Accusump - some data
 

First event of the 2018 fall season for me in Arizona at Arizona Motorsports Park (AMP). I tested my new Sparco EVO seats and 6 point harness setup and was able to get my personal best time in the 3rd session. What a difference that setup makes!

I also decided I would attempt to quantify the effectiveness of my 2 qt Accusump setup to see if it makes any difference. I used my Autosportlabs Race Capture Track setup with AnalogX reading oil pressure and Accusump ON solenoid voltage.

This data was taken from Session 2. In order to minimize any noise (such as the effect of oil temp on oil pressure), I turned the Accusump OFF then back ON on adjacent laps (laps 2 and 3). I'm assuming that my driving is similar for those 2 laps as well. I'll post a rendered video with data for the same laps when I have some time.


http://986forum.com/forums/uploads02...1539574297.jpg

The X axis is basically time, with the Lap count showing as a stair step at the bottom. In Blue, I'm showing the voltage of the Accusump solenoid. Spikes indicate it is activated (and dumping oil during that short time). The Orange points show the Oil Pressure as measured at the inlet of the oil filter (so not directly at the oil pump). And lastly, in Grey, is the Oil Pressure as measured at the standard location on the passenger's side cam cover (head). Outside air temp was roughly 75F and oil temperature did not climb beyond 225F. I was running Federal RSR595 tires and lateral Gs were getting up to 1.05-1.15 Gs. I also have an X51 style oil baffle.

Although this is only a single data set at a single track, I think it's pretty clear that the Accusump has a measurable effect. What I can see is that the VC Oil pressure never dips below 27 psi vs 22 psi when Accusump is OFF. Looking at the Pump Oil pressure, it never dips below 44 psi, but dips to 30 psi when turned OFF. This larger effect on Pump oil pressure can be explained by the fact that the Accusump feeds into oiling system much closer to the oil filter than to the pump, and there is a check valve that helps to build up the back pressure.

Is it worth it? Will this prevent oil starvation? I don't know, but just looking at this, it certainly doesn't make it worse.

Let me know what you think:)

PS... I don't have any relationship with Canton Racing:) so I'm not biased on way or the other. I just believe in the power of data:)

Thank you for sharing, very interesting!

Thanks for this! The graph is pretty small.....but one thing really stands out. The VC pressure doesn't really vary that much and depending on resolution may be all but useless in determining rapid changes in oil pressure due to cornering loads, especially with an accusump installed. It may be okay for a startup and that is it.

According to your data it looks like one has to have your transducer at the filter inlet to get any meaningful feed back in the cockpit, while cornering. The 996 oil pressure tap location in the head is not going to tell you much...

Here is the 4 minute video of both laps starting with the Accusump turned OFF then back ON for the following lap.


https://youtu.be/E5757Nq36fw

Great video! This is very well done! How did you get the solenoid indication on there......what are you using to knit this all together

It looks there is pretty good indication at the VC....I will take back what I said.

I am surprised that the accusmp does not take more of a bite out of pressure drop loss.

Nice job catching that other car - did you pass him on the lap after the video ended?

Thanks:)

Yes I did. I believe that was the 2009 Cayman owned by a track budy.
I ended up getting my personal best for that track during Session 3 @ 1:56.4. I attribute that to the new Sparco seat setup, but I also have a new tune from EVOMS here in Phoenix. The car feels strong. The only thing I would say is that with my current setup, the car feels super well balanced, but with maybe a touch of understeer. Might have to consider adj. LCAs in the front.

BTW, the Canton filter did well as far as I can tell. I'd like to crunch the oil pressure data some more and compare it to last season with the NAPA 1042 filter to see if there is a difference. Hot idle pressure did seem to be a little higher. I'll report back.

Refresh my memory, what are you running now for suspension (lowering springs?) and what is your current front alignment?

