<VV> Auxiliary oil pressure systems - Accusump

[Sethracer at aol.com]

Bob - I have used the Accusump system. The "accumulator" concept is simple. 
 It addresses two problems. First, at start-up, pressurized oil is released 
into  the engine while cranking for starting. This pre-pressurizes the 
bearings which  have been draining oil out since the engine last stopped. This 
should minimize  bearing wear on startup because the first firing pulses are 
cushioned at  the rod and main bearings. When engine oil pressure comes up 
from the engine's  oil pump, a certain amount of oil is fed back into the 
accumulator to be  ready for the next startup. Before shutdown, a valve is 
closed to retain the oil  and the pressure for the next start-up. On most race 
cars, a manual  valve is used, and the opening and closing of that valve is a 
part of the  regular start-up and shutdown procedure. Electric valves are 
also available.  They can be set to open at ignition on - starting the flow - 
and close with  ignition off, saving the oil/pressure in the unit. The 
second problem it address  - Probably isn't applicable to the Ultravan. Under 
heavy cornering, the engine  oil pick-up in the crankcase can be uncovered as 
the oil climbs up the side of  the sump. Oil pressure will drop as the oil 
pump tries to pump air into the  system, because that is all it has available 
at the pick-up. If the Accusump is  open to the system, and correctly 
plumbed, when the oil pump output  pressure drops below the pressure in the 
Accusump, the oil will flow out of the  Accusump, closing a check valve, and 
supplying pressurized oil to the  engine, in theory, saving the bearings. When 
the oil returns to the pump  pick-up, pressure out of the pump will pop the 
check valve open and engine oil  will again feed the motor. 
 
My analysis. The mechanical valve units are safe and reliable. The electric 
 units have some quirks. The manufacturers admit this. The electric valve 
must  limit the refill rate at which the oil is pumped into the Accusump. 
Otherwise,  it might starve the bearings in the motor while refilling the unit. 
That doesn't  matter for start-up protection, but it does matter for 
performance use in  cornering. If the pressure is drained in a unit during a 
twisting/turning  autocross, you might not have enough time to re-pressurize the 
system until it  is needed again in more turns. This happened to me in a 
Prepared Class car on  slicks when I first installed the electric switch unit. 
I was videotaping my run  and later I could see the oil pressure gauge in 
the dash go to zero through  the last few turns. The light came on as well. It 
didn't just flicker, either. I  shut down the motor and we pushed the car 
back to the trailer. I switched  to a manual valve, and I haven't seen the 
problem. The manual valve is a pain to  deal with, but better than going 
through the motor. Canton products sells the  Accusump and they have diagrams on 
the best way to plumb it into a system. I  have never installed one on a 
street car. It is relatively simple to install one  on a racing Corvair, 
because the front-mounted coolers/filters allow easy access  to the plumbing 
lines. Not so much on a car without an external cooler. Check it  at: 
http://www.accusump.com/
 
Finally, Accusump is only one of the manufacturers. There are other  
companies that build similar units. They might be more "tuned-in" for the street  
car application
 
Good luck -  Seth Emerson
 
 
 
In a message dated 5/17/2015 9:47:32 A.M. Pacific Daylight Time,  
virtualvairs at corvair.org writes:

Hi,

Does anybody out there have any experience with any of  the "pre-lube" oil
systems I have seen  advertised?

Regards,

Bob