I'm with you and your thoughts mirror the reasons I started the thread. I'm also with you on the cost issue, but if you follow the cost argument further...what if the most important factor is driving style and the band aids actually do nothing to stabelize oil pressure and are purely there for as a comfort blanket and to fill vendor's pockets? If so we might as well just stop after doing all cooling mods (confirmed) and just drive...We keep the money for a future rebulid. Unless the mods add power of course.

The reason I'm sceptical to the accusump is that I have read, and I suspect, it simply has too much lag to fill in the pressure dips. Also, all air bubble sucked in by the pickup, (or from pump cavitation due to high RPMs?)is already in the systen when the pressure drops and the only way to purge it is via the bearings. As Chris says it may help for extreme cases where the pickup continues to suck air for a longer period, but that is not what is causing pressure dips. If you have lost pressure for that long you have also lost your engine, in my opinion.

When it comes to the dual scavenge pumps they may be needed for other issues.In more powerful high-revving engines where the oil flow is higher. Pooling, backpressure and areation from the moving valve train come to mind. Anyway, they surely can't hurt our engine.

Chris states that the X51 baffles may work in the rear mounted 911s, but if the logs show the same pressure dips as before the installation in a mid-mounted engine it clearly does not alleviate the specific problem of pressure drop spikes in our cars, at least not in the tested engine.

I understand your reasoning. Thanks.
I mainly run at Rudskogen. It is mostely accelerating rights and stop-go lefts. One of the rights is high speed and severely off camber. Top speed braking while turning right down the steep hill, then hard acceleration back up the hill and into the S's. This is where I expect the problem to be worst.

Nice mods and longevity.
Did you alter bearing clearances?
Would you mind sharing some of your logs?

Just to add my two cents.
80% of my business is to the racing crowd. I spend a lot of time talking to these guys and a lot of them are removing the accusump system because it isn't reliable (pressure switch)and is just dead weight. Of course you also have a bunch of people who swear by them. I'm leaning towards the useless side even though I have one in my car. I do like the ability to pre-lube though. That's when it's working at least. One thing they all agree on is the baffling in the oil pan. I think they all either use the X51, aftermarket or modify a factory pan.
Now when it comes to Cervelli's drysump system. It looks to be a wonderful system and has proven itself on the race track. Chris races in WRL and I don't believe he's blown a motor since installing his system. For those who don't know. Guys race for 8-24 hours in the WRL series. They beat the living tar out of these cars and 100 hours seems to be how long a motor last with them. Except Chris! Other race teams who compete with Chris are installing his system. It's not cheap but it might pay off in the long run. Here's the his website boxsterdrysump.wordpress.com or you can call him at 303-809-6173

Thanks for your opinion Woody. That's the final nail in the coffin for the accusump as far as I'm concerned. I have spoken to Chris, but I need to prioritize building a workshop. Maybe I'll buy his system in the not too distant future. In the meantime I hope my engine doesn't blow :D

Last summer I was hitting 205 on a regular basis. The track outings this year I saw my water temp at 185 to 190. My oil pressure was stable with a 15 PSI drop at 1.4 and 1.6 G's on the passenger side head, and no drop on the sump.

On a side note I added the engine bay switch at the same time so it is hard to say how much each helped.

My crank was balanced by a local service that builds 410 sprint engines. It was installed with stock Porsche bearings. My spinning weight is over 10 pounds less than stock.

I have shared videos with data on them but I don't know how to extract the data out of the video. I use a Garmin Virb XE with a Blu-tooth ODBII.

I don't know anything about the dry sump. The solenoid supplied with the accusump is crap, if you have one get rid of it. Find a online supplier of a 1/4 SS solenoid with a edpm diaphragm. Or else buy the manual operating kit.

My 2.5L Boxster logged 100+ track days, many at ACS Fontana which is known to kill dozens of 986 motors directly due to starvation. My brother and I ran nearly identical cars and both were regularly at the pointy end of the BSX time sheet. We never killed a motor.


There are lots of gizmos, gadgets, and methods to attempt to resolve this and I don't know any that are 100% effective. Here was our strategy with success over nearly 200 combined track days:

-Run NT-01 tires which are good track tires but generate less lateral G forces than the 40tw R-Comps.

- X-51 pan

- Castrol 5w40 oil changed every 6 months

- Make sure the oil level was exactly topped before every session at hi G tracks.

- Complete the banked sweeper at max speed and stay well away from the rev limit as we downshift for the next corner. The idea here is that after a banked sweeper, the pan is nearly dry from hi G cornering so we let the car idle under full braking to allow for some refill and only blip to 4k on downshift at the last possible moment. Pinging the rev limit with a nearly empty oil pan is the best way to cavitate the oil pickup and score the main bearings, killing a nice flat six motor.

