All about Accusumps

[frijolee]

One of the few threads I made sure to save from the other forum.  As someone who's lost an engine due to oil starvation I'm a true believer...

First the results of the poll I posted.


And now the wayback machine:

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Most folks here are tech savvy enough that they?re familiar with Accusumps.  Canton?s Accusump website has a general concept of ops that is a good read if you need a reminder.

My 0.02: having previously blown a motor due to oil starvation, if you ever intend to road race your car I?d call an oil accumulator almost mandatory, particularly in an LS1.  Yes, you can overfill the plan and cross your fingers but that?s certainly not my style.

First a disclaimer:

Michael?s (Race Driver?s) LS1 oil pan baffle is a good piece, I like the design and I run one myself.  However, it doesn?t unilaterally solve the issue of potential oil starvation purely due to the limitations of a gravity driven drain-back to the pan.  The LS1 drains back down the valley cover so it seems susceptible to pinning a great deal of oil in one cylinder head under high RPM and high lateral Gs.  No amount of slosh control in the pan can prevent this, it just aids in not uncovering the pickup when the level drops (and it will) much like overfilling your oil pan does.

I like Accusumps both because the concept of pre-oiling is sound and because a couple extra quarts of oil is a lot of insurance.  The only downside is that when the Accusump discharges the level of oil in the pan may increase more than desired, resulting in slight HP loses due to added windage. 

Valving: I don?t entirely buy Canton?s valve descriptions (and associated capabilities) from the web.  Here?s what they say:

[SIZE="1"]What valve do i choose?
The valve controls the flow of oil between the engine the Accusump. Our Turbo-Oilers do not require any valve system to restrict their oil discharge as they are intended to discharge all their oil at shut down. However our Accusump Oil Accumulators require a valve to close off the unit after shut down in order to hold oil pressure inside so it can pre-lube the engine upon the next start up.

In hard core racing applications a manual valve is used for simplicity. This valve can be mounted either on the Accusump directly or plumbed anywhere convenient along the feed line. With this valve, the operator has to manually open the valve before starting the engine and close the valve before shutting the engine off.

For applications where more convenience is desired or where it is difficult to access a manual valve lever a standard electric valve can be used. The standard electric valve is designed to slowly refill after any oil discharge and is ideal for 'daily drivers', boats, or an RVs. The electric valve can be opened and closed from a remote dash-mounted switch or it can be wired directly into the ignition so it will open and close automatically when the ignition is in the 'on' or the 'off' position. For high performance applications that require rapid refill and constant discharges we recommend the EPC electric valve listed below.

For those looking for the convenience of an electric valve and the fast refill rate required in racing applications our (electric pressure control) E.P.C. electric valves are recommended. The pressure control system keeps the electric valve in the off position during times of normal oil pressure. With the valve in the off position it is able to quickly recharge the Accusump with oil pressure after discharge, thus being ready for the next oil surge. When the engine's oil pressure drops below the EPC Valve's preset level the valve opens and releases the stored oil in to the system. Like our standard electric valve the EPC valve can be wired to a remote dash-mounted switch or can be wired directly into the ignition so it will turn on and off automatically when the ignition is in the 'on' or the 'off' position.[/SIZE]

I say: there?s some blatant misinformation above.  Don?t drink the kool-aid!!!

For starters, the electric valve is the same regardless whether it?s being used in conjunction with the pressure switch (thereby making this an EPC setup).  I called and confirmed this is true with Canton?s tech support.  It?s also evidenced by the fact you can buy a pressure switch upgrade to the standard electric valve.

So what really are the pros and cons of the various valve setups?  Any of the valves can be used to pre-oil and all will allow added oil on pressure drop.

The manual valve is just ?? ball valve, it?s dead simple and can be bought with a remotely actuation via a push/pull cable.

The electric valve is essentially an electric check valve.  It always can flow toward the accumulator but with the solenoid energized it flows either direction.  The orifice on the valve is ?? equivalent so the only difference in flow vs. the ball valve is that there?s pressure loss in negotiating a couple tight turns.  When the valve is closed there?s a bit of pressure required to overcome the spring in the diaphragm seat (relatively small) when the solenoid is not energized.

As such, an electric valve by itself will behave near identically to a manual valve when it?s turned on.  However if the system is off, you need to be aware that you may lose some oil level in the pan as the accumulator pumps up to its max pressure (behaves like a check valve).  This introduces potential operator error in measuring your oil level if the Accusump isn?t fully pressurized when you measure it.  If you run just an electric valve I would leave the switch on at all times (maybe even buy a switch with a lock) and just use the ignition to turn the system on and off.  This way the switch becomes just an override if you?re working on something else that requires ignition on.

