Ok, good to know.

Thank you.

The overall pressure, yes. But the element presents a resistance to flow. So there is more pressure on the input side than the exit side, otherwise there would be no reason for the oil to cross the barrier at all.

Yes, and that addresses the concern over filter bypass springs.

As to the second matter, IMO, whatever resistance to fluid flow the filter element may present is hardly a concern (and irrespective of oil viscosity) because the micron size the element is designed to capture is FAR larger than any oil molecule. Even if I am wrong my redneck reasoning tells me that, if viscosity mattered in this context, oil filters would be designed for use with certain viscosities and they would be listed on the oil filter. Then, we would have had a whole 'nother aspect of this oiling system debate we would have all been arguing about this entire time. :lol2:

Clearly, if the filter is clogged with dirt (which should never happen), the oil filter bypass will open. The molecule argument doesn't really apply to oil or to any liquid (the sole exception being superfluidic helium where quantum effects dominate), because there are inter-molecular attractive forces "binding" the molecules together. ( http://en.wikipedia.org/wiki/Van_der_Waals_force ). Those are the primary cause of viscosity. To pass a "hunk" of liquid through a solid grid, these bonds have to be broken temporarily in order for it to fit through which requires a source of energy - in this case the oil pump. Since (with the bypass closed), we're in a constant-volume mode which means the flow velocity is also constant across the filter element, the only manifestation of the energy absorption required is a drop in pressure across the membrane.

For normal circumstances, (warm motor oil), this pressure drop is likely faily minimal. For cold oil, likely not. Why? Temperature is motion. More heat means the molecules are moving faster than when they are cold. Roughly speaking, this means the inter-molecular force is reduced by the average distance between the molecules being greater and by that force becoming a smaller fraction of the total energy of the system. The result? The warm oil is easier to pass through the filter element and the resulting pressure drop is less.

By the way, air too is subject to these effects. Air is a gas or small molecules, but at atmospheric pressures, it behaves much like a liquid, in that there is a degree of stickiness between the molecules. ( http://en.wikipedia.org/wiki/Reynolds_number ) This is the primary reason why there is a pressure drop across an air filter. These effects only become unimportant at pressures < 0.0001 atmospheric or so.

<physics mode off!> :sadwavey:

Bottom line is I trust Mazda on this one. They didn't go through the trouble and expense of coming up with the high-bypass pressure Series II oil filter for the fun of it.

Yep, and looking inside the two filters you can see larger filter surface area. I have both, I bought a case of 09's filters Mazmart and I compared them when I bought them. I am actually out of them almost (that's what I get for donating them) :lol:, I need to reorder soon.

Wow. My head is spinning. I agree, I often wonder though if i am pushing too much pressure with the increase from going to a single cooler and the Mazmart mod.

http://www.flickr.com/photos/9krpmrx8/4452631871/http://www.flickr.com/photos/9krpmrx8/4452631871/ by http://www.flickr.com/people/9krpmrx8/, on Flickr

Your case is a bit of a mystery to me. I'm picturing the oil pump supplying oil to the coolers (with the front bypass teed into the circuit), with the oil then going through the engine, with the rear bypass teed into the circuit near the end of that journey, right before it drops into the oil pan. If the stock cooler setup represents a quite high resistance, then the pressure drops across it. Going to a less-resistant single cooler setup (like yours likely is) will then raise the downstream pressure by comparision. The Racing Beat rear bypass is set to 95 psi ( http://www.racingbeat.com/FRmazda4.htm ), less than the Mazmart one at ~120 psi. Presumably, replacing the Mazmart with the RB rear bypass would drop your readings. But also, removing one or two of the 3 washers installed as part of the Mazmart on the front bypass would also do the same thing. Which is better? I haven't a clue. Are the higher pressures you're seeing bad? I don't know that either. It would be interesting to see an rpm vs. pressure curve for a warmed-up Series II with 5W-20 and find out what the Mazda engineers think is good. Complicating all this are the variations between gauges and measuring points between different cars. :wallbash:

Thanks for giving my under-educated thoughts some consideration. I did think about the ramifications/validity of the inter-molecular forces but, since I am not formally educated on that matter (no pun intended) I didn't give it much creedence for most contexts. Since oiling system quality has not historically been much of a concern with rotaries (as I have been told, anyway) I think we may be contemplating navels and splitting hairs here, in a pragmatic sense, but I do agree that OEMs are always hard-pressed to make tangible changes in parts (as opposed to simply "updating" the part numbers) so Mazda probably had a completely valid reason for the oil filter change, but I am not in a position to speculate.

