Well some of us will be the Guinea Pigs. I just don't see how more pressure and temperature management could be a bad thing if monitored closely. I may be simplifying things for my own comfort but It seems pretty obvious why the changes to the Series II were made.

 

This is of course a valid, and important, question. Usually, when you increase the flow through a cooler, you improve the heat extraction. But, I suspect there is some kind of curve involved, that describes heat transfer as a function of flow rate, and, at some point, it's possible heat transfer would decrease with an increase in flow (perhaps at full turbulent?).

Did the oil coolers change for the S2?

 

I think we are seeking more pressure too, not only flow. I say this because the S1 Renesis has the lowest oil pressure in the rotary history (average and max./rpm), and has the most engine's bearing problem.
The other thing why I say we need more pressure, that the S1 Renesis does not take the min 10PSI oil pressure/1000rpm combustion engine's bearing rule (90PSI-9000rpm).

 

We're certainly not going to get anywhere without someone stepping up to experiment. I won't argue with that one. However, experimentation and acquiring results requires responsibility with how those results are gotten. As I said, a peeve of mine is boasting facts without any backup data. Provided there is data to show X hypothesis then I'm on board.

I disagree, however, that we know for sure why the re-designs on the S2 were made. Mazda is experiencing seal failures not bearing failures. If the oil system is redesigned it would be to provide better OMP delivery. They did that. Pressure increases and other redesigns could serve a different purpose.

Increasing flow will improve heat extraction only to a point. As I mentioned previously, talk to any hot rod owners about removing thermostats from their cars. You can't do it because the water rushes through the radiator and doesn't shed enough heat. Oil gives up heat slowly so spending a bit of time in the cooler is required.

Thinner viscosity oil sheds heat easier because of it's physical property and because of the lower amount of surface friction it creates less heat.

You can increase the heat of a liquid by pressurizing it but since you cannot compress liquid (within reason) you cannot increase it's temperature by much unless extreme pressure is created.

The one fact everyone is forgetting is you only need enough pressure to get oil into the bearing at a given RPM. That's it! Any extra pressure is just a waste and the pressure of the oil exiting the bearing is irrelevant. Unless it can be demonstrated that oil isn't making it into the bearing at high rpms then that reasoning is out the door.

Increased flow is important because flow=lubrication.

Let's be careful what dots we are connecting here. I've got an army of people over in the 5w-30 thread that swear up and down the bearing wear is viscosity based. Just because two things occur at the same time doesn't mean one caused the other.

Currently I see a max oil pressure of about 80psi at 9,500 rpms. It maxes out before then but that's what my peak shows on my gauge. Provided oil is getting into the bearing I don't see how there could be major surface contact because of the large hydrodynamic wedge being created.

For the same reason your car will hydroplane at 80mph but won't at 30mph. You get going fast enough the tire will ride over the surface of the water. Bearings are no different with oil.

The truth is that higher pressures might not be necessary. Unless an engineer can tell us why the system was redesigned that way it's anyone's guess.

I don't think any harm will occur from this provided the temperatures don't spike during the summer. I just want to make sure if we declare this a fix to some oil issue that we actually have hard data to support it.

 

I cant believe we keep repeating the same subject matter...

Sorry Flash, but you keep disagreeing on information because you don't like what others are saying or doing, this has been done to DEATH...

I will repeat some FACTS..

The ENGINE internals between an S1 and S2 are the same...Seals, Bearings, springs.
What did change was the Oil Pump and EMOP System and Mazda removed the Rear Oil Pan By Pass Valve and replaced that with a front OCV valve.

Fact, the OIL Pressure has increased on S2, at the Rear Oil Intake area where Mazda officially measures engine Oil Pressure.

72.5 PSI @ 3000 RPM S2 compared to 50.8 PSI (5W20 Oil)
40.0 PSI @ 1500 RPM S2, some were seeing around 25-28 PSI.

The Renny 1 does have a lower Oil Pressure than any other rotary made, is this because of 5W20 oil, oil coolers being restrictive and with many long Oil Lines? (a single Oil Cooler has shown to increase OIL Pressure...FACT), just like the FC RX-7....funny that, same pump and valve parts as an S1.

While I understand your views concerning Summer temps, IMO it has been shown that with a few small cheap mods you can bring your S1 RX-8 up to spec of previous rotaries where this bearing wear was not evident at such a low mileage.

Everything I have read, heard from others and other re-builders points to the same conclusions, better Oil Flow (done by increased Oil Pressure) is beneficial for the Renny 1.

Just remember too, back in the days of 20W50, bearing wear at 50,000 miles was unseen, unheard of...imagine the Oil Pressure with this thick "crappy" oil?
I would sell bearings for engines that had done 3 time the distance of renny 1.

