Accusump question - oil pressure
03-12-2010, 08:40 PM
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Accusump question - oil pressure I have a 240sx with a LS6/T56 swap. I have some work done (heads, cam, valvetrain, injectors, ported oil pump, intake, etc). I use a GTO pan, and I plan on doing some autocross, and drag racing this season.
I am looking into the accusump with electronic switch, and my question is what oil pressure switch would your suggest to use. Options are 20 discharge / 25 fill, then 35/40, and 50/55.
It a street driven toy that see's some track time, so if you have a suggestion please let me know.
I am looking into the accusump with electronic switch, and my question is what oil pressure switch would your suggest to use. Options are 20 discharge / 25 fill, then 35/40, and 50/55.
It a street driven toy that see's some track time, so if you have a suggestion please let me know.
03-12-2010, 09:51 PM
#2
I would probably go with the 35/40. I have one with a manual valve. My reasoning is that I do not want the engine pumping oil into the accusump on startup I want oil going to bearings. I suppose you can turn off the electronic valve. Once my pressure is up I open the valve gradually so the pressure stays up partially. Then close it when I am shutting the car down for a longer period of time.
03-13-2010, 03:02 AM
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The canton electric valves are passive in the fill direction, meaning even when the valve is de-energized oil may still enter the accusump.
The electric valve must be hooked to an ignition-on circuit anyways, so when you shut the car off it will maintain a charge, and when you flip the ignition on to start, it will begin discharging and effectively pre-charge the engine's oil system prior to startup.
The manual valve would work fine for you (and most everybody), but if you choose to get an "epc" valve, get the one with a discharge pressure slightly lower than your hot idle oil pressure so it doesn't discharge the accusump when your engine is sitting at idle.
Whether you choose a manual valve or electric, the pre-charge pressure will need to be set, and checked regularly. 15psi pre-charge in the air side should work for you - this will ensure a more efficient usage of the accusump's volume, and also prevent oil from entering an empty accusump until the engine oil pressure rises above the pre-charge (15psi).
You must also check your engine's oil level with the accusump holding a full charge. Hold your engine at an elevated rpm until the accusump pressure stabilizes, then close the valve (close manual valve, kill ignition for electric), and proceed to set pan level to full.
The electric valve must be hooked to an ignition-on circuit anyways, so when you shut the car off it will maintain a charge, and when you flip the ignition on to start, it will begin discharging and effectively pre-charge the engine's oil system prior to startup.
The manual valve would work fine for you (and most everybody), but if you choose to get an "epc" valve, get the one with a discharge pressure slightly lower than your hot idle oil pressure so it doesn't discharge the accusump when your engine is sitting at idle.
Whether you choose a manual valve or electric, the pre-charge pressure will need to be set, and checked regularly. 15psi pre-charge in the air side should work for you - this will ensure a more efficient usage of the accusump's volume, and also prevent oil from entering an empty accusump until the engine oil pressure rises above the pre-charge (15psi).
You must also check your engine's oil level with the accusump holding a full charge. Hold your engine at an elevated rpm until the accusump pressure stabilizes, then close the valve (close manual valve, kill ignition for electric), and proceed to set pan level to full.
03-13-2010, 08:50 AM
#4
I got the 20/25 switch based on a lengthy discussion with the folks at Canton Racing. With the 20/25 set up the Accusump really only comes into play when: (a) the ignition is turned on but the motor is not started - pre-oiling; or (b) when the oil pressure is below normal levels.
With the other choices, on the street, the Accusump is coming in and out of the picture during normal flucuations of oil pressure experienced between idle at WOT.
With the other choices, on the street, the Accusump is coming in and out of the picture during normal flucuations of oil pressure experienced between idle at WOT.
03-13-2010, 03:02 PM
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That's what I was thinking. I do need to do more homework on the manual valve. I think you set the airside to your ideal low pressure. Then on start up you open the valve, oil the motor start it up, let it fill then it only discharges if the oil drops below the pressure on the airside?
Is the 3qt the ideal unit? Because I am running out of room in there.
Is the 3qt the ideal unit? Because I am running out of room in there.