I'm still fairly well balanced on the M030 USA sport springs and Koni FSD with 225/45/17 front and 255/40/17 with Tarett GT bars, still some understeer but not terrible, would like to dial it down a little more but don't want to get to a major oversteer situation. If I could get just a touch less understeer I would be happy, and maybe I can get there with driving style changes :)

I use RaceRender Pro to edit and render the videos.
My camera is just an old GoPro, but still works fine.
My data setup is the Race Capture Track device on local CanBus. I also attached an Analog input module onto the CanBus, allowing me 4 Analog I/Os. I use those for Oil pressure and Accusump Air side pressure as well. I'm able to get the Accusump solenoid signal by using one of the 5 VDC Analog I/O channels, but since the coil is 12 VDC, I have to run it through a relay. Then, in the RaceRender software, I added the yellow blinking object to come on when the signal is at 5VDC (meaning the Accusump is ON).

As far as the effectiveness of the Accusump at dampening the pressure drop spikes, it does seem to help. My take on that is that the spikes happen so quickly and that the Accusump solenoid taking perhaps 20-100 milliseconds to open the valve, and another delay for the oil flow/pressure to build up to compensate for that dip, by that time some of the pressure drop has already occurred. Some of that can be improved by increasing the Accusump Pressure on the Air Side. That would allow for a quicker reaction, but at the expense of a lower volume of oil. I think this could be tuned to be track specific. Short track, short turns, high pressure and less oil volume. Long sweeping turns track, low pressure with more volume.

Yes, same here, would like just a touch less understeer. I'm running H&R sport lowering springs with stock struts. I have the Eibach swaybars, front is fixed, rear is adjustable (on middle hole). Tires are 225/45R17 in front, 255/40R17 rears. Alignment is neg 1.8-2.0 deg camber in front, and 2.5 rear. Front is maxed out for negative camber. .06 Toe in on rear. 0 toe in front.

I thought I would share my idea concerning the inherent time lag using the Accusump with pressure switch operated solenoid valve.

Knowing that oil pressure dips occur when lateral Gs spike to approx. > 1G, what if I modified this setup to include an adjustable accelerometer switch circuit in parallel to the pressure switch circuit. The idea would be that one could adjust the switch threshold to 0.8 or 0.9 G to open the solenoid valve just a tad earlier than the pressure switch would. This would in effect open the valve slightly before the pressure drop occurs... and keep it open for a minimum amount of time. The goal would be to smooth out any large pressure dips even further.

why not take the pressure switch out of the equation all together? without the pressure switch, the accusump immediately oils whenever there is a drop. the concern as per the canton website is that you might run out of oil if it is supplying a lot without recovery ...

Importance of Accusump Valve Selection & How to Choose.

but perhaps go to a 3 quart instead of a 2 quart unit?

perhaps bypass the pressure switch for a session and see what response is like.

edit to add - my gt6 race car has an accusump with a manual valve, but currently no way to monitor pressures (it's from 1968 and a very analog machine ...)

Yes I think I will do that next week. Re-wire to add switch for Bypass or No Bypass.

I do think that chasing rapidly fluctuating oil pressures with a pressure switch and solenoid valve helps some but ideally maybe a switch with adjustable Discharge/Refill setpoints would work better so that you can fine tune it. I still think that a G force based sensing system could be tuned independently of the inherent oil pressure changes /levels occurring due to different oil types/viscosity, temperatures, engine RPM and track conditions.

when we are dealing with drops over fractions of a second, the time for the pressure sender to detect and open a valve is significant. if the only downside to having the valve open all the time is potential depletion of the pressurised oil supply, then using an accelerometer to open the valve in an anticipatory basis is a good compromise. OR, i presume you are using the 40 psi switch; what about the 55 psi switch that might catch dips a little sooner?

