swirl pots

[The Radium King]

did a bit of searching but no luck - is there a definitive thread on swirl pot interchangeability? if there is I apologise in advance to anyone itching to type 'search! there are many threads on the subject!".

[jaykay]

....I searched way back. IIRC on renntech, or Planet I found a Cayman racer that had fitted the old style to help mitigate oil related engine failures. I also know a guy who used to campaign a Cayman all over The States and said he has run both styles but never let on which he found to be better.....I think he has blown more than 6 engines so other failure mode combinations are masking any potential oil problems

I have seen in the past that LN Engineering Site recommends the newer straight discharge style with their latest sump extension arrangements. There was no explaination as to why.

When i was tracking and deep sumped way back I wanted the old style separators returning oil under the windage tray where the pick sits. It seems there are now on top return arrangements; I will be honest and say they make no sense to me. Perhaps they return oil quicker and or reduce foaming.

[tommy583]

Oh I thought you were talking about some kind of fancy toilets

[jaykay]

Glad I could ........er ehhhm clear things up

[steved0x]

Originally Posted by jaykay

I have seen in the past that LN Engineering Site recommends the newer straight discharge style with their latest sump extension arrangements. There was no explaination as to why.

My understanding (from the LN information on that same page) is that the newer straight discharge style return the oil faster? It says "Lastly, we include 997 oil return tubes to ensure that oil being pumped back to the sump returns as quickly as possible to the lowered engine oil pickup." Maybe the new style is faster than the old style? (Oh I see that is what you speculated as well in the following sentences)

Originally Posted by jaykay

When i was tracking and deep sumped way back I wanted the old style separators returning oil under the windage tray where the pick sits. It seems there are now on top return arrangements; I will be honest and say they make no sense to me. Perhaps they return oil quicker and or reduce foaming.

I thought the outlet on the old style was above the plane of the windage tray, with only the bottom part hanging down below that plane? Did you add an extender to the outlet or am I remembering it wrong? (I did not measure, eyeball remembrances only... ) I have heard that some folks using the mantis sport with the old style swirl pots pound it with a hammer to clear the bottoms instead of cutting 2 holes. Sounds crazy to me

[The Radium King]

hmmm, so looking like these pieces only provide benefit with sump extensions which have windage trays and the need to return oil deeper to the lower side of the tray.

[Gilles]

I thought that the main purpose of the swirl pots was to remove the air/foam from the oil to (de-aerate..?), allowing the oil to reach the pan ready to lubricate..

[The Radium King]

Originally Posted by Gilles

I thought that the main purpose of the swirl pots was to remove the air/foam from the oil to (de-aerate..?), allowing the oil to reach the pan ready to lubricate..

agreed. was interested in the difference between the swirl pots used on the 9x6 vs those used on the 9x7, as some folks are putting the 9x7 swirl pots on their cars. ie, why they are better and if they are a direct swap (most of the folks making the change appear to be doing it in conjunction with a deep sump install).

[jaykay]

Some interesting reading from ye old days:

Good Question: Why did Porsche..

I feel like I need to drop my sump to see if my holes are big enough to actual ensure directt drainage down. One can see here where the tray and pots interfere.....the sump opening flange surface. The tray / flange surface appears to bisect the discharge nozzle diameters. Sadly I did not incorporate extenders.....will have to add them!

[The Radium King]

hmmm. that's what I was looking for - thank jaykay.

SO ... 987 is the only engine that looses the separator; 9x6 and 997 keep it. why the difference?!?!? a quick check of 987 vs 997 part numbers shows that the oil gallery is the same part number between the two (and a 996 part number so no change from the m96 engine) as are the baffle, pick-up tube and sump cover. oil pumps are the same 997 part number in both.

jaykay - you thought it might be due to CoG differences between mid- and rear-engine cars? no need to de-foam as there is less movement of the engine in a mid-engine car. well, a quick check of 987.2 dfi cars show that the oil separator is back, so perhaps a failed experiment by Porsche? methinks i'll keep my 986 parts in there for now.

[jaykay]

TRK if you have things open and sitting in front of you, you can have a look at what configuration would give the shortest return path to the pick up location under different sump conditions. Then there is deairation. With a windage tray in place, my eye and horse sense tell me the old style pots and extenders are the ticket. This will deliver oil more directly to the pick-up directly below the tray.

Yeah I was grasping for straws back then thinking about rear vs mid centrifugal effects. I think the 987 type returns were a band aid attempt to deal with larger displacement mid engine heat related engine failures coming from increased Cayman track time. From what I can see, I believe this design was definitely configured for no windage tray in place ( stock ).

If you have a look at GT4 front fender liners....they are cut wide open with only chicken wire mesh to protect the back of the rads. IIRC an portion of each side intake goes to engine cooling air flow. I believe the sump plate now has ribs for better heat transfer Measures to increase cooling for the larger 3.8 tucked in amidships rather than out over the rear axle.

Of course these are all armchair suppositions

...stay warm up there,

J

Edit: I have trolled around a bit.....it seems there are a multitude of Cayman guys that retro-fitted the the 996 pots. One would have to dig deeper to garner their experiences and results.

[911monty]

Hope I can throw something out there. There is the issue of discharging fluid under pressure directly into the area where a pump is taking suction from. This is not desirable due to fluid under pressure impacting surface which creates turbulence and mixing with air that can then be drawn into the suction of the pump causing cavitation. Typically you have a pump discharge into a baffled area where it quiets, de-airs then flows to the suction of the pump. The swirl pots may deaerate by slowing fluid flow before dumping into the sump. Are the 987 type deaeraters? . Either way it may be best to not have the discharge directly into the sump? If you had to I think you would at least want the fluid deaerated by the swirl pots. My 2 cents..

[Bebbetufs]

Sorry to resurrect an old thread. I just wanted to say how important it is NOT to extend the outlets of the swirl pots directly to the pickup. The swirl pots are not able to remove all the air sucked in by the scavenging pumps. The oil returned to the sump is full of tiny air bubbles. You do not want these anywhere near the pickup. I'm guessng this may be why the 997 exit the oil at the highest point in the sump so the oil can slosh down the walls letting the bubbles dissipate before filling up the sump.

In the 944 engines this is a thought to be a main reason for rod bearing failures as the oil is so close to the crank it is whipped into cream during hard breaking. Air is not very good for keeping mechanical parts separated.

This is also why I'm not completely sold on the horisontal baffle plate. It seems like an efficient way of trapping air bubbles as they dissipate from the oil. I don't know if they can escape freely without getting too close to the suction from the pickup. I guess it's not a problems since people have been logging oil pressure and found it to be stable with this plate.

[Gelbster]

It is good that ppl are questioning the physics of the sump kits.
TuneRs kit has the 997 swirl/pickup tubes. Originally they had the horizontal baffle in the wrong location.I had quite a debate with the manufacturer on this issue.Eventually they changed their Instructions and heavily redacted the on-line debate - which I am totally O.K. about.The objective was to fix what I claimed was a mistake and they did.
The oil-foaming is an important issue (imho)but seldom mentioned nor discussed except by a few. Not surprisingly, Jake has shared some useful insights on this issue.
One response is to use a specifically low-foam oil. Yes, it is available because some other high volume production engines have a oil-foaming problem.

[thstone]

The PedroSump/TuneRS Deep Sump comes with the 997 type swirl pots. They are directly interchangeable.

I also modified the horizontal baffle to work with the EBS X-51-style baffle.