03-13-2010, 03:23 PM
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The deal with the epc valve is it effectively regulates the pressure at the switching pressure, which means that even when the accusump is holding a 60psi charge, the discharge pressure will never exceed the 20psi switch. When the oil supply fails and the accusump is called in to fill the dip, the valve will open and raise the pressure to 20psi, then shut off, wait for the pressure to fall back, then switch back on, cycling on/off around the switch pressure until supply is restored. This may not be of any major concern, so long as the engine has looser (than stock) bearing clearances that pass sufficient flow at lower pressures for adequate bearing cooling, but I suspect stock short-blocks with their tighter bearing clearances would be better served with the manual valve which will maintain higher discharge pressures when the engine needs it most.
In 240s I generally put the accusump behind the seats or under the dash if there's room. Run -10 line and it'll be fine running some distance away from the motor.
In 240s I generally put the accusump behind the seats or under the dash if there's room. Run -10 line and it'll be fine running some distance away from the motor.
03-13-2010, 03:52 PM
#7
The deal with the epc valve is it effectively regulates the pressure at the switching pressure, which means that even when the accusump is holding a 60psi charge, the discharge pressure will never exceed the 20psi switch. When the oil supply fails and the accusump is called in to fill the dip, the valve will open and raise the pressure to 20psi, then shut off, wait for the pressure to fall back, then switch back on, cycling on/off around the switch pressure until supply is restored. This may not be of any major concern, so long as the engine has looser (than stock) bearing clearances that pass sufficient flow at lower pressures for adequate bearing cooling, but I suspect stock short-blocks with their tighter bearing clearances would be better served with the manual valve which will maintain higher discharge pressures when the engine needs it most.
In 240s I generally put the accusump behind the seats or under the dash if there's room. Run -10 line and it'll be fine running some distance away from the motor.
In 240s I generally put the accusump behind the seats or under the dash if there's room. Run -10 line and it'll be fine running some distance away from the motor.
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03-13-2010, 04:02 PM
#8
That's what I was thinking. I do need to do more homework on the manual valve. I think you set the airside to your ideal low pressure. Then on start up you open the valve, oil the motor start it up, let it fill then it only discharges if the oil drops below the pressure on the airside?
Is the 3qt the ideal unit? Because I am running out of room in there.
Is the 3qt the ideal unit? Because I am running out of room in there.
03-13-2010, 04:09 PM
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I think I am going to use a 3qt unit with a manual remote operated valve. I all ready run a 25 row cooler and remote filter, so plumbing it in should be pretty easy, there is no room under the hood for the 3 qt unit, unless I can hide it under the bumper support.
03-14-2010, 04:17 AM
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I cannot say with absolute certainty that you are wrong, but your description is not how Canton explained it to me. My understanding is that if the Accusump is holding 60 psi when the 20 psi threshold triggers the Accusump opens and "responds" with the entire 60psi reserve and will remain open until it sees 20 psi downstream. Thus, the valve selection does not actually effect the degree or magnitude of the Accusump response.
This isn't a hypothetical discussion, I speak from first-hand experience in using the accusump and epc valve in multiple cars - 2 ls1 240sx's even.
Also, if you are running a remote filter adapter, double check that you're plumbing the accusump on the filtered side of the system - the accusump's floating piston seals don't like debris.
03-14-2010, 04:30 AM
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I use a Moroso bypass block -10 to a remote filter, out of the filter into a 25 row cooler, and then back to the moroso block. So I was looking into installing a check valve and a tee after the oil cooler back to the "IN" in the block.
I am going to take some measurement later today, to make sure I have some room for the 3qt system. I am still on the fence on the electric VS manual valving. But I am certain this is a good insurance policy.
I am going to take some measurement later today, to make sure I have some room for the 3qt system. I am still on the fence on the electric VS manual valving. But I am certain this is a good insurance policy.
03-14-2010, 07:36 AM
#12
A simple test will verify what I've described - charge the accusump with adequate pressure (>45psi), then shut the car off, turn ignition back on without starting motor, and observe the oil pressure. You will hear the epc valve chattering (on/off/on/off. . .) and the pressure in your guage will read approximately the switch pressure until the accusump discharges to below that pressure. How can the switch "see" 20psi downstream if the accusump is maintaining the engine's oil system at 60psi? It can't. I don't know how the canton tech described the system's operation to you, but you should realize there's no way for the pressure switch to "see" two different oil pressures at the same time. The operation really is this simple - the valve opens at <20, accusump discharges into motor, pressure rises >20, valve closes, and the cycle repeats until the oil system pressure STAYS over 20psi on it's own.