Oh, I think among "thoughful" people, it's little to do with under- or over- anything, but more of the fact we all have different tools in our individual toolboxes. Makes things fun. :grouphug:

It's threads like this that instill my belief that the R in RX represents a 5 letter word rather than 6 :cwm27:


.

I am actually going to get a high quality oil pressure gauge soon to rule out the prosport gauge readings. My lines are bigger going to my Fluidyne 28" cooler and the routing is much more direct. I was running Rotella T6 5W-40 but now I am back to Mobil1 0W-40.

Anyway, I will soon get some readings on a bone stock car running Mobil1 0W-40. I received these today and I will get some oil pressure reading beofre and after they are installed, and then I will also install the Mazmart RE oil pressure kit and then again take some readings. It will be interesting :) I love wrenching, :lol:

Racing Beat did their homework here I think. Everything looks top notch.

http://www.flickr.com/photos/9krpmrx8/5138379164/http://www.flickr.com/photos/9krpmrx8/5138379164/ by http://www.flickr.com/people/9krpmrx8/, on Flickr

http://www.flickr.com/photos/9krpmrx8/5138379642/http://www.flickr.com/photos/9krpmrx8/5138379642/ by http://www.flickr.com/people/9krpmrx8/, on Flickr

Don't forget the S2 does not have the (3648-14-250) Rear By Pass Valve that returns by pass oil directly into oil pan.

From what I can determine (from S2 factory Service Highlights) the S2 Oil Circuit includes supplying Oil directly from Oil Pump through OCV (Oil Control Valve) to the two external EMOP's mounted on top of engine.

Oil pressure is maintained between 7 and 20 PSI at EMOP's, the solenoid opens (one on each pump) and Oil is directed to the 6 Oil "Injection" Nozzles.

Excess or "return" oil goes from EMOP's directly to the Oil Filler Tube neck, then back into Oil Pan.
Not only is this used for Cleaning of EMOP's but also as a Oil Pressure releif...Possibly, though I can't be certain on the last part...it sort of takes place of the 3648-14-250 Rear BPV used in S1 and FC RX-7, RX-5's and late RX-4's.

9K, your system with the Mazmart By Pass mod is basically the FD RX-7 set up, minus the Turbo and slightly larger Oil Pump Rotor set.

Here is a pic of one of the S2 EMOP's, this supplies the original 4 Oil Rotor Housing Nozzle locations used in S1.

https://www.rx8club.com/attachment.p...4&d=1286917605

Ash, is the nozzle vent system still used with the S2?

Have you modified the ground circuit per Chickenwafer's findings from a couple years ago? Apparently, that helps gauge accuracy.

Interesting - must mean that they are limiting pressure from the "feed" end, rather than the "exit" end of the oil system as it goes through the engine itself. Plus there's only the one valve vs the 2 on the Series I. It's not clear to me why - with the OMP involved, there may be more than one reason for going this route.

I hate to throw a wrench into the working minds in here, but a question that kind of runs parallel with the talks of pressure and filtration...

Is the higher pressure system and different filter one of the main reasons why the use of filter relocation systems is often frowned upon when dealing with the S2's?

Yes I grounded the oil pressure sending unit at the oil filter adapter plate to the fire wall. On my temp gauge, I talked to the owner of Auber instruments and he recommended I wrap a wire around the sheathing of the coupler wire and send it to ground so I did this as well. He said this assures the best accuracy of the gauge.

No Charles, no vent hoses/pipes at all.

S2 Nozzles are S2 only...at this stage.

S2 Oil Nozzles
 

Here you go, this IS the S2 Oil Injection Nozzle (6 are used) and they are very expensive.

N3R1-14-631

Note the only outlet hole is to the side of the gold plated nozzle end...the hole is about 1.5mm.

Internally when you look down you can see a small mesh filter inside.

Other end is where the metal oil supply line Banjo and Bolt secures.

Sorry about PIC Quality..

https://www.rx8club.com/attachment.p...1&d=1288729717

https://www.rx8club.com/attachment.p...1&d=1288729717

I tried a couple different iterations of that with limited success. What worked was to run the ground wire from the sender all the way back to the gauge ground wire. Measuring around to several "ground" points on the car while it was running, I could detect (with a good Fluke DVM) measureable voltage differences. The technical phrase for that is "ground loop": { http://en.wikipedia.org/wiki/Ground_loop_(electricity) } On top of that, these voltage readings tended to be unstable as well. If the sender is grounded at one point and the gauge at another with a slightly different potential, there is current flow going through the gauge that is not going through the sender --> error in the gauge reading.

now that injector is the real deal--would love to see how it fits into the housing.
OD

^ what Ash said.