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Thread: Accusumps

  1. #1
    Regular Nige's Avatar
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    Accusumps

    I`ve been having issues with low oil pressure blips, particularly since going to 17`s.

    My sump is baffled and when it`s filled to just above Max I don`t have any issues but as soon as it burns off enough to drop to halfway down the dipstick I lose oil pressure on high G left handers.

    The obvious answer is to ensure the oil is always on Full, but I want a more robust system than that.

    Accusumps seem to be the answer. I understand the basics, you pressurise them with an air pump to say 40psi, the engine fills the cylinder with oil and if the engine pressure drops below the set pressure the oil is pushed back into the engine by the pressure in the cylinder.

    It then refills itself once the engine is pumping back above 40psi.



    I`m happy to run a manual valve to isolate the Accusump when the engine is stopped to keep it full of oil.



    The issue is, I`m not sure if I have space to fit a 2nd sandwich plate to allow the oil from the accusump into the engine. If I fit a Tee into the oil cooler > engine line, I`m assuming I need to fit a one way valve in the return line to stop any oil going backwards through the filter and the pump ? Or isn`t that necessary ?

    Would a 1.5qt or 3qt be best for me ?

    Anything else I`ve missed ?

  2. #2
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    Dry sump?
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    Quote Originally Posted by sparrow View Post
    Dry sump?
    Isn`t the point of these that you don`t need one

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    Regular ste's Avatar
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    I'd say it's more of a half-way house.

  5. #5
    I still need to figure out the correct method for checking the level of my dry sump I aint touched it yet, I should.
    Ermmmmm

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    In through the engine oil pressure switch ? (Relocate switch obvs).
    Orifice can be made larger if required but I would have thought it’s ok.
    It seems it’s just to be anywhere on the pressure side.

    Dave-I’m not believing you don’t know how to check your oil.....

  7. #7
    Regular stevem's Avatar
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    Quote Originally Posted by sparrow View Post
    Dry sump?
    This.
    Simon no longer owes me anything, Dave does though.
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  8. #8
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    Quote Originally Posted by ste View Post
    I'd say it's more of a half-way house.
    Damp sump?
    "Fortunately, I'd taken a spare Gearbox, Turbo, Actuator, Banjo Connector, Steering Rack, Driveshafts, ECU, Wideband sensor, 57-51mm silicone reducing elbow and a Copper Banjo Washer." - Nige

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    Quote Originally Posted by Fitz711 View Post
    In through the engine oil pressure switch ? (Relocate switch obvs).
    Orifice can be made larger if required but I would have thought itís ok.
    Diameter is too small and can`t be enlarged

    From reading the manufacturer site, they suggest a check valve is rarely needed. The reasoning being the oil pump is still turning, the cooler is full and the filter is in the way, oil prefers the easiest route which is through the engine rather than against the flow.

    Ste, ah, interesting I suppose from a cold engine startup point of view, accusump is far better but for what I`m looking at one for the dry sump is more efficient ?

    For teh cost, i`ll be sticking with an accusump or keeping my oil filled

  10. #10
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    Accusump responds to an issue, dry sump prevents it from happening in the first place.

    If you're struggling for a pick up, can the accusump valve be controlled by the ECU? Pressure drops, ECU opens valve, pressure rises, ECU closes valve.
    I don't know how an Accusump works, so not sure if this is feasible.
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  11. #11
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    Quote Originally Posted by sparrow View Post
    Accusump responds to an issue, dry sump prevents it from happening in the first place.

    If you're struggling for a pick up, can the accusump valve be controlled by the ECU? Pressure drops, ECU opens valve, pressure rises, ECU closes valve.
    I don't know how an Accusump works, so not sure if this is feasible.
    Whilst that can be done, it`s not needed. The cylinder is pressurised and ensures the oil system is always at that pressure. Until either the pump makes the required pressure or the accusump is empty. That can last anything from 15 to 30 seconds.

    If the oil pump hasn`t started pumping again in 30 seconds I`ve probably got a hole in the sump

    Once flow is reestablished, the extra oil is pushed back into the accusump where it sits and waits until needed to maintain pressure.

    I knew nothing about them yesterday, but after a bit of reading they are very very simple bits of kit. A bore, a piston with air on one side and oil on the other.

  12. #12
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    Quote Originally Posted by Neil Mac View Post
    Damp sump?
    Mildly moist?
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    In most cases the rubber anti-drain ring in the oil filter will stop the oil going the wrong way. I'd be tempted to go remote filter if your "stack" is getting too big
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    Quote Originally Posted by Neil Mac View Post
    Damp sump?
    Quote Originally Posted by Stace View Post
    Mildly moist?
    You guys will have a field day if I said it can be used to pre lubricate...