This isn't a hypothetical discussion, I speak from first-hand experience in using the accusump and epc valve in multiple cars - 2 ls1 240sx's even.
Also, if you are running a remote filter adapter, double check that you're plumbing the accusump on the filtered side of the system - the accusump's floating piston seals don't like debris.
This isn't a hypothetical discussion, I speak from first-hand experience in using the accusump and epc valve in multiple cars - 2 ls1 240sx's even.
Also, if you are running a remote filter adapter, double check that you're plumbing the accusump on the filtered side of the system - the accusump's floating piston seals don't like debris.
I am saying that if the Accusump is pressurized at 60 psi and the oil pressure drops to zero that the pressure will seek equilibrium on both sides of the now open valve. I am also saying that the valve will not restrict the pressure coming out of the Accusump unless and until pressure of at least the 20 psi at the valve is restored.
IF I am right about that part, an Accusump holding 60 psi can respond more quickly than an Accusump holding 45 psi to the same low pressure event. What do you think?
03-14-2010, 07:24 PM
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Well the critical difference between the manual and epc valves is the response characteristics for sure. Say you're at 6k and 60psi and the pump pickup grabs a gulp of air. With the epc valve, oil pressure drops to ~20psi until the supply is restored, whereas the manual valve will maintain the oil system at 60psi, slowly tapering off as the accusump drains. If that's the way you're thinking of it then you're right, although I don't think one responds more "quickly" than the other since the pressure is never allowed to drop to 0 in either case.
I've used both with no issues or failures, but the epc valve does add a point of failure worth considering - if it's power or ground were to fail, the accusump would cease function. Another thing to keep in mind when you're choosing a valve is the pressure requirements of the engine. Engine bearings are cooled by the oil passing through them, so bearings with larger clearances pass more oil and stay cooler at lower oil pressures. It follows that stock short-blocks with tight factory clearances need higher oil pressures to keep the bearings cool, and so those engines may not fair as well with a low-pressure epc valve as they would with a manual valve. Sure you could use the 45psi epc valve to kick up the discharge pressure, but then it would behave like a manual valve at idle and lower rpms anyways when the pressure is lower than the switch. That said, I've used the 20psi epc valve with no issues on a friend's ls1 240 track car for 4 years.
I've used both with no issues or failures, but the epc valve does add a point of failure worth considering - if it's power or ground were to fail, the accusump would cease function. Another thing to keep in mind when you're choosing a valve is the pressure requirements of the engine. Engine bearings are cooled by the oil passing through them, so bearings with larger clearances pass more oil and stay cooler at lower oil pressures. It follows that stock short-blocks with tight factory clearances need higher oil pressures to keep the bearings cool, and so those engines may not fair as well with a low-pressure epc valve as they would with a manual valve. Sure you could use the 45psi epc valve to kick up the discharge pressure, but then it would behave like a manual valve at idle and lower rpms anyways when the pressure is lower than the switch. That said, I've used the 20psi epc valve with no issues on a friend's ls1 240 track car for 4 years.
03-14-2010, 07:35 PM
#15
Well the critical difference between the manual and epc valves is the response characteristics for sure. Say you're at 6k and 60psi and the pump pickup grabs a gulp of air. With the epc valve, oil pressure drops to ~20psi until the supply is restored, whereas the manual valve will maintain the oil system at 60psi, slowly tapering off as the accusump drains. If that's the way you're thinking of it then you're right, although I don't think one responds more "quickly" than the other since the pressure is never allowed to drop to 0 in either case.
I've used both with no issues or failures, but the epc valve does add a point of failure worth considering - if it's power or ground were to fail, the accusump would cease function. Another thing to keep in mind when you're choosing a valve is the pressure requirements of the engine. Engine bearings are cooled by the oil passing through them, so bearings with larger clearances pass more oil and stay cooler at lower oil pressures. It follows that stock short-blocks with tight factory clearances need higher oil pressures to keep the bearings cool, and so those engines may not fair as well with a low-pressure epc valve as they would with a manual valve. Sure you could use the 45psi epc valve to kick up the discharge pressure, but then it would behave like a manual valve at idle and lower rpms anyways when the pressure is lower than the switch. That said, I've used the 20psi epc valve with no issues on a friend's ls1 240 track car for 4 years.
