Accu-sump
 

Has anyone installed one of these systems on their 1984 to 1989 911? It is an addition to your lubrication system and consists of a small oil tank, one to four quarts, which is pressurized to reduce engine excessive engine wear during start up.

Any feed back would be appreciated or opinions

i think more use would be found from preheating the engine oil
pressure isn't to much of a problem on startup with a 911

You have a dry sump and a big oil tank that would make the accusump redundant. They work well on 944s and 928s, but are really only needed when running track tires, as normal cornering Gs are not sufficient to cause starvation.

To answer your more specific question, the bearings on a 3.2 are about the last thing that goes on the engine. Waiting until the engine warms up before using more than half throttle will add more life to your engine than anything else. This is IMO a cause of premature valve guide wear, but I am not a doctor or a Porsche mechanic, so I am prepared to stand corrected. I think that switching to Redline or a similar oil would be more to the point. LOL

The accusump is for pre-lubing the engine before starting.
You charge the reservoir before shutting down...and then release it into the galleries before hitting the start button.
The idea is to prevent dry starts.
It has varying benefits....some good...some redundant.
If you have the right oil in the engine...the bearings are still wet and by the time the crank has turned a couple of times...the pressure is already up.
Bob

Good for engines that don't have a dry sump.....

Well they also have some applicability to the 911 guys. In particular they are very popular with racecars to even out low pressure situations. As many of you know the 911, particularly the SC and earlier cars had oil-starvation issues during heavy braking and heavy left-hand turns because of the pickup location in the tank.

The Accusump will add pressure to the system if it drops too low, saving critical bearings and giving a little longer time for shutdown int ehevent of pressure loss for some other failure.

the motors will go 200k to 300k or more miles without these things... so...

There might be something in there though. In the early 70s my dad saw a number of big block Chevy crewcabs that were getting over 200K miles without a rebuild because the engines were never shut off. (building the Alaska pipeline) At that time the normal life expectancy of a big block cam was about 80K miles.

Not sure how much of the improvement was from avoiding the momentary lack of oil on startup and how much was from the fact that the motor was always warm.

my money is on the always warm part
oil pressure isn't a problem on a cold engine, it builds up fast, and during warm up the oil pressure will be higher then when the engine is hot... the oil however will be colder

manufacturers design their engines to warm up as fast as possible, hence the use of thermostat's to eliminate cooling during that stage of engine operation... and another reason why one should never warm up the engine by idling, because it takes longer...
so preheating the oil, is way more of use then pre-pressurising the system... it's a rather common practice for airplanes to preheat the oil tanks ...

I've installed two, but no pictures, and in both cases the accusump was installed in the cabin of the racecar because they were manual valves. The lines were plumbed into the pressure switch on top.

I suppose if you were creative you could install them into a T-fitting on any oil-line, though ideally you'd want it at the exit of the oil-pump pressure side... ...requiring tapping the case.

I read a post on here a few yeas ago from a respected member saying emphatically that an enormous amount of engine wear occurs at startup. I confess I don't recall the member's name or the thread. But in any event, if that post was accurate, then accusump might be a good choice even for dry sump motors. After all, rebuilds on 911's are outrageously expensive. Why go 200k if you can go 600k?

the stress at cold start, is because none of the parts are designed for cold running, all the specs are designed to be optimal after they had thermal expansion... hence the requirement to get it warmed up asap..

i fail to see what this accusump would do, my 911 had max pressure in a flash after starting, not even delay on the gauge, it's just there right away, cause the oil is thick

Let's look at the value of an Accusump from another angle...and let me ask a follow-up question.

Our supposedly "superior" dry-sump oiling systems are not all they're cracked up to be. The "S" hose from the engine to the bottom of the tank connects to the tank at the wrong end....heavy braking during a DE event will uncover the rear pickup point and you might as well have a wet-sump engine. It shoulda been placed in the front. There is more chance of a 1g braking action than a 1g acceleration ( !) action.

Some people baffle the tank ( do a search) and some add more volume to the bottom-end of the tank to help keep the pickup covered in oil.

Is there a way to plumb-in an Accusump to help with this problem?