I can't say these methods will work for everyone but they certainly were effective for us in BSX class.

I didn't say in my post above, I almost never go above 6500 RPM and typically shift around 6000-6200, exceptions are places like coming up to tower turn at Sebring (or other turns) where I don't really have time upshift because I would then immediately downshift so I wind it out a little but try never to go above 6500. I believe 6500 is the Rev limit on the 2.5 engine as well. It's just my philosophy. Am I losing time? Maybe... :)

Steve. What you are saying makes a lot of sense and is very interesting. Changing driving style and remaining quick may be the most efficient (and most complex) mod there is. I'll have to study a map of your track to learn more.

Unfortunately, a better solenoid won't help purge air that has already entered the pickup, which is what a pressure drop spike is. The air, or lack of oil, still has to pass by the bearings.

Hey Thstone, what brand is the horizontal baffle you have? Is it the LN Engineering one?

not to answer for him, but thats the TuneRS one, also known as Pedro's techno sump.

Yeah, then he added on the EBS X-51 baffle - more details in his thread (it is a big thread and many pictures are gone unfortunately due to photobucket...)

http://986forum.com/forums/boxster-racing-forum/46070-spec-boxster-build.html

I’ve been tracking my car (VIR) with R compounds for years and in addition to track events have been completing up to 20 autocrosses/year. It’s been living this life for 7 years or so, with no extra cooling or oil modifications (stock cooler, stock baffle etc) and I’ve been running Mobil one (not the best). It’s never had a problem, it’s outlived most of my buddy’s non-Porsche engines. I don’t have any “tricks” I redline it, don’t pay any mind to long sweepers and don’t have any oil gauges. VIR doesn’t have any banked corners per day but the car does pull 1.28 Gs in hog pen due to the elevation change. This all being said it’s probably on fire as we speak...better go check on it

@truegearhead. I suspect a lot of people do this and get away with it. People tend to talk about what goes wrong. If something works as expected they generally keep quiet, and nobody makes money on solutions that way either. Thanks. Then again, maybe your driving style is better for the engine. My plan for next season is to follow your example, with the exception that I do have some mods in place.

Just for kicks. Here's a nice rendering showing tank sloshing and the effect of baffles.

The rendering is of course not directly comparable to an engine as it does not take the insane tornado of windage and the unbelievably rapid flow of oil into account.

Considering the pickup would be in the middle it seems clear that baffle higth is important. The effect of the baffles depend on enough oil being returned to the central space as it is sucked dry by the pickup. At high RPM the oil pump moves about 1 qt (0.9L) pr. second or more. The amount of oil that can be returned at speed into the central space, and how aereated it is, becomes just as important, if not more, than how well the baffles can retain the oil.

Another potential problem could be that it seems like large pockets of air may be introduced as the oil rushes back to fill the empty side of the tank. This may be why some report more spiking in oil pressure with baffles.

Oil flow numbers.
964 - 65L per minute
930 3.3L - 100L per minute (high performance engines from this era uses larger bearing clearances to aid cooling, amongst other things. They need a higher weigth oil and larger flow to maintain the same pressure.
GT3 RS - 83L per minute (clearances are tighter in modern engines so a lower weight oil may be used. This lowers the need for flow and increases efficiency)
3.8 RSR - 57L per minute based on one persons dyno testing.
Source: http://forums.pelicanparts.com/porsche-911-technical-forum/193700-oil-pump-rating.html

Accusumps work great if you use the electric or manual valves. It's just 2 or 3 quarts of pressurized oil always available to feed the main bearings, pressurized by the oil pump. No lag, just pressurized oil. Stay away from the EPC set up where there is a pressure sensor that operates the solenoid...these have proven to be unreliable and can not deal with the wide range of oil pressures one sees on the track. The down side on this style is you need to remember to fill it EVERYTIME you turn the motor off and do it the same way each time so you can get consistent oil level readings.

So if I were to bypass the pressure switch that activates the EPC solenoid valve and just have a switch to turn it ON/OFF, would that work as well as the Electric Valve? I could easily test that just by some minor rewiring work, without physically removing the pressure switch. I like the EPC valve because it is a one-way valve and fills up the tank when turned off. I'm currently setting up my Race Capture and AnalogX system and hope to have oil pressure data at 2 locations: the standard bank 1 valve cover location, and also at the inlet of the remote oil filter (before the filter/cooler, after the oil pump). That is just across from where the Accusump feeds into the circuit (at the outlet of the remote oil filter). This should give me info on oil pump outlet pressure, and total pressure drop across the filter, cooler and engine bearings.