    Here’s a brief description but I’m sure there’s a video somewhere.

    https://www.merlinmotorsport.co.uk/k...-they-work-281

    I can’t remember where but I’m thinking I’ve seen it before but there was a ‘collar’ or 8mm thick washer tigged over the oil pressure switch which then allowed fitting of a larger connector by taking out the internal diameter.
    I’m guessing there’s no blanking plugs on oil galleries but again it’s diameter that’s not ideal.

  15. #15
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    Hi Nige,

    My pal Matt at Think Auto sells Accusumps, why donít you drop him a line? Iím sure heíll advise accordingly and do you a deal if you decide to go ahead. How big an oil cooler do you have? Could you be seeing a pressure drop due to the size of cooler or take off, routing of hoses? Maybe consider a Laminova cooler if thatís the case as I understand the are more efficient.

    Matt@thinkauto.com

    Cheers,

    TC
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  16. #16
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    Gareth put one in the Elise (Acusump).

    It works and the start-up protection seems like a nice added bonus. But sadly that's all I can tell you about it

  17. #17
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    Quote Originally Posted by tallchap View Post
    Hi Nige,

    My pal Matt at Think Auto sells Accusumps, why don’t you drop him a line? I’m sure he’ll advise accordingly and do you a deal if you decide to go ahead. How big an oil cooler do you have? Could you be seeing a pressure drop due to the size of cooler or take off, routing of hoses? Maybe consider a Laminova cooler if that’s the case as I understand the are more efficient.

    Matt@thinkauto.com

    Cheers,

    TC
    The oil cooler causes very low pressure drop, less than a laminova actually. But good shout.

    It all seems to be that there is a sweet spot where the oil level is enough to never lose pressure, but when it gets to about 1/2 on the dipstick I`ll get the odd loss of oil pressure on certain corners.

    Spoke to Simon Hart yesterday, he used to have exactly the same issue but since fitting and accusump he`s never had a single low oil pressure warning, even when switching to the larger slicks.


    Thinking a 2 quart one will be fine. ?


    Good call on the one way valve in the oil filter Gareth, i`d forgotten about that. I`ll just tee into the cooler return line, that`ll be dead easy to plumb
    Last edited by Nige; 28-03-2019 at 08:25 AM.

  18. #18
    You can calculate reserve capacity fairly easily, you need to know engine speed, oil pump flow characteristics and the period of time the reserve is required.

    If you can give me the oil pump part # I'll see if I can dig up a curve for you

    Cheers

    Pete

  19. #19
    Quote Originally Posted by Fitz711 View Post
    In through the engine oil pressure switch ? (Relocate switch obvs).
    Orifice can be made larger if required but I would have thought itís ok.
    It seems itís just to be anywhere on the pressure side.

    Dave-Iím not believing you donít know how to check your oil.....
    Its notoriously hard.

    I checked at the weekend, several factors. Its supposed to be checked when the engine has just been switched off or even still running. I turned it off, **** the cap gets hot

    It looked like it had oil in , although it was clean so quite hard to check, its not like a normal dip stick, more a cocktail stick sized bit of wire . Apparently the way to make sure is add 250ml of oil and wait until it blows it into the catch tank. I added 250ml went for a quick drive and the catch tank was still empty, I'll add another 250ml and try that again.
    Ermmmmm

  20. #20
    Regular ste's Avatar
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    I made a long dipstick that reached right to the bottom of the sump so you could check when cold. The standard Caterham way of dipping that little thing into the tower before the oil drains back into the sump is asking for trouble IMO.

  21. #21
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    Quote Originally Posted by Weeman View Post
    Apparently the way to make sure is add 250ml of oil and wait until it blows it into the catch tank
    That doesn`t sound like they never considered checking the oil level until someone asked the question at all...

  22. #22
    Quote Originally Posted by Nige View Post
    That doesn`t sound like they never considered checking the oil level until someone asked the question at all...
    Pretty much
    Ermmmmm

  23. #23
    From my understanding of an Accusump it's concept is basically the same as any accumulator used in hydraulics - even if you never have "low" oil pressure it will still smooth any brief dips in pressure from the nature of the oil pump's pulses.

    Because it's just trying to maintain pressure in the oil system you can fit it anywhere on the pressure side (between outlet of oil pump and first pressure drop) with no need for a check valve etc. unless you want something clever to maintain oil pressure ready for start.

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