil and affected by the rotating assembly. As oil is struck by the rotating assembly it heats up and this increases the bubble size and further decreases the bulk density (a vicious cycle though damped by the faster air release rate of larger bubbles in warmer oil).

With the proper fill level, surface foaming from a temporary bump and surface strike by the rotating assembly would typically be knocked down by the anti-foam surfactant. Without the permanent added volume from the Accusump discharge the volume change from entrained aeration could still be low enough to keep the oil surface away from the rotating assembly.

It is important to consider all the data. Be cautious in drawing conclusions. It is fortunate that you are consistent in your motoring route and noticed the pressure drop at the bump and lack thereof in different circumstances.

Oil temperatures from oil windage issues could be significantly higher than coolant temperatures.

[Bob Hollinshead]

.
Personally I think it's the oil cooler (B&M hi tek, stacked plate) as the behavior it exhibits points in that direction, meaning that I do not have a pressure drop when oil

DING DING DING

Unless that stack plate is pretty large, I would bet that is the problem. Headered tube coolers flow much better for the physical size. The stack plate exchangers do a great job of cooling the oil, and are very efficient, but they need to be pretty large to flow enough oil.
I would not totally discount the check, but I have more confidence in it than the cooler.

I am glad to see that you know understand the any restriction is the system between the pump out and the engine oil inlet will trigger you pump relief and cause a drop in the block oil pressure. Its not the pump, its the restriction between the pump and the block.

BTW, even after you find the problem, it is not unusual to have to raise the relief pressure in the pump to account for the increased flow resistance of well designed cooler plumbing. No matter how well you plumb the system, it will put up some resistance to flow, and the pumps relief will see that and open before you see the reliefs PSI rating in the gage.

I've seen stacked plate style transmission coolers cause a restriction.

[Belgian1979]

When around 180°F (thermostat opening) she idles around 35 psi (in neutral). When at rpm of above 5000 she doesn't seem to drop of noticably. Only time I saw it drop was when going over a bump, which I didn't see before. Could be that the accusump was kicking in at that same bump in the past.
When hot, overal pressure was also higher at 75 psi. I seem to loose around 10 psi in the lines to and from the ancilliaries.

If the Accusump discharged because of low oil pressure and the bump caused aeration in the oil and pressure drop then the air release rate and low residency time of oil in the sump would mean that the Accusump was recharged with aerated oil with a lower bulk density. Therefore a percentage of the original charge volume of neat oil in the Accusump would then be present in the sump proper. If this series of events was repeated then the problem would increase.

For the same reason of lowered bulk density and air release rate, the sump could now be effectively over filled with oil and affected by the rotating assembly. As oil is struck by the rotating assembly it heats up and this increases the bubble size and further decreases the bulk density (a vicious cycle though damped by the faster air release rate of larger bubbles in warmer oil).

With the proper fill level, surface foaming from a temporary bump and surface strike by the rotating assembly would typically be knocked down by the anti-foam surfactant. Without the permanent added volume from the Accusump discharge the volume change from entrained aeration could still be low enough to keep the oil surface away from the rotating assembly.

It is important to consider all the data. Be cautious in drawing conclusions. It is fortunate that you are consistent in your motoring route and noticed the pressure drop at the bump and lack thereof in different circumstances.

Oil temperatures from oil windage issues could be significantly higher than coolant temperatures.

Kevin,

I also did the tests with normal oil level and 1 qrt less in the pan. No difference. Of course the accusump is not in play at the moment and for the next series of tests when I reconnect the lines to the cooler it will stay disconnected (not able to discharge) untill I'm certain which is causing the drop in pressure.