I would like to add an accusump type device to our LeMons car.
Anybody have any ideas on how to make one at home? Are there any "kits" on the interwebs?
I tried searching, but all I found were used accusumps which were still $$$.
I don't mind paying for the real deal and supporting the company, it would just be cheaty as hell on a LeMons car.
Thanks,
Rob
Several bmw's used hydraulic pressure accumulators as part of their suspension and or brake systems, they're all pretty small but you could string a few together. I have no idea if they would tolerate the temperature and composition of engine oil.
Two that spring to mind:
don;t some classic saab 900s also use hydraulic boosted brakes with a small electric pump to pressurise them?
This is what comes to mind. 1. Old style air/ water fire extinguisher that is pressurized through a schraeder valve. 2. A cheap cigarette lighter air compressor 3. oil lines as needed.
Why do I have these thoughts?
Don't think "accusump" and the associated internal piston. Think "oil accumulator", which is just a tube that's capped at each end. Fire extinguisher would work fine, but I'll bet you could make something out of pipe. You don't need constant pressurization, you just need to do the initial pressurization so there's no need for a compressor. Then you use a ball valve to cut off the accumulator before shutting down the engine, thus retaining the pressure built by your engine.
I would like it to "automatically" put oil into the system if the oil pump does not pick up any oil.
Basically, if I starve the pump of oil due to cornering, it would provide enough oil for the engine to survive.
I am thinking about using an oil bilstein shock. I saw somewhere that a shrader valve can be welded onto the end where the nitrogen pressurization normally is. There is a floating piston in the bore that seperates the oil and nitrogen. I could then weld a fitting on the other end after taking the shock shaft out of the bore.
I think this would work.
Any suggestions?
Thanks,
Rob
Can you extend and baffle the oil pan, like a road race pan?
wvumtnbkr wrote: I would like it to "automatically" put oil into the system if the oil pump does not pick up any oil. Basically, if I starve the pump of oil due to cornering, it would provide enough oil for the engine to survive.
Yes, that's what they're for.
A shock isn't going to have enough internal volume.
Basically, they're quite simple. An accumulator is a reservoir of oil with some air space. Under normal operation, the air in the accumulator is pressurized to the oil pressure of the engine. This is done by the oil pressure in the engine.
If the oil pressure drops, the pressurized air will push pressurized oil into the oil system. This will continue until the air pressure matches the oil pressure of the engine, which is why you need some volume to your accumulator. Once the oil pressure picks up again, the oil pump will refill the accumulator until the pressures match.
Before you shut off the car, you close the ball valve on the oil line to the accumulator. This seals it off and traps the pressure inside the accumulator. Otherwise it'll dump out all the oil when you turn off the engine and the oil pressure drops to 0.
If you want to pre-oil your car, you open the valve on the accumulator just before you start the engine - you've only got a second or two before it empties. Otherwise, you open it once oil pressure has been established.
The purpose of the piston is to keep the oil and air separated. It also allows the unit to be mounted in any orientation. But it can stick, and if it does then the accumulator doesn't work. A simpler and cheaper method is to simply use a tall accumulator with the oil fitting at the bottom.
Having done a few accusumps I've found that the accusump needs to be right near the bearings to work right. These ones that mount in the foot well really dont do a whole lot as by the time the oil drops at the pump the bearings are already "dry", the few milliseconds later when the accusump compensates its too late.
I'm sure they take a little of the edge off, but they really need to be plumbed right to be effective. They are good though, pre oiling the engine, added oil capacity, etc
If it were me, I'd pull the oil pan & make a scraper / baffle / trap door setup so the pump never runs dry.
KJ
Keith wrote: Don't think "accusump" and the associated internal piston. Think "oil accumulator", which is just a tube that's capped at each end. Fire extinguisher would work fine, but I'll bet you could make something out of pipe. You don't need constant pressurization, you just need to do the initial pressurization so there's no need for a compressor. Then you use a ball valve to cut off the accumulator before shutting down the engine, thus retaining the pressure built by your engine.
All parts available at your local Home Depot.
Now, asking for it to automatically pressurize you oil system when it reads low, that's a different kettle of fish. Now you're talking home-made dry sump system to maintain oil pressure regardless of what the engine's doing, and there was a thread about that a couple of months or so ago....
The shock idea: don't think so. The volume of oil in a shock is tiny compared to what an engine needs--even in a just a couple of seconds low oil pressure situation.
Want to make your own? Here's a rough recipe.
You need a reservoir. A fire extinguisher is a good idea, but anything that can take your cold oil pressure will do. Accusumps (TM) are a simple tube with ends that screw on. The nice thing about this is that you can completely disassemble them for cleaning. Capacity should be 2-4 quarts or so, and you want it tall instead of wide.
Okay, you have your reservoir from somewhere. At the bottom end, put in a big fat fitting for your oil line. Attach a ball valve to this. Now run a line from the ball valve to however you're hooking the accumulator up to the engine.
At the top of the reservoir, install a schrader valve and an optional pressure gauge. Mount the reservoir in the car vertically.
Voila. Not difficult or expensive.
