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Accusump Oil Accumulators - how do they work?

Accusump Oil Accumulators

What is an Accusump?

Accusump is an oil accumulator designed for fast road and race cars that do not want to or cannot have a dry sump system fitted. Accusump is manufactured by Canton Racing in the USA and is the original oil accumulator. In basic terms, it is a reservoir that stores oil at pressure, ready to release oil before the engine is started or when the oil pressure drops in use, preventing internal engine damage due to oil starvation. 


How does an Accusump work?

The Accusump is designed to collect pressurised oil in normal engine running. It then stores this pressure, ready to release at a later stage when the oil pressure in the engine drops. It contains a piston valve which is preloaded with air on one side of the valve which moves the piston valve down the reservoir and pushing the oil into the oil system when required. The piston valve is then moved back up the reservoir by the engine oil pressure in normal running. The amount of air pressure is relative to the amount of engine oil pressure normally required. The air pressure can be adjusted by using a hand pump on the Schrader valve at the gauge end of the reservoir body. The oil stored under pressure can then be used in two ways;

  • To pre-lube the engine on next start up, preventing damage to the engine internals due to wear. When the engine is shut off, the Accusump valve closes and any oil pressure in the reservoir is held there until the engine is next started. At this point the Accusump will then release oil into the engine and then you can start the engine.
  • To prevent engine damage due to oil starvation where the oil pump cannot pick up oil from the sump. The reservoir is pressurised by the engines oil pressure in normal running. It is also preloaded with air and when the pressure in the oil system drops, the Accusump will sense this and release the stored oil back into the engine, preventing engine damage. 



What size options are there?

The Accusumps are available in three sizes. These are sized, confusingly, in Pints. We believe this is done by the UK importers, where as Canton actually size them in US Quarts.

  • 2 Pint (1 US Fl.Quart) which is about 946ml. The body measures 3.25” (83mm) in diameter x 12” (305mm) body length. This size is suitable for small engines or for use as an engine pre-lube.
  • 4 Pint (2 US Fl.Quart) which is about 1.9 litres. The body measures 4.25” (108mm) in diameter x 12” (305mm) body length. This size is suitable for medium 4-6 cylinder engines.
  • 6 Pint (3 US Fl.Quart) which is about 2.83 litres. The body measures 4.25” (108mm) in diameter x 16” (406mm) body length. This size is suitable for large 8 cylinder upwards engines.

If you need further, more in depth help with choosing which Accusump is correct for your application, see this helpful document:

Click here to see the Accusump Selection Guide - by Canton Racing Products


Valve Options

Canton manufacture three different valves for use with the Accusump. The manual lever valve, the standard electric valve and the EPC valve.

The manual lever valve is for use in race only cars where the valve can easily be accessed by the driver. This is usually fitted directly into the reservoir body or can be remote mounted in the hose running to the Accusump. It must be opened before starting the engine and closed before the engine is shut off. This is the simplest, easiest and cheapest valve option. 


The standard electric valve is for use in road cars or vehicles where it is difficult or just not convenient to have the manual valve. This electric valve is designed to slowly refill after oil release and is ideal for road cars because of this. This valve can be turned on and off by a toggle switch on the dash or by wiring straight into the ignition switch. For full on racing cars which require a rapid refill of oil, we would recommend using the EPC valve kits, below.


Visually similar to the standard electric valve, the EPC (Electric Pressure Control) valve is designed for racing applications where a rapid refill of the reservoir is needed. The valve stays in the off position during times of normal oil pressure. With it in this position it is able to quickly recharge the Accusump with oil pressure after discharge, ready for the next oil surge. As you can imagine, this is vitally important in racing conditions where corners come up quickly and frequently. If the oil pressure drops below the EPC pre-set level, the valve opens and releases the stored oil pressure into the system. These valves are available in pre-set pressure ranges 20-25psi, 35-40psi and 55-60psi. Like the standard valve, they can be wired to a toggle switch on the dash or directly to the ignition switch.


Plumbing Options

There are a few different ways in which you can plumb the Accusump into your oil system. The Accusump can be mounted anywhere convenient, in racing cars this is usually in the passenger seat area which is easily accessible by the driver. We have seen them mounted in various other locations including the boot area and even under the bonnet. Remember that if you are considering mounting it a good distance from the engine, the valve will need to be mounted somewhere closer to the engine so that there is no delay in the Accusump releasing pressure to the engine. The valve can be remote mounted from the reservoir, in a place more convenient to the driver. We also sell suitable mounting clamps, remote cables for the valve and we can supply all pipe work and fittings required to install the Accusump.

1:  The easiest method is to connect the Accusump directly into the oil gallery of your engine. This will be the most effective and require the least amount of fittings to do so. However, not all engines have a big enough port in the engine to be able to do this, so we recommend that you speak to your engine builder about machining one when the engine is stripped. We would recommend something like ½” NPT, ½” BSP, ¾” UNF or larger port for doing this.


2:  If you do not have a port big enough to be able to do the above method, there is now a special Mocal sandwich plate available which has a one way valve fitted inside it. The sandwich plate fits between the engine block and the oil filter. One port of the plate is blocked off. This is another easy solution to plumbing the Accusump into your engine. The one way valve prevents the oil draining through the oil pump and returning to the sump. However, the one way valve can be restrictive and if you already have a sandwich plate fitted for an oil cooler, you will not be able to use this method. If you do have an oil cooler fitted, see option 3.


3:  A really easy way to plumb in your Accusump, if you have an oil cooler fitted, is to tee into the return oil cooler hose. You will need to use the Accusump one way valve to prevent the oil flowing the wrong way and pressurising the oil cooler. We sell t-pieces which the one way valve can be screwed directly on to. You then just require a hose coming off this t-piece up to the Accusump. Note, the oil will have passed through all the other components (remote filter head (if fitted), oil filter, oil thermostat (if fitted) and oil cooler) before reaching the Accusump.


Note: When using an Accusump for pre-lubricating, an oil filter with an anti-drain valve (most filters have one) will prevent oil flowing back to the sump via the oil pump.

Click here to see all our Accusump System Fittings

Click here to see Full Fitting Instructions

If you have any questions, please do not hesitate to contact us for help and advice.

Archived in: Accusump | Oil systems

6th August 2019