I had toyed at one time with the idea of running an accusump with no valve, and having it open all the time. Since I run my oil a little bit low, at times when I was idle and all the oil was out of the accusump, I would be a tiny bit high but I figured that would be OK at idle. I would lose the ability to pre-oil the engine before startup, but since I don't have that capability now anyway, that wouldn't be a loss. My thoughts were:

2 QT Accusump
Set the air pressure to something high, like 50 PSI
I had a formula in a spreadsheet (that I think I have lost) where I could play with the base air pressure and the running oil pressure and it would show me how much oil was stored at that pressure

Then when driving, there would always be an available quantity of pressurized oil, with a min pressure of 50 (or whatever I set to be the min, and at that pressure all the oil would be out of the accusump) that would be available to stabilize the pressure in the event of dips.

I had forgotten that my fuel filter was in the tunnel so I can't put the Accusump there and so the idea fizzled... And maybe it would have fit anyway since I was going to use a 2 qt unit and no valve?

Looking at the real time data in the video above, the 60 PSI air pressure in the accusump, tells me that the oil pressure on the exit side of the accusump was only getting up to 60. So I would plug 50 into my spreadsheet as the base pressure, and then 60 as the running pressure, and it would tell me how much oil would be in the accusump, pressurized at 50 or above, to be available.

Maybe I decided this was useless and so that is another reason why it fizzled :)

The plus side of this system is that it is fire and forget, no switches to turn on or off, or manual valves to turn on or off.

The minus side is that it wouldn't hold tons of oil and might not be good for really long sweepers if there were long dips. And there is no pre-oil capability.

Looking at how the accusump works in the video, I might revisit it, if I can find my spreadsheet, I'm not sure if I have the energy to recreate the formulas for volume, pressure, etc.. that I used.

Since I don't think anybody else runs it like this, they may have already done the work of figuring it wasn't a good idea :)

Thank you for taking the time to share the data.

Mike

Here is the data comparing the NAPA 1042 filter with the Canton Racing Billet style oil filter, older style with Hex bolt on the bottom. The whole idea behind a racing filter is more flow and less restriction (pressure drop), sometimes at the expense of filter particle size efficiency.


http://986forum.com/forums/uploads02...1540005975.jpg


For the NAPA 1042, the data was taken in March 2018 at AMP.
For the Canton Racing, the data was taken just las week October 2018.
Both clockwise. Air temps about the same.
In both cases, I only considered the data for the last 2 laps of the session so as to have engine temp as steady and high as possible, and also only considered the Accusump Air Side Pressure as being the equivalent of the Post Oil Filter pressure when it was oiling (valve open). The NAPA 1042 is rated at 21 microns and 9-11 GPM, and the Canton Racing filter element is rated at 8 microns and 15 GPM.

I was surprised to see that the NAPA 1042 filter did somewhat of a better job, and about the same for the Pressure Delta across the filter. It then dawned on me that the 1042 has an anti-drainback valve whereas the Canton does not. This is important and can affect the effectiveness of the Accusump by eliminating the oil back flow when the Accusump is oiling. This also could explain the higher pressure values and lower standard deviations for the 1042.

What's interesting also is the negative pressure delta across the oil filter. But after giving it some thought, I believe that makes sense since that would happen when the Accusump is oiling initially when the Pump pressure is low from the sudden lateral G load.


This does not mean the Canton Racing filter is no good. It just means that for my set-up, it does not work better than the NAPA 1042 (at least from the limited data).

I thought about using the 55 psi pressure switch. I think the issue is that the oil pressure would be mostly bellow that, so in effect it would be always open. Today I installed a manual pressure switch "bypass" toggle switch so that I can keep the valve always open when needed. I will test that next weekend at AMP again, this time with PCA. I will set the Accusump Air pressure at 15 psi. This should give me 1.5 qts in the Accusump @ 60 psi, then 1 qt @ 30 psi, so about 0.5 qts to play with in real terms. If you start with 30 psi, the starting volume is 1 qt @ 60 psi, and @ 30 psi, it becomes 0 (empty). In theory, the response time is quicker at higher air side pressures, but you also start with less oil.