Moroso recommends overfilling the sump by 1.5 qts or so on a 2.5 qt accumulator, then starting the engine. This lets the oil pump fill the accumulator for you. They use the valve to blow out old oil when doing an oil change.
triumph5 wrote: Now, asking for it to automatically pressurize you oil system when it reads low, that's a different kettle of fish. Now you're talking home-made dry sump system to maintain oil pressure regardless of what the engine's doing, and there was a thread about that a couple of months or so ago....
Nope, not at all. The pressurization automatically happens because you have 1) a big pressurized reservoir and 2) an attached system with less pressure. It's really not complicated. Physics says the oil will go from the high pressure to the low. It's not going to hold for a long time, but it's not intended to replace the oil pump completely, merely step in when you have a momentary problem.
Why do some of the accumulators have the internal piston? I figured that if you don't seperate the air and the oil that the oil would get "frothy".
If I don't shut the ball valve before shutting off the car, I assume that when I restart the car, it would have to fill the accusump before oiling the engine. Is this correct?
Wouldn't the engine not get oil for a bit the first time you fill the accumulator?
Would I need to put a checkvalve between the pump and the accumulator so the oil doesn't just flow back to the pan? Or is this okay?
Sorry for all of the dumb questions!
Thanks for all of the help!!
Rob
The internal piston does prevent foaming of the oil and also allows the accumulator to be mounted at any angle - lying down, for example. Without the piston, you need to have the outlet at the bottom and the air at the top. A tall canister will keep foaming to a minimum.
You're correct - if you don't shut the ball valve, you'll dump all the oil into the sump and the engine will have to fill it up again. This is going to affect the oil pressure in the rest of the engine. I'm not sure for how long or how much.
If you're concerned about starving the engine when you first fire up, you can fill the accumulator about 2/3 full and then pressurize it with air to around 60 psi. That's not how Moroso says to do it, but it sounds better to me.
The accumulator should be hooked up to the pressurized part of the oil system. As long as the pressure in the engine is the same as the pressure in the accumulator, there shouldn't be any draining. A check valve would prevent it from working when it was supposed to!
Just to clarify:
If the oil pump loses its prime due to oil moving away from the pickup, wouldn't the oil in the accumulator just run back into the oil pan?
I was thinking that there should be a checkvalve after the pump and before the "T" that goes to the accumulator. Therefore, the oil from the accumulator would run through the engine instead of backwards through the pump.
Thanks again for all of your help! I think this is going to be easier than I was thinking!
Rob
It's supposed to run back to the sump - that's where all oil ends up. But it has to go through the engine to get there. That's where the pressure is needed. It can't really go backwards through the pump.
Keith wrote: for how long or how much. If you're concerned about starving the engine when you first fire up, you can fill the accumulator about 2/3 full and then pressurize it with air to around 60 psi. That's not how Moroso says to do it, but it sounds better to me.
That was why I considered the tire inflator compressor, just to use upon starting.
But that's only for initial installation. The very first time. Every time after that, the accumulator should have stored pressure from you operating it correctly - closing the ball valve before shutting off the engine.
I'm assuming the initial installation will be done somewhere where air pressure is available, if only from a bicycle pump.
The problem i see is that there is a bladder inside accusumps. You will need to somehow put one of those in to what ever you build. I really think that this is a case where spending $$$ is worth it.
Get a used one and document the price paid then vandalize it so it looks like a piece of junk.
No bladder, just a piston. We took the piston out of our Accusump (tm) on the advice of a local Porsche racer who had seen too many fail.
I've used a no-longer-airworthy aircraft accumulator.
Mine was a prop feathering accumulator from McCauley. it's about a 1 quart capacity so only good for pre-oiling a turbocharger.
Shawn
I used to run a homemade fire extinguisher version on a circle track car back in the '80's. Even painted it blue just to mess with the competition. It was Mopar powered, so access to the externally mounted oil pump for tapping into the oil system was easy. Used -12 hose w/ a ball valve, tank was mounted vertical. On mine, i removed the tube and cleaned out the tank, then drilled/tapped a larger fitting in the valve assy (removed the valve too).
All kinds of weird squirting noises coming from the engine on startup sounds like a good thing, but if you wait too long to start after opening the valve, it will take a long time to build oil pressure because you are also re-filling the tank. If that happens, you are better off to close the valve when starting, until the engine has pressure, and slowly open it to avoid a drastic loss of pressure while re-filling. Accusump used to sell a version that had an electric valve, it would be nice to be able to open/close that valve from the driver's seat.
Works great, but a proper pan would be better/lighter as you won't need that accumulator.
If you that worried about, why not just convert it to a dry sump system?
wvumtnbkr wrote: Just to clarify: If the oil pump loses its prime due to oil moving away from the pickup, wouldn't the oil in the accumulator just run back into the oil pan? I was thinking that there should be a checkvalve after the pump and before the "T" that goes to the accumulator. Therefore, the oil from the accumulator would run through the engine instead of backwards through the pump. Thanks again for all of your help! I think this is going to be easier than I was thinking! Rob
Why would there be a "T" for the accumulator? It only needs one fitting and one hose to it, one that goes to the supply side of the engine's oil system between the pump and the bearings. If you shut the engine off without isolating the accumulator the oil will simply come back out of the accumulator and through the engine bearings as the oil pump pressure goes down. There shouldn't be any way for it to "dump" to the sump without going through the bearings; it can't go backwards through the pump because that would require the pump to turn backwards, which would require the engine to turn backwards.
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