The description Canton provides about rapid refill with an EPC valve is blatantly wrong.  In fact, because the EPC turns the valve off, the EPC system will refill somewhat SLOWER than the plain electric valve (again due to pressure of the diaphragm seat to overcome in check valve mode).  In both cases this is the exact opposite of what Canton describes.

However, there are advantages to intentionally utilizing a slow refill and occasional discharge.  Both the manual valve and an electric valve (assumed to be always on) will purely float with the oil pressure.  This means with an engine increasing RPM the system will actually steal oil from the bearings in order to fill as the pressure rises.  Conversely under conditions of slowing RPM the accsump will be dumping oil back toward the bearings. 

An EPC will steal oil more slowly on the rev up and then store it at max pressure to be released at the max pressure.  This means that when it does open oil enters the block with more force to cover you when you need it.  The EPC has a further advantage if you must run and electric valve that the solenoid should last longer because it won?t have a 100% duty cycle.

So assuming your want a pressure sensitive system the next question is at what pressure you?d want the system to turn itself on and off.  Canton recommends just below your minimum pressure.  With a ported LS6 pump and 10w40 oil I see between 35 and 60 psi in normal driving conditions so it?s right on the threshold of which valve I would choose (20-25 psi or 35-40 psi)

The only downside of having the EPC system having an open valve too often is the inconsistent amount of oil (assumed always to be in excess) within the pan.  However the change in oil level really isn?t that much and it should be noted that this is the same downside found with ?always open? setups (ball valve/plain electric valve) that seem to work fine.

[INDENT]Math Tangent:

-A 3 Qt Accusump measures 16? L x 4.25? OD.  If I guess that the ID is 4.00? and that the end caps and piston occupy 2.25? of overall length I find the starting volume is 2.99 Qts.
-However you should note that this is TOTAL available volume which includes space to be pressurized.  Also note that these numbers are approximate as similar assumptions on the 2 Qt version (12? L x 4.25? OD) yield 2.12 Qts so the math isn?t perfect.
-Boyles law (ideal gas law simplification) says that PV=constant at constant temperature.  However, P in all equations must be absolute pressure (not gauge pressure).
-Accusump recommends between a 7 and 15 psi precharge.  If we start with a 10 psig precharge this means 24.7 psi absolute (psia henceforth) occupies 2.99 Qts.
-At idle (fully warmed up) this same quantity of air is now under ~35 psig (49.7 psia) as oil enters so the air occupies 1.48 Qts and I have 1.51 Qts of oil in the Accusump. 
-When revved up more oil enters and the air compresses to equalize at 60 psig (74.7 psia).  This means the air occupies 0.99 Qts so I have 2.00 quarts of oil in the tank.
-Nominally, the difference in oil level between revved and idle is only ~1/2 Qt.  This is why always on setups get away with this just fine.[/INDENT]

The reality is that I?d generally prefer incoming oil at greater pressure which only happens with a pressure sensitive system that can turn itself off AND to come in on a pressure drop that?s just a smidge below my choosen threshold.

As such I?m looking at aftermarket hydraulic pressure switches so I can dial mine in at right around 30 psi.  Splicing one in is as simple as picking up some AN union fittings with 1/8? NPT ports.

In terms of installation and plumbing, I?ll do a separate write up of my experience in my build thread but suffice it to say that you can?t fit the normal 8M16C80MX Parker fitting that David Farmer recommends for Corvettes behind an F-body/GTO alternator. 



This means you either have to plumb this system into the rear galley port (where the oil pressure sender lives) or T it into a remote filter/oil cooler line.

So how about it, do you run an Accusump?  Why or why not, and what valve setup did you choose?  (I'm assuming capacity is mostly a matter of packaging so I'm leaving that off the poll)

One last question on Accusump theory:  What happened to the air bubble you sucked in when the pickup went dry?  Is it just vastly minimized because the instant the far side of the pump sees air the pressure drops and the pump freewheels without driving more air into the system?  That doesn?t seem right because pumps will self prime with air in the pickup tube so they must be able to drive air.  Maybe the bearings don?t care if a bubble comes through sputtering at high psi but I've always been curious.

Your thoughts?

-Joel

PS If you have any good Accusump info or just want to share your experience feel free to add it here as well.

[frijolee]

A friend of mine runs the 3qt on his LS1 drift car. A little off road excursion ripped a huge hole in the pan. He had no idea, dumped oil all over the track and continued at full throttle for another 45 seconds before they black flagged him off the track. The result was 0 damage to the motor. Convinced me that I should definitely get one.



shiny crank journal

[frijolee]

Here's a thought regarding the original post in this thread.  The Accusump is a racing device, not really intended for street use at all.  As such, unless you're in the pits you should be running at 3000+ RPM at all times.  This includes downshifting into corners.