Was at AMP yesterday with the PCA group and logged some more data with and without the Accusump Bypass switch. This is a switch I installed to be able to keep the solenoid valve open, effectively bypassing the pressure switch.

http://986forum.com/forums/uploads02...1540740907.jpg


The first session is from a few months ago with NASA at the same track, but with the NAPA Gold 1042 oil filter. The last 3 sessions are from yesterday. I turned on the Bypass switch only for Session 2. I did a fresh oil change with 10 qts of M1 15W50 prior to yesterday's event. I also increased the Accusump air preload to 15 psi from 7 psi previously.

Very similar numbers for all 3 session yesterday, with and without the Bypass switch. BUT, the interesting thing is that the Accusump did not trigger at all during sessions 1 and 3 with the bypass switch OFF. Looking at the pump pressures, it looks like the pressure did not go low enough (35 psi) to trigger the Accusump. The only possible explanation I see for this is that the oil level might be higher with the increased air side pressure. This pushes more of the total oil volume in the sump and less in the Accusump. The electronic oil level gauge was showing 1 bar above full with the Accusump partially empty. Either way, I am happy with the performance of the oiling system yesterday with the lowest VC pressure at 29 psi.

Next event is at Bondurant with NASA and I will collect more data with the bypass ON and OFF. My belief is that keeping the bypass ON with normal oil levels should help reduce the oil pressure drops.

so, one of the things i am getting is the pressure drop across the filter. it seems high. i note that lne changed the filter they specify. i'd done a bit of research into filter elements - oem is 30 micron but a very large filter element AND has a bypass (not sure what pressure it bypasses at). the napa 1042 is 23 micron AND the element is much smaller in area and no bypass, so strikes me as a bottleneck in the system, and probably why lne went to their latest washable filter with a 60 micron size (they chose less filteration for better flow for a reason i think).

i think the accusump pressure switch is at the accusump, so should track the pre-filter oil pressure closely, yes? so, thinking that the 40 psi switch was spec'd based on a filter that flows better, and with the current config you should consider a higher pressure (55 psi?) switch to be more responsive or, as yu are finding, run without the switch and just let the accusump swing - did you get any indicators that the accusump was depleting itself after a long sweeper or turn complex? otherwise, i think more and more that a remote filter mount with full-size filter is the way to go.

Hey RK,

A couple comments:

- I'm using a remote oil filter with the Canton Racing racing filter. It is supposed to flow 15 gpm and is full flow.
- If you look at the data I posted a while back comparing the Canton and the 1042 filters, there was not much difference between the 2 for pressure drop. So that was interesting.
- The Accusump (and pressure switch) is located post oil filter so it sees approx. a 10 psi drop compared to the pump pressure pre-filter (sometimes more under load).

- So if you look at the PCA 3rd session, the Min pump pressure was 52 psi. That would mean about 42 psi at the pressure switch, which is not low enough (35 psi) to open the Accusump. That's why it did not open during the entire session. Why? Not sure, but maybe the fresh oil made a difference, and also the increased air pre-load could be a part of it as well, contributing to an increase in oil sump level. If you look at the NASA session 3rd data, the Accusump opened 16 times during those 3 laps...
- No I did not see any evidence of oil depletion that would be shown by a substantial air pressure drop in the Accusump. It did not go below 51 psi, indicating about 2/3 of a quart remaining at worse.
- I think that if you're going to put an Accusump, you need a check valve AND/OR an oil filter that has an anti-drainback valve. With the racing filter, it does not have one, but my system does have a check valve to reduce back flow to the pump.

ah, sorry - you are already on that and i missed your filter comparison post. my bad. ok, so flow looks like ...

oil pump - avg 64 - remote filter - accusump insertion avg 58 - way down the line to the heads avg 34

so actually not much drop across the filter then. and it is tiny (8 micron) filter w/o bypass so no issues there.

i agree i am seeing little need for the pressure switch. my triumph gt6 race car has an accusump with just manual valve and seems to work fine. also, a caveat to those installing an accusump without a remote filter - with just a sandwich plate to add the accusump, i think it inserts before the filter (pls correct if i am wrong) so average pressures would be in the 60's and not the 50's which might affect choise of pressure switch if going in that direction?

