Accusump

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Damn. Just missed it.

WTF is this??

https://www.amazon.com/Canton-...ords=oil+accumulator

So, its an electric oil pump.  How does it work with the actual oil pump when engine runs??

It plumbs into the return full flow filter/cooler return line (I would imagine the closer to the engine the better) and works with your regular pump. Any time your oil pressure drops (I think it's pre-set at about 20lbs) the valve opens and keeps the pressure from falling. You wouldn't have to run a deep sump. It would be great for pre-oiling the engine before starting, and you wouldn't have to worry about freeway on/off ramps . You close the valve before shutting the engine off, open just before starting and the engine avoids most of the wear associated with turning over an engine with dry bearings. The only caveat I can see is the thing would empty itself when idling at a stop light when the engine's at operating temps, but I think 2 quarts would be enough...Al

With the electric solenoid, you don't have to manually close and open the valve.

When I shut my car off I rev the engine a little to increase the stored pressure in the Accusump.

I added a switch so I can turn the car electrical on without discharging the Accusump when I want to work on electrical stuff.

Danny P has one on his Spyder, I think.

So a 2qt accusump would put 2qts of oil into the system upon start up? How do you not end up with a motor that's 2qts too full when it barks to life? I get that once it's started it will automatically start to refill the accusump. I just don't understand how you keep from over filing the block with oil

At start up you open the valve to pressurize the oil passages, start the engine, it immediately builds oil pressure and then the Accusump 'shuts off', and refills itself. Same for losing oil pressure going around a corner; it would only be momentary or a few seconds at best. I would think a 1 quart unit would be more than adequate for pretty well everything we do.

Ps- on an engine with a deep sump you could use it as a pre-oiler and just close the valve after starting.

I have an Accusump and I have always wondered the same thing.

However, mine is a 1-quart version so if there is overfilling, it won't be by so much.

It doesn't empty instantaneously. The oil is flowing through tight spaces, like bearings. So, as soon as the engine starts oil flows back into it. The amount of emptying may be quite small.

It's for pre-oiling cars that sit a long time between starts, and for saving the engine during auto-X, hillclimb competition and other hooligan shenannigans. 

I think it makes more sense than a deep sump on a VW engine. No clearance issue and on-demand, automatic cool, clean oil. A poor man's dry-sump, if you will. 

Only downside I can see is potential complications during oil change time.

There's no downside, other than controlling the pressure the thing sees (on the high side). I've blown three Hobbs pressure-switches, so I just use it for pre-lube now.

I don't need it for anything else with the dry-sump, but if I were running wet again, I'd have one and a thin-line sump, and never worry about running dry again.

It works like a pressure bladder in a domestic water system with a single speed well-pump.

@edsnova, when I do an oil change, I turn the key without starting the car. This allows the oil in the Accusump to discharge into the sump to be drained with the other oil.

I refill the oil to the line on the dipstick and then start the car to push oil into the Accusump. Then I top off the oil again.

I now have the Accusump together with a thinline sump. I added the thinline when I went from 1776 to 2110.

Those of you (I guess it's Stan and Michael) that have experience with an Accusump- As I understand it, the Accusump is designed to dump oil back into the system when pressure drops below 20lbs; is this an issue when idling at a light with an engine at operating temps and only producing 8 or 10 psi at idle?

@ALB, it really doesn't function as you describe.

It can have either a hand-operated valve or electrically-operated valve. For our purposes, I would say the electrically-operated valve is the one to use.

When the key is turned the valve is opened and stays open until the key is off. Most of the time the pressure in the Accusump is essentially the same as the pressure in the engine. If the engine suffers a loss in pressure, the Accusump now has higher pressure and pushes oil into the engine.

The amount of oil in the Accusump varies with the pressure. Before I shut my car off I usually rev it up and then turn the key to push more oil into the Accusump.

At idle there would be more oil in the sump because less is in the Accusump under low pressure.

I get what you're saying, but I'm still unclear on something, Michael (although I'm not sure what). I had read (I thought it was in Accusump literature somewhere) that any time oil pressure in the engine dropped below 20lbs that the unit would open and start "feeding" the oil galley. How much oil would it dump in when sitting at a light for a minute or 2 with the engine idling and only making 8? 10? 12? lbs oil pressure? Would it empty itself? Be half full? 1/4 full?

Don't get me wrong; I think an Accusump is a great piece of equipment, and for the cost (especially if you've spent big $$$ on a bigger, badder engine) the idea of being able to pre-oil before starting (where most bearing wear happens) is very attractive.

I could be concerned about nothing...Al

Possibly unrelated question: without an Accupump, just plain old oil pump, full flow filter, no extra sump, if one was concerned about lack of oil on startup after along sitting, how about pulling the dizzy central tap, and just turning the engine over for a number of seconds, or a minute maybe.  With no fire in the hold, and things just spinning free, so to speak, would not the wear on bearings, etc. be minimal, and the oil would be pushed around some to get things wetted PDQ, seems to me.  Maybe not as good as an active pump running before any turning, but maybe not too bad??

You are correct, Kelly, it would certainly be easier on parts. You'd only have to turn it over a few revolutions to get pressure. It would work best if you also pulled the plugs, but that's more work.