- Wil

Accu Sump
 

My understanding of the system and value it brought to the table was how it reduced the wear that is incurred during start up. I also thought that this might be even more important in the case of cars that sit for long periods of time between starts. An additional benefit was that IT added an additional 2 to 4 quarts of oil.

Even if the benefits of reduced engine wear during start up were very small, anything that helped reduce the need for a rebuild would be worth doing. I have paid for three rebuilds over the past 25 years and they are nIT getting any cheaper.

On a separate nITe, has anyone increased the capacity of their oil tank? If so by how much. 911 engines are as much oil cooled as they are air cooled. I have always thought that one of the benefits of a dry sump system is that there is the ability to carry a larger supply of oil.

to much oil would cause problems with warm up again
an engine should warm up as fast as possible
more oil = slower warmup, and a running condition which is less then optimal and yields more wear

in winter time, some drive with less oil , because the engine hardly warms up as it should on a full 9/10 quarts

again, you'de have more benefit from an oil preheater, then from the accusump when it comes to preventing startup/warmup wear

Accu Sump
 

The oil temp can and is controlled by the thermostat which is part of the system. In the winter, here in Texas, when the temp is at 40 degrees the thermostat does not open on a short trip. You can check by feeling the oil lines in the front fender well. Granted, if the oil tank is larger it will take longer to reach the temp to open the thermostat.

In the winter I have had to block off the air flow one of the oil coolers in the front of the car. I have added a second cooler in the left front fender well in place of the washer bottle. In the summer at 100 degrees plus it's a different story. The additional cooler and oil lines have increased the oil capacity to 12 quarts at oil changes.

here is what i'm doing. i installed a 3qt accusump in the front abve the oil cooler duct. i'm running an-8 socketless hose through the interior to the port in the top of the case where the warning light sensor goes. i found a 10mm x 8an adaptor on summit racing's web site. i decided to add the accusump for the oil starvation due to g-forces reason, i agree the start-up wear is not a big deal on our engines.http://forums.pelicanparts.com/uploa...1182179412.jpg

Accu Sump
 

Does the system, Accu-Sump, stay under pressure until there is a "need" for additional oil? If it is needed does it re-set it's self?

quick questions,
how often does did the starvation occur,

how hard were you cornering when it did occur

do you think it would occur if you didn't have the fancy oil cooler setup you have now, with the longer oil return track to and from that front oil cooler and i presume a probably big front cooler

Accu Sump
 

There is nothing "fancy" about the system other than an addition oil cooler which is about the size of the cooler in the right fender well. The challenge I face is not getting the car to perform on the track but to survive on the street and deal with the excessive heat we have here in Texas. I do not like to see the oil temp get over 200 degrees and never over 220 degrees. The problem I had before adding the additional cooler was when the car got really hot ,as when you are caught it traffic for a couple hours with the ac on, it took for ever to cool down once the traffic began to move.

I just returned from New Mexico and running at 90-95 mph with the ac on my oil temp was 180-190 degrees. The pressure was always higher than the rpm of the motor, ie 3000 rpm with 4 bars pressure.

My interest in Acccu-Sump is that it might mitigate any "start up wear". I plan on keeping the car for a long time.

questions were aimed at gestalt1, who has an accusump in what looks liek a race car, not a street car

and most folks, if not all on this thread, so far has said, no use, oil pressure on startup is good on a 911

and i mentioned 2 times, that oil temp , warmup, is way more important...

flogging a dead horse here

Obviously, we can rationalize most any Porsche related gizmo but if you are trying to "extend the life of you motor" by using an AccuSump you are wasting your money IMO. The bottom end of these motors is already one of the last things to wear out. (As long as the squirters aren't blocked.) Tear a few apart and you'll see.

The valves guide are the first to go and no amount of pre-oiling is going to make them last longer.

In my non-expert opion, heat is the enemy of these motors. The air/oil cooled heads on our motors have pretty poor thermal control compared to a water cooled car. The valve guides (and even the valve springs) suffer as a result.

Put a fan on you oil cooler if you are seeing hot temps in traffic and change your oil more often.