The moroso sandwich puts the accusump after the filter but the canton and others i have seen put it before the filter. I thought after would be better to get any possible benefit from the anti drain feature of the filter, if it had one.

Yes, it looks like the Canton Racing sandwich plate feeds the Accusump (or oil cooler) pre-filter, so the pressures would be higher and you might need a higher setting pressure switch. When I talked to Canton, he mentioned that it would be better to have filtered oil going into the Accusump accumulator. Not to mention what Steved0x said about the benefits of the anti-drainback if you don't use a check valve. The issue I had when deciding to go with a remote filter base was two-fold: not enough room for a 1042 with a sandwich plate (too low), and more ports available to install pressure sensors with remote base (more flexibility). I think TuneRS now has a really nice remote take off plate that is low profile that integrates a backflow preventer.

This is an interesting discussion. I took my Accusump out a couple years ago. If anyone is interested in a setup, I'll let it go cheap. Just pm me.

Just sent you a PM.

Gang,

I was at NASA Bondurant last weekend and I logged the oil pressure data while using the Accusump pressure switch bypass, effectively running the valve open all the time when bypass is ON.

It is a very short 1 mile track with almost constant turns, and pretty slow overall. Last time I was there, the Accusump was triggering often.

Here's an updated summary:

http://986forum.com/forums/uploads02...1543200197.jpg

For session 1, I did not engage the bypass switch, just leaving it in standard pressure switch mode. It only triggered once. For sessions 2 and 3, I turned ON the bypass switch, keeping the valve open. Although the temps were warmer than session 1, I did not see any significant difference on the Valve Cover oil pressure minimums, with a 4 psi difference (31-27) between sessions 1 and 3 with bypass ON being better. This comes at the expense of a somewhat higher oil volume depletion in the Accusump, indicated by lower minimums/maximums air side pressures when the bypass is ON. This means there is more oil in the sump/in circulation in the engine. This setup is working well for me so far, but I can't yet conclude that the bypass switch ON has a significant effect on reducing oil pressure dips (starvation). Will need more data.

What I will do for the next event is reduce the total oil volume so that, at 80 psi air side pressure, the dash level indicator shows full and not 1 bar above as I had setup for the previous events. My suspicion is that the extra volume is contributing for the Accusump not triggering as often, as well as possibly the air temps being cooler. I also believe that the higher air side preload (15 psi vs 7 psi originally) is helping.

Another update with the most recent data from AMP with PCA this last Saturday.
It was a spectacular day to be at the track, great weather, air temp 65-70F, only a few cars in DE4, so a lot of open track!

Here's a link to the first 15 minutes of session 3, with data overlay showing the oil and accusump pressures. I had the by-pass switch turned ON for this session. This basically bypassed the pressure switch and kept the solenoid valve open.

https://youtu.be/-pKNVFNYCgE

Here's the updated data summary that includes the 4 sessions last Saturday:
Something went wrong for session 2 as indicated by negative pressures.

http://986forum.com/forums/uploads02...1543981522.jpg

The oil pressure during session 3 was rock solid. I am sold on the Accusump by-pass mod. I think this is a configuration that can be used for pre-oiling as well as open valve for track usage. I also believe the 15 psi Accusump air side preload is more effective than the recommended 7-10 psi. One other thing I'm doing is keeping the oil level slightly above the max line on both the dip stick and the electronic gauge. No issues with AOS.

I think you have a good combo:

Electronic pressure switch, which can hold the oil and then be released for pre-oiling, and also a way to bypass that, so it is always open, for when you are on the track. Combined with the higher starting air pressure, the accusump has more "power" to buffer the pressure fluctuations.

What Pre Pressure are you using in your Accusump? Gauge pressure.

Hey there, if you mean air preload pressure, then I use 15 psi now. Used to go with 7 psi but found that 15 psi works better.

This is all very helpful! Im considering adding Accusump to my 986S for track duty.