I've used both with no issues or failures, but the epc valve does add a point of failure worth considering - if it's power or ground were to fail, the accusump would cease function. Another thing to keep in mind when you're choosing a valve is the pressure requirements of the engine. Engine bearings are cooled by the oil passing through them, so bearings with larger clearances pass more oil and stay cooler at lower oil pressures. It follows that stock short-blocks with tight factory clearances need higher oil pressures to keep the bearings cool, and so those engines may not fair as well with a low-pressure epc valve as they would with a manual valve. Sure you could use the 45psi epc valve to kick up the discharge pressure, but then it would behave like a manual valve at idle and lower rpms anyways when the pressure is lower than the switch. That said, I've used the 20psi epc valve with no issues on a friend's ls1 240 track car for 4 years.
03-14-2010, 07:42 PM
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60psi is refering to the oil system pressure at higher-rpms.
I typically precharge the accusump to 15psi, this sets the lowest charging pressure of the system. Remember the engine's oil system will never exceed the accusump pressure, even with the epc valve since the valve is passive in fill. So a pre-charge of 7psi would have the engine seeing only 7psi of oil pressure at startup or initial cracking of the manual valve whenever the accusump is empty, slowly rising as the accusump fills and builds pressure which can take a significant amount of time. At 15 psi pre-charge, an empty accusump doesn't begin to fill until pressure reaches that minimum pressure.
I typically precharge the accusump to 15psi, this sets the lowest charging pressure of the system. Remember the engine's oil system will never exceed the accusump pressure, even with the epc valve since the valve is passive in fill. So a pre-charge of 7psi would have the engine seeing only 7psi of oil pressure at startup or initial cracking of the manual valve whenever the accusump is empty, slowly rising as the accusump fills and builds pressure which can take a significant amount of time. At 15 psi pre-charge, an empty accusump doesn't begin to fill until pressure reaches that minimum pressure.
06-01-2010, 08:47 PM
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DRZ,
I've got the 3QT Accusump with the EPC Valve and the 35-40 psi sender. LS2 with a baffeled pan. On left hand turns, I get pressure drops but it seems the accusump keeps the pressure level at 20 psi before the engine fully recovers to 30 psi+.
20 psi I'm not comfortable with given GMs spec is 6 psi/1000 rpm and I'm usually at 5000 rpm plus when the drop happens. What do I need to change on my setup to maintain 30 psi or better pressure?
John
E36 LS2
I've got the 3QT Accusump with the EPC Valve and the 35-40 psi sender. LS2 with a baffeled pan. On left hand turns, I get pressure drops but it seems the accusump keeps the pressure level at 20 psi before the engine fully recovers to 30 psi+.
20 psi I'm not comfortable with given GMs spec is 6 psi/1000 rpm and I'm usually at 5000 rpm plus when the drop happens. What do I need to change on my setup to maintain 30 psi or better pressure?
John
E36 LS2
06-01-2010, 09:08 PM
#19
DRZ,
I've got the 3QT Accusump with the EPC Valve and the 35-40 psi sender. LS2 with a baffeled pan. On left hand turns, I get pressure drops but it seems the accusump keeps the pressure level at 20 psi before the engine fully recovers to 30 psi+.
20 psi I'm not comfortable with given GMs spec is 6 psi/1000 rpm and I'm usually at 5000 rpm plus when the drop happens. What do I need to change on my setup to maintain 30 psi or better pressure?
John
E36 LS2
I've got the 3QT Accusump with the EPC Valve and the 35-40 psi sender. LS2 with a baffeled pan. On left hand turns, I get pressure drops but it seems the accusump keeps the pressure level at 20 psi before the engine fully recovers to 30 psi+.
20 psi I'm not comfortable with given GMs spec is 6 psi/1000 rpm and I'm usually at 5000 rpm plus when the drop happens. What do I need to change on my setup to maintain 30 psi or better pressure?
John
E36 LS2
Another option would be to install the manual valve instead of the EPC. With the manual valve the Accusump responds (to a presssure drop) at the full stored pressure level as opposed to that allowed by the valve.
You should be sure that the current setup is properly installed and that the oil line is sized adequately for the distance between the Accusump and the engine. Larger lines allow the Accusump to respond more quickly, all else being equal.
Last edited by Darkman; 06-01-2010 at 09:38 PM. Reason: Additional info.