-Chris

Stijn, i have not finished my car yet so i really can't comment on the functioning of the accusump in the real world. it does store oil under pressure, when there is a drop in pressure it releases this extra oil. when the pressure is built back up the accusump re-stores the oil for the next time the engine oil pressure drops. i went with it because it was cheaper than a custom oil tank and it is plumbed directly to the main oil galley. i don't think it is needed on a street car, mine is a barely street legal race car.

How much are they?
Gestalt - looks like a nice install!

Doug

Accu Sump
 

Here is the address. I estimated that it would cost about $450 for everything. http://www.accusump.com/

Assuming you use the automatic control switch, which would allow you pressure in the event oil starvation in the tank:

What happens at low engine speeds and oil pressures when it dumps an extra 2 to 4 qts of oil into the system? My engine idles at low pressure, probably low enough to trigger it pressurizing the system.

That much extra oil would probably overfill my tank or at least cause a bunch of oil to end up in the intake.

Doug

i think i got the accusump for $280 with the electric valve. the an-8 hose, ends and adaptors is about another $100.
-matt

I read the lowest threshold switch operates at 20 to 25 psi. If you engine idles at or below, it will dump oil into the system.

Let's connect the Accu Sump to the Off-Topic thread area and let it pump away...

Actually, let me add my .02 to this discussion before we decide it's not worthy of inclusion in the main forum.

For a few seasons now I have been racing my 911E on Hoosiers.

Porsche braking being what it is, I have seen braking forces well in excess of 1g on my DL-90 data logger.

As was correctly stated above by Wil, this kind of braking causes the oil in the tank to slosh away from the supply port, which is located in the rear of the tank.

I have an adjustable low oil pressure light which is set at 20 pounds. Under hard braking, the light illuminates frequently. NOT good for the pressure pump or bearings to be starved for oil.

The correct location to plumb the Accusump is into the oil pressure port next to the engine thermostat. This connects to the main oil gallery. The fact that Porsche measured the oil pressure originally here, and then moved the pressure sender to the other end by the chain box cover so they could install an oil pressure idiot light by the thermostat is immaterial.

That's all well-known. Now to conjecture.

My BELIEF is that plumbing an 18x1.5 fitting to the port and then running a line to the Accusump would smooth out the pressure fluctuations, with the side benefit of pre-oiling. The thing about race cars it that they tend to sit in storage for long periods over the winter (well, mine does) so being able to pressurize the system after a few months is helpful.

HOWEVER and it's a big However, this installation is unsuitable for owners of Mechanical Fuel Injection cars . . .BECAUSE. . .

There is a banjo fitting on the port for the pressure sender that sends engine oil pressure to the MFI pump inlet. While there is a small-diameter orifice in the inlet to the MFI pump, it's still a calibrated leak, which would cause the pressure to bleed down. For carbureted cars, I wouldn't hesitate, but for MFI, not a very good idea. In addition to the difficulty of plumbing everything.

Now, why not convert the pump to have no oil from the engine a la RSR? Well, I asked Gus about that very thing, and it's a very expensive modification. If you fill the pump with oil and plug the supply and return lines, and don't provide the vent on the top, the pump will pressurize and blow the oil out. So the red vent must be installed. (Gus says this was originally done on engines with "a lot of vind in ze crankcase" i.e. the pressure fluctuations in the crankcase would blow the oil out of the pump through the return line.

Also, if you plug the oil lines, you will have to remove the pump every time you want to change the oil in the pump. Removing the pump is about a six on the Scale of Inconvenience, with under-dash electrical work about a seven.

SO where does this lead us? I have an accusump for sale, manual valve, never even been out of the box. I would take $150 not including shipping from the first private message accepting my offer.

Good luck!

john is right, an accusump will not work with mfi. I'm using an efi system so i don't have that problem. just to clarify, on my sc case the oil pressure warning sensor is a 10mm, not 18mm. the pressure guage sender is 18mm. the 10mm is very small compared to the 8an hose (and the 8-an is on the small side of what is reccomended). i'm not sure this is important because i've seen it plumbed into the case this was and there aren't other options really.

The M10x1.0 VDO sender threads into a fitting in the case. The threads on that "reducing socket" are M18x1.5 if I am not mistaken.