Quote:
Originally Posted by AndyW
- Accumulator has a 7-10# bladder pressure..the air pressure that will vacate all the oil. For this to happen, system pressure would have to go to essentially zero. So full discharge is not realistic in an operating (vice prelube) scenario.
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sounds correct
Quote:
Originally Posted by AndyW
- The control valve will always let system pressure push oil into the accumulator as long as system pressure is above the EPC valve setpoint. It functions as a check valve when the EPC is below it's setpoint. So oil will fill the accumulator to 90# (basically max out put pressure) and somewhere between 2 and 3 quarts.
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yes, I usually see mine sitting at around 120psi. cold starts produce lots of pressure. Also, 1st and 2nd gear the oil control isn't as good since the acceleration is so fast. You can sometimes see over 100psi oil pressure in 2nd gear. Normal pressure under full load is ~80psi or so.
Quote:
Originally Posted by AndyW
- When pressure falls below the EPC setpoint, the EPC allows flow toward the system and flow rate will be based on the D/P. So, if the setpoint is 60#, that is a 20# D/P initially, with a reducing flow rate as D/P goes down due to the Accusump piston moving due to the D/P. Assuming system pressure continued to head toward 40# the Accusump will keep emptying until it equalizes with the system with some remaining volume in the tank (the only way the tank empties if if system pressure gets to 7-10#, which would be "Game over" while moving).
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yes pretty much.
Quote:
Originally Posted by AndyW
This leads me to believe the earlier the oil starts flowing as you move toward a minimum system pressure, the better - you have more time to push oil into the system before a critical point is reached (lets pick 40# as the red line since that is around idle pressure, as that seems to be the concensus). If we picked the 35-40# EPC valve, the initial pressure between the tank and the system is greater when the valve opens, so the flow rate will be higher than if you were using the 55-60# EPC valve, but the discharge for the 35-40# EPC is much closer to danger when it starts helping. I need to see if Canton has any flow rate vs D/P graphs. It may be moot. All of my events are less than 4 seconds. i.e. If the Accusump discharges from 80# to 40# in 2 sec and 80#-60# in 3 seconds, I think it's a wash.
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Yeah that's getting more into it than I bothered. I emptied it out into a bucket once and with no pressure in the lines it only took a split second to empty. 3qts oil volume isn't much when spinning at high rpm. If you have some sort of line pressure the accumulator can help supplement you at the set-point for several seconds though. That's all I really needed to know lol. Mostly concerned with keeping the line pressure up for those 2-3 seconds moments where n54 and n55 vehicles seem to experience a drop in a oil pressure for whatever reason.
I could log oil pressure at 3,000rpm/60psi and once the light flights on to show it's dumping I can see how long the oil pressure stays up above say 50psi. Then do the same test again with no accusump. I posted a few autocross logs where you can see 25psi lows bumped up to 40-50psi lows with the Accusump and that was enough data for me lol.
How quickly it discharges is really going to be relative to how much volume the accumulator is being asked to make up for.