@ALB Unless someone makes a transparent Accusump it is hard to know how much oil is in it at idle. Probably, as long as there is any oil pressure in the engine there is some oil in the Accusump. I would guess maybe 1/4 full.

The Accusump tries to match the oil pressure in the engine. If the engine pressure goes down the Accusump releases oil and when the engine pressure goes up, more oil is pushed into the Accusump.

... a LOT more work.  Not going there.  That said, I know that there are infernal combustion engines that have compression release vales in the heads to facilitate starting.  I have a chain saw like that.  A little valve sort of button thing you push down to vent some pressure, and when the engine fires, the combustion pressure slams that valve shut, and off you go.  Maybe if we had one of those on a solenoid in each cyl, and could activate it w/ a switch. and then . . .  this is getting way to complex.  Better to use the MUSBJIM approach: put gas in and drive it like you stole it, keeping an eye out for a good burger joint.  KISS, in other words.

Don't you set the 'back pressure' in the sump by pre-loading the piston with air?

As I understand an accusump it's basically a big ole pill with a piston inside it. On one side of the piston is air and a pressure gauge. On the other side of the piston is oil and a hole for the oil to escape.   The oil pressure of the engine pushes the piston and compresses the preloaded air chamber. In periods of 'low pressure' that compressed air wins and pushes oil back into the motor. How much oil it pushes depends on how much 'air' you've preloaded into the air side and your existing oil pressure being generated from the motor.  The accusump and the oil pump are always trying to achieve a balanced pressure.

Do I have that wrong?

Here's how it works:

The Accusump itself is a vessel for storing pressurized oil. There is a piston inside the vessel with a slight air charge on the end opposite the oil connection. The piston ensures that the oil chamber is always full of oil, and not a mixture of oil and air. It also ensures that when the pressure on the oil side of the piston is less than the pressure on the air side, the oil will get pushed out.

The accusump is tapped into a high-pressure oil connection, which is easy if the engine is full-flowed (just tap in on the outlet of the oil filter with a tee). With the most basic connection (a ball valve), the Accusump is either taking on or discharging oil all the time.

That's not how most people use them, however.

The best set-up has a solenoid valve (which is just an electrically opened valve). It's a special valve because it will allow oil into the Accusump whether the valve is powered or not. Unpowered, the valve acts like a check-valve-- it will allow oil into the vessel, but not out of it. When power is applied to the valve, it allows flow both in and out.

Obviously, this power is keyed with the ignition switch. But it also generally runs through a Hobbs pressure switch on the engine side of the solenoid valve. The switch makes when pressure drops below a certain set-point-- the switches are available at many different pressure points.

The effect is that whenever the key is on, there is power to one side of the switch-- but it only makes when the pressure is below the set-point (20 psi, for example). This allows the valve to open and oil to flow into the galley of the engine. The switch also has a point where it breaks (30 psi, for example), so that when the galley pressure rises to that set-point the valve closes again.

With the vessel pre-charged, and the engine off, the galley pressure is below 20 psi, so the valve opens and oil fills the galleys. As pressure in the galleys rises to 30 psi, the valve shuts off. With a properly functioning set-up on a tight engine, you can watch the pressure bounce between the make and break set-point (until you run out of oil in the Accusump), and you know the Hobbs switch is working.

Once the engine is running, the pressure jumps up enough that the Hobbs switch breaks, and the solenoid closes-- stopping flow back into the engine, but still allowing the vessel to fill with oil (because it acts like a check-valve). Oil can ALWAYS go into the vessel, but can only get out when the valve is powered. It's pretty cool.

Anyhow-- yes, when the Accusump is pre-lubing (pressurizing a non-running engine), the sump will be overfilled-- but only until it starts. Once running, the Hobbs switch breaks, and the Accusump re-fills with oil. 

Once running, if the oil pump pick-up is exposed to air for some reason (drag racing wheelstand, long sweeping turn, etc.) and the pressure drops below the Hobbs switch set-point, the Accusump will keep the galley's pressurized until it runs dry.

I've "blown" (ruptured the diaphragm inside) a few of the Hobbs pressure switches by exposing them to more pressure than they like. I have an external pressure relief that bypasses back to the sump when galley pressure exceeds 80 psi, but 80 psi every cold start is too much for the switch (apparently). Since I'm dry-sumped, I cannot really run out of oil. So the "save your engine from oil starvation" feature isn't really needed.  I just jumped the switch, and run through a switch on the dash.

My order of operation is:

1) I turn on the key with the Accusump switch off and allow my carb float bowls to fill

2) I flip the Accusump switch on and watch my oil pressure gauge until it comes up

3) I crank to start

4) Once running, I shut the switch off.

The Accusump then refills as I drive down the road, and is pressurized to whatever my highest oil pressure was for that drive, ready for the next start-up.

It works. It's simple. There's a lot of confusion surrounding it. It's not 100% foolproof (the piston has o-rings, and can be susceptible to contamination), but I don't think I'd have an overpriced engine without one.

Stan The Man from Stanistan: a wonderful, and very patient, discussion.  For me, this is a "Who knew?" sort of thing, and so now I do.  Txs.

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