M96 m97 scavenge pump filter or screen

I want to put a filter or at least a screen between the inlets of my Porsche 996 oil scavenge pump to protect them from debree. They are available for external dry sump systems - where the screens are simply pipe/ hose fittings that screw into the intake ports of the pan, and range from $25-50 or so. Obviously, We don't have externally-run hoses for our scavenge systems, but maybe something could be made that could fit into our head's passages for the oil intake.. If not, anyone interested in buying them if new ones were to be developed? Example: http://www.speedwaymotors.com/Shop/O...creens/15.html

Just curious, where do you plan to put the filters and why you want to specifically protect those pumps? The inlets of the pumps are retangular ports and the pick up points are at the bottom of the heads that will require at least cam cover removal to access? If there are large debris for them to pick up, the engine should probably be rebuilt or disassembled anyway?

If you envision having enough debris in the engine to necessitate the screens, don't you also run the risk of clogging those screens with the debris you're trying to catch? I know filtering stuff from the oil is crucial, but is it more crucial than ensuring oil is delivered as long as possible if something unexpected does wind up circulating in your engine?

From the number of examples of damaged scavenge pumps Jake has seen & replaced, he must surely have considered this ? What mesh size would you specify and why?

There is a filtration rule of thumb that says you should filter to 1/3 of the smallest dimension you are protecting. Using this, I would say you would have to remove particles 1/3 of the pump internal clearance to ensure it isn't damaged/scored.

great, thanks rh66

Was thinking something like these scavenge filters.. But to fit our application. http://www.petersonfluidsys.com/filters.html

One of LN's articles about the M96's 'integrated dry sump' states that "the scavenge pumps and associated oil return passages (and de-foamers) cannot return and process the oil fast enough" to prevent oil starvation. Is it possible (advisable) to add a filter with the appropriate filtration properties that does not interfere with/degrade the performance of the oiling system?

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Smart comment. Well done for finding the credible insight. I fitted M97 de-foamers to my M96 and although they are a different design I do not recall observing any feature that would improve oil flow compared to the originals.So a mesh filter in that part of the circuit may impose a significant(?) reduction i flow - even for normal fast road applications. Does the 9A1 address this issue ?

The bank 2 987 Scavenge pumps have screens. They are only there because that pump doubles as a vacuum pump for the power brakes. If it fails, then so do the power brakes. That screen does;t do much when something else fails.. Why? It just clogs and the pump seizes from oil starvation. The real cure here is to better filter the primary oil, and ultimately to omit the things that shed the debris in the first place. I have fitted screens in the past, but it did nothing, and was a waste of effort.

So it sounds like a simple coarse screen filter would not be very helpful. It fills up too quickly and doesn't filter out fine enough particles. For typical oil pump gear tolerances and filtering rules of thumb like those mention put filtering requirements probably in the 50 or so micron neighborhood. There are stainless steel mesh filter screens available at that size, but at cold oil temperatures, oil viscosity would become too thick, so a bypass with a coarser filter (i.e. Screen), would be needed when the suction pressure gets too high (i.e. When the engine oil is cold). After further research myself, there also isn't a lot of suction pressure available in the front of pumps (that's probably why we don't see finer mesh oil screens on any oil pump pickups - they are all coarse). I think we can call the finer mesh idea not very feasible one, and a coarse screen, as been mentioned, would probably be fine from a pressure drop standpoint, but won't fully protect the scavenge pumps.