I haven't logged oil pressure over an entire lap, but under normal circumstances you should be seeing at least 55psi, and often more like 70-90 psi.  What this means is that when the motor is being taxed to the max (in corners, under partial throttle) the motor is probably spinning fast enough to push the oil pressure quite high.  It's also worth noting that some of the highest pressures are seen right as you're downshifting into a corner--as high as 120psi.

Under these circumstances the accusump is essentially completely full of oil.  (Only 10-15% of the volume is air at that point.)

This is why the pure racing setup use an EPC of 35psi or higher, because they should NEVER see the pressure drop that low under any circumstances on the track except in the pits.  And if they do, they want to immediately introduce pressurized oil into the system.

However, if on the track you do not shift at redline, and you spend a lot of time in the lower RPM ranges, the higher activation pressure of the EPC will mean you are running a lot of extra oil in the motor which will cause losses, blowby, and smoke spewing out the back of your car especially on decel.  It will be just like you overfilled your car by 2-3 quarts.

But anyway: my main point is that checking your oil level should be done in the following way:  Warm up the motor, then shut it off and purge/cycle the accusump and set the initial pressure to 7-10 psi.  Turn the motor back on and rev to 3-4K RPM for 10 seconds, or until the pressure in the accusump stabilizes.  (I usually see 70-90 psi at the accusump gauge.)  Close the valve (manual, EPC, whatever), shut off the motor and record the pressure on the gauge.  While the valve remains closed (and the accusump pressurized) fill the motor to the desired level.

Note that unless you use a mechanical valve and keep the accusump closed, most of that oil will flow back into the motor under street/cruising conditions, resulting in a lot of windage losses and other high-oil-level issues.  Again, this system is really designed for the track.  If you run a high-pressure EPC, you should probably just purge it and shut it off for street use.  I run the lower pressure gauge because, under normal operating conditions, the engine pressure should never drop below 20-25psi.  So essentially the accusump charges and stays filled for the entire trip, never discharging.

But I do the process described above before I hit the track to make sure that I have enough oil in the motor with Accusump under full pressure.

-ch

[frijolee]

I now have over 400 track/race miles (mileage from AIM dash) on my track only car since July 2008. This includes a 60 minute race with a pit stop (what a blast).

 I occasionally miss down shifts and have recorded several 7200 RPM over revs, oops. Additionally, I've taken up the bad habit of rolling off the staging grid and frying the rear tires through 2nd and 3rd gear to my 6500 RPM redline. My excuse for this behavior is to warm up the rears as we only get 3/4 of a lap before the green at my local track. The real reason is it sounds so good. My point is I'm not babying the motor and have had zero problems with the swap/power train.

There are 3 benefits to the Accusump that I like:

1. It looks good in the back of my race car interior.
2. With no insulation or other sound deadening material, my car sounds like it's coming apart when you start it without pre oiling via the Accusump.
3. I feel better knowing it's there. This may be the most important one.

Off subject: We have been running some tire tests including a staggered setup with 245 fronts and 275 rears.

Bob

[frijolee]

It won't fit behind the alternator unless you're running a vette setup or alternator relocation of some kind. You need 1/2" more room than exists to get the sharp 90 (per david farmer's ls1 accusump instruction) out the block to work.

I used the top rear location and -8 AN hardware everywhere. From sump to engine it runs:

Accusump in drivers bin (oil end raised slightly per recommendations)
-90 f AN to hose along frame rail
-90 f AN out firewall below fuse box
-oem pressure gauge w/ m-f AN gauge adaptor (shows accusump pressure)
-pipe to m AN adaptor
-electric check valve
-pipe to m AN adaptor
-pressure switch w/ m-f AN gauge adaptor
-aftermarket pressure gauge w/ m-f AN gauge adaptor (shows engine pressure)
-90 f AN to short hose behind plastic fender liner
-90 f AN through firewall at fender (below clutch MC)
-m-m adaptor
-straight f AN to hose along firewall lip
-straight f AN
-m16x1.5 to m AN adaptor at block

I've just barely gotten the car back up but it seems to be working great thus far and all the hardware packages under the fender so it's very unobtrusive.

-Joel





The sump itself is tucked under the edge of the storage bin with the edge trimmed to fit and allow gauge readings. 

[frijolee]

FYI I'm running a 3 qt.  One end is bolted to the frame rail at the edge of the bin, the other to the vertical face of the plastic/composite bin frame.

