Malc
For racing purposes, you don't really need the valves, if you have a dry sump engine with a large enough sump to contain the extra 2/3 quarts of
oil. With a wet sump and a 3-quart Accusump, it is a little more iffy, as you might over-fill the wet sump. Let me explain.
When the
oil pressure drops, the
oil will flow from the non-check-valve Accusump tank to buffer the oil pressure, flowing up to the depletion of the Accusump volume of 2/3 quarts. After that, well, it depends on your luck and exact cause of the low pressure.
[If, like me many moons ago, your Purolator oil filter can split, remote mounted on a F/A behind the wing/dry sump tank, you will drop ALL the oil around the track until that screechy/crunching sound. That's when we "re-invented" the BIG oil light. To this day there remains a serious oil stain at Pocono!]
Since you already will have a nice supplemental oil system installed and ought to pre-oil a very expensive engine (or even a cheap one), why not put at least a single valve at the Accusump tank entrance, which can be closed just before you pit and retain the volume and pressure before you shut-down the motor? Then, just before start-up, you can open the valve and allow the oil to pre-lube. Start at will. It is a freebie protection plan.
Now, remember that your engine is not yet running, so no scavenge pumps are running and returning the oil from the engine sump to the dry sump tank or pushing it back into the Accusump tank. This means, subject to your particular engine's drain-down channels and features, you are placing the Accusumps 2/3 quarts into the engine oil pan and the oil level is raising somewhat higher than normal, depending on the exact geometry of the sump pan. Start-up will subject the engine internals to considerable splashing at some unknown force levels, caused by the higher engine sump (oil pan) oil level. Therefore, avoid big revs until the oil returns to the Accusump tank after start-up. How long? Perhaps only a few minutes in hot weather and 15 or more in late fall early morning New England.
Some race engines just don't want to start very easily and don't even like to idle at all below 1500 when just a little cool, let alone cold. So, it is a trade-off, but worth the risk IMHO. i have not heard of anyone suffering a failure traced to the excess hydrodynamic forces generated by an excess oil level [except for radial aircraft engines, another whole story for later]; although many of us have over-filled one way or another and pumped/splashed excess oil out of an engine via the dipstick/breather/etc with nothing but embarrassment and a messy engine compartment to show for it.
The valve on the Accusump can be manual, perhaps necessitating the system to be mounted on the floor of the passenger area, or at least an extra line or two installed to bring the valve near your reach.
But, the valve can also be electric operating, with a 12V DC solenoid and a securely covered switch mounted on the panel or nearby. This is handy and allows a very remote placement for the Accusump, which does contain flammable oil. i like the mechanical valve, personally. There are lots of wiring/plumbing variations to suit your own ideas of safety, security and service.
There is little doubt that the system works as designed and works very well. i've never lost an engine that had one, including most of the street cars, which also have long had fire systems. i could not imagine an engine worth over $5K that wouldn't need one, though my street Trailblazer and wifey's Honda CR-V are not currently so equipped.