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Thread: GTM Accusump thread

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    Senior Member beeman's Avatar
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    GTM Accusump thread

    I'm strongly considering an Accusump for my LS3. I thought it would be beneficial for current and future builders to have information about this system in one place.
    I think the main topics would be (let me know if there are any other topics to consider)
    Let me know what else to add, I'll try to update this post.

    Accusump tank - size, location, orientation
    -1,2,3 quart - go big. Per manual, the Accusump will provide 15-60 seconds of pressurized oil depending on engine variables/RPM. I'm guessing this is the 3 quart unit.
    -per manual: The Accusump™ will work with the tube in any position or orientation; however, if possible, mount the tube with the oil end (the end with the oil valve) slightly higher than the air end. This will prevent accumulation of air bubbles (coming from foam in the oil) by purging any minor air pocket during pre-oiling, when it will not cause any harm.
    -watch for heat sources, in general heat necessarily won't hurt it, but unilateral heat, such as from a header, can distort the Accusump tube and cause binding of the piston, therefore failure.

    Accumulator pre-charge - psi, ?leaking gauge?
    The precharge does a couple things- makes sure that the oil is discharged from the Accusump when there is no pressure on the oil side of the piston, and prevents the entire accumulator from filling up with pressurized oil (i.e. a BOMB!). There is a pressure relief valve on the oil side of the accumulator that purges (at 175psi !!!! per manual) oil to avoid catastrophic failure. If you read enough about the Accusump, you will hear stories of the Accusump 'puking' oil all over the engine bay or wherever it is mounted. This is probably due to no air pressure on the other side of the piston (ie no precharge).
    One issue that I have come across (and is mentioned in the manual) is minute air leakage around the air pressure gauge fitting on the accusump (or even possibly air leaking within the gauge itself -- very hard to detect!) that causes a gradual drop in precharge pressure, ultimately causing the Accusump to 'puke oil' all over the place. Moral of this story - watch your precharge pressure. At least one person ditched the Accusump precharge air pressure gauge and replaced it with a schrader valve on some air hose that he mounted in a convenient location that he could get a tire pressure gauge on to check his precharge.

    Per manual: With the valve in the open position (electric units energized) and the engine not running; pressurize the Accusump™ (air fitting) to 60 psi. This will ensure all the oil is out of the unit and the piston is all the way to the oil end. While the Accusump™ is pressurized to 60 psi check all the fittings (gauges and lines) for leaks. Apply soapy water to each area and check for bubbles. If possible, wait overnight to ensure there is no loss of pressure. For the unit to operate correctly there cannot be any leaks in the air side. Temperature change will affect pressure. Once you are sure there are no leaks, bleed down the air pre-charge to between 7 and 10 psi. Now when you start the engine and open or energize the valve, the pressure in the air side of the Accusump™ should increase to approximately that of your engine oil pressure.



    Plumbing - fittings, location in oil circuit, etc
    -minimum of AN-6 for 1 quart units and AN-10 for 2 & 3 quart units. BUT I believe that I read somewhere that the Accusump has NPT fittings?
    - can attach in line with external filter, cooler, etc (Canton recommend a check valve to make sure the accumulator oil flows towards the engine and not towards the cooler - some say the check valve can be a problem - too restrictive?) vs attach directly to the block/oil galley (vs sandwich between filter and block - probably not an option on the LS)
    - ideally install it post-filter, any minimal debris can foul up the piston and cause failure





    Manual vs Electric valve, and electric valve settings, wiring, indicator light?, etc



    The manual valve is more fool-proof, but is it better? One Corvette guy asked : if motor gets hot and oil pressure begins to drop, you come into a corner at 3k rpm, engine oil pressure at 30-35 and accusump (matching the engine oil pressure) pressure begins to drop with the oil pump pressure. Then in the corner the oil pickup goes dry, is there enough pressure in the accusump to keep the oil pressure up? Versus the electric valve that keeps 60 psi in the accumulator, and begins to dump it out when the engine oil pressure drops, say lower than 30 psi. I think the latter is safer.

    $227 for the kit with pressure sensor and electric valve. https://www.summitracing.com/parts/c...273x/overview/

    I love the idea of a dash indicator (bright blinking light) to know when the Accusump is dumping (engine oil pressure dropping). From Corvetteforum:






    Testing, maintenance, etc
    -lots of info in the manual
    Last edited by beeman; 12-09-2017 at 01:14 PM.
    MK3.1 2004 Mach 1 donor. ABS, PS, TC.
    GTM #304 LPE 525hp LS3
    2000 C5 Lingenfelter LS1@489hp
    1999 Corvette FRC/Z06 track car

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