Link to adaptors is here...  You can find a lot more with a search for "male female 1/8 npt port" on summit (all sizes, colors etc).

I'm running the Aeroquip push to lock fittings w/ heat shrink on the outside to keep the braid from fraying.  They're not quite as solid as traditional sleeve/collar AN fittings but the fact is that they're rated for 300 psi so it shouldn't be an issue and they were a lot easier to use. 

I ran my hose inside the car under the carpet.  Your exposure to fluid goes up but the odds of failure go down so on net I decided that was the way to go.

[frijolee]

I'm now up to 673 practice or race miles post swap. This includes 2 endurance events. I'm now running Dunlop slicks on 10.5 X 18 wheels. The reason I mention the tires is Lateral Gs are to a point that I'm doing neck strengthening exercises.

Mazcare/Charlie systems are flawless. Do it like Charlie recommends, leave the max RPM stock (6500 in my case) and have fun!

I've got to have my car completely sorted and quick! The 3rd Gen vs 2nd Gen V8RX7 road racing shoot out is looming closer and closer :ohnoes:

[frijolee]

Sweet I just pulled the trigger on pluming mine to the factory sender at the rear of the block as well. 

I'm going to be hooking up the AeroForce gauges in the factory oil and temp gauge locations as well here.  So this ment the sender for the oil is going to get moved to the Lingenfelter oil cooler plate. 

This requires this adapter. 
Auto Meter 2266 - Auto Meter Metric Adapters


Thanks for the help and the pics here guys I will post mine when done.

[frijolee]

ok I did some oil control mods today when I had my motor apart. 

Since I just planed on pluming the accusump in the oil sender location.  I was double checking my motor's block today to make sure I have a 01 block.  When I had the rear cover off the motor I was looking at the oil gallery and noticed how small the oil sender hole necks down to.



So I did some thinking and I recalled reading that Canton recommended the larger line the better for the most part.  They said a dash 10 is really what is needed for the 3Qt and the V8 motors our size. 

So I then did some measuring and then went to drilling I made that same hole a 1/2"   


I will have to say this is not for the faint of heart let me tell you.  Not only are you drilling a hole in the block and trying to keep metal shavings from going into oil ports and the pan, but also you have to make sure that you do not mess up the threads for the sender port. 

Then I polished the front inside part of the oil pan to help return oil to the pickup.  When I say polished I mean I can see myself in it! 
So what are the thoughts behind these mods guys?  Sorry but they are cell phone pics and I was using a LED flash lite to help.

[frijolee]

Also forgot to add that I shimed the oil pump .125"

It was not really that hard.  Just be sure to take your time.  I will make this note I dont think this can be done on 99 and older blocks.  Look at the rears of them in this pic.

97-99 on the bottom



Whats strange is I have the passage like the top block but I also have the extra hole in the middle like the lower one.

[frijolee]

Much cheaper options for check valves:

-8
Race Pumps 1108 -

-10
Race Pumps 1110 -

1/2" NPT
Moroso 23875 - Moroso One Way Oil Check Valves

[frijolee]

Ok found this today and I'm leaning towards the head monted pump for my car with the C6 LS2 pan. 

http://aviaid.com/pdfs/115-complete_listing_of_wet_sump_and_dry_sump_oil_systems_for_ls1_through_ls6_chevrolet_engines.pdf

[frijolee]

Had an issue with one of our Accusumps working slowly. The 25psi pressure switch was holding open circuit intermittently under KOEO conditions or just wouldn't pre-oil for same reason. Removed switch and tested with same results, blew it out with brakeclean and air and it works better than when new. Looked like it was lightly crudded up when I cleaned it out. All good now.

[frijolee]

And that was at least the majority of the big stuff for back when...

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Question for those who have shimmed their oil pump.  How much did you shim and how much pressure difference did it make at idle?

In hot weather I see about 33 psi at idle (w/ 10w 40 dino oil) and it's just enough to trip my Accusump valve into activating.  I'd love to see it idle at 38 so my oil level would stay a bit more constant in the pan (and accusump at a bit higher pressure on average).  It seems to me that this is the one downside of running the 35 psi pressure switch.

If I ever pull my motor again I'll do Josh's trick opening the passage restriction at the back of the block.  Other than that the only other add I'm planning for the oil system is to add an LED into my gauge pod so I know when the Accusump is activating.  I'd feel pretty dumb if I lost an oil line and then let the system drain without knowing it was happening.

Good luck and best wishes for your motors living long happy lives...

-Joel

[frijolee]

Question for those who have shimmed their oil pump.  How much did you shim and how much pressure difference did it make at idle?

Still looking for an answer to this...