Also trying to reduce weight at the same time. Do you have any data to suggest that the 2qt is the best size, or would the 1qt system also cover the vast majority of the needs?

The charts are low enough resolution that I cannot tell if it appears the Accusump is running near the end of its capacity when discharging.

Thanks for any insights you can offer!

why does the voltage across the solenoid drop slowly?? I would assume it is in either an on or off position. (high volt or low volt)

Insights appreciated.

Great data above AZ986S. I installed of the accusump on my '01 986 S, in the tunnel, it fits well and seems to be the most logical location.

Here is a video of the results on the track with track tires. I run my oil level about half way between low and full, with this set up I get an accusump dump on almost every corner and even under heavy breaking. Based on the video there are even a few longer corners where the accusump runs dry. Running Mobil 1 0W-40, BTW. Accusump has a 35PSI valve with 10 psi of pre-pressure in the air chamber.

I also run into very low oil pressure at idle post track sessions, i.e 5-7 PSI at idle and 250 F oil temp.

Conclusion: If you're tracking a 986 or 996, strongly consider an Accusump or deeper oil pan, you'll need it.

Video Link - https://youtu.be/lp-PJr1aPtA

I autocross my car, and am trying to decide if I need a Deep Sump, an Accusump, or both!

I am leaning toward Yes Accusump, no deep sump, but would love to get the input of others. If both presents a large advantage, I am definitely open to that configuration. I already have the X-51 baffle setup with the stock oil pan.

Silber

Another question that occurs to me, is if you run the accusump all the time, without a pressure switch, how do you prevent the crankcase from overflowing into the AOS and intake at idle?

Hey Silber,

It's been a while since I've posted here, but rest assured all is well!

To answer your question, there is a one-way valve (check valve) that allows the engine oil coming from the oil pump to enter the accusump, but ONLY when this engine oil pressure is greater than the oil pressure on the oil side in the accusump. So when you run with the accusump with the standard pressure switch mode (with electronic valve), the oil will release from the accusump into the engine oil path when the engine oil pressure is lower than the accusump oil pressure. This is only usually momentary (up to a few seconds), but then the engine oil pressure will recover and become greater than the accusump oil pressure as the engine RPMs increase, in effect "recharging" the accusump for the next corner. This is what SAVES your engine from oil starvation... So, in this case, the worst case scenario is coming off the track after a session, hot engine oil, low oil pressure at idle (lower than 35 psi) and so that would dump maybe 1 quart at most into the engine and into the sump. Hence why you need to set you normal oil level lower than max. I also just switch the Accusump Electronic valve to OFF coming off the track after a session so that the accusump is fully recharged, and I only turn it ON when I am on my way onto the track, not at idle.

OK, so what I found with data over a couple years now is this is still not a perfect setup to prevent oil starvation (but better than no protection). There is a time lag when using the pressure switch and electronic solenoid valve, and that lag even if it is 500 milliseconds, can still add up to some engine damage over time. So what I did in my car was add a switch to "bypass" the pressure switch and effectively turn ON and keep ON the solenoid valve when on the track. What this does is it simulates a mechanical valve and virtually eliminates any time lag. I've had this setup for 3 years now and 40+ events driven hard on the same engine, using Mobil1 15W50. Stock AOS with X-51 baffle system. No oil consumption. The engine gets run hard, but I rarely redline it, preferring to shift around 6,500-6,800 RPM.

So I would say it has had a positive impact on reducing oil starvation and extending the life on this 3.2 engine, considering that I had the previous engine for only 14 events prior to it failing.

Anyone want to buy a complete, ready to install Accusump setup for a Boxster? Was mounted in the trunk in my car by the PO, was only used for about 1 year and 1-2 races, then removed. Includes custom hoses, oil filter adapter, electronic valve, mounting brackets, and all wiring needed. Asking $500 shipped to CONUS - OBO. PM me if interested.

Here is a pic.

http://986forum.com/forums/uploads02...1638798400.jpg