 

Flash --you ask good questions and make some good points.
I would like to offer some clarification of my thoughts.
1- bearing wear doesnt have anything to do with the bypass mod. As it has been said -proper viscosity of oil (proper oil film strengh) is the key to prevent premature bearing wear
increased oil flow around the bearing housings cannot hurt.
2- higher pressures are maybe not necessary, but i firmly believe that higher oil FLOW is. And the only way to get it is to up the pressure without tearing the engine apart. I believe that removing more internal heat and possibility improving the dynamic balance of the rotors is needed.
3- the oil flow through the coolers is a non issue. They have a bypass of their own which is temperature regulated and the coolers are a plate type which also is not known for fast flow rates. It WILL be something to watch as the warmer months get closer.
4- i also think the 04 oil filer is too restrictive on the cold start up and has too low of a by pass pressure with the heiver weight oils.

None of these mods will cause any damage to the engine and agreeded that a lot of the reasoning that I am using at present is based on lodgical thinking only. But more hard data is being discovered weekly. Nothing negative yet.
OD

 

I agree with a lot of what is stated above and honestly the only down side to my single cooler mod has been too much cooling of the oil during this unusual cold snap we have been seeing here in San Antonio. The oil warms up much faster but, only averages at about 162-165 at cruising speeds on the highway. In traffic it is between 180F-190F but I don't often drive in traffic so I find myself driving hard to assure the bad stuff gets burned off.

I am currently working on a solution to block the cooler.

 

Actually, I think only one regular poster on this thread seems to be forgetting this.

 

Quote from Mobil1 about my 0W-40.

Now mind you, my measurements of 163-165F are being taken at the return line so I'm sure it heats up plenty once it enters the engine so maybe 163-165F at cruising speeds is okay.

 

I'm sorry this is not correct and is a pet peeve of mine. This rumor was started because people removed the thermostat to gain flow (because they had an over heating problem) and it only aggravated the problem. The real reason they ran into problems is that removing the thermostat also removes the restriction that builds pressure in the engine, so they gained flow, but reduced the boiling point of the coolant in the block.

There has been, and still is, the rumor that of the coolant flows too fast, it will not have time to pick up heat or time too cool off in the radiator. That is nonsense, as long as there is coolant contacting a surface, the rate of heat transfer will be the same. Coolant (or oil) that flows twice as fast also flows through the engine and cooler twice as often.

That said, there are minimum and maximum ideal flow speeds that are dictated by the need to prevent scale accumulation and turbulence, respectively. Also, the minimum flow velocity is partially determined by the need to get the coolant off the engine and into the radiator before it boils. But there is simply no upper speed at which the water or oil will cease to cool the engine. This is simple physics.

 

I reject your reality and physics and subject my own.

 

+1

 

Ash I'm sure you can understand how skeptical I am of some of the conclusions that have been reached in these various oil threads. Everyone has their own narrow point of view and mine happens to be my own car.

The fact in my case is according to conclusions on pressure, viscosity and in some cases oil type my engine should have died a horrible death a long time ago.

It's not that I don't "like" what others are saying. It's not an issue I'm emotionally attached to.

If I'm wrong, I'm wrong. However from where I am sitting I must be right about something. If people want to call then I'm fine with that and I'll happily stand corrected on any issues I realize I got wrong.

 

That's what I like about you Flash; you're intelligent, knowledgeable and humble enough to state when you may be wrong.

My knowledge on this topic is more than most but less than some. I always fall back on Rick's opinions regarding these things and his experience is vast between street and race applications and including V8 hot rods from before most of us were born. Rick also worked for Lockheed way back when doing hydraulics so he has a very good understanding of fluid flow and thermodynamics. When I quizzed him weeks ago about traits being observed and speculations including too little time in the coolers he laughed at me and said something about cars in the 50s and people removing thermostats causing cavitation but thinking it was due to the quicker flow. He mentioned that there was no connection to this situation. On Rails statement is closest to Rick's explanation.

Paul.

 

There's no such thing as too little time in the coolers, the system is a heat pump, so faster flow=more heat pumped from the engine to the coolers, the time in the coolers doesn't matter.

 

older than some but not all---now if Rick will let me play with that 409 chevy he has back there
you would see a grin on a mans face unlike any since Adam and Eve!
OD

 

I have been researching some things and I may bump up to a higher temp thermostat but I will wait until it warms up first. There does not appear to be any hard data as to what the oil temp range should be going in and coming out of the engine. I am actually thinking of installing a second oil temp gauge to the thermostat to see what the temps are coming out of the oil pump.

 

Thanks for the compliment Paul it's appreciated!

 

I call them like I see them. You're one of the class acts around here for sure.

Paul.

 

 

I like one in the oil pan.....it's the "soaked" temp of the oil......

The temp coming out of the coolers pre-motor is artificially low

Although really what is important is knowing what your oil temps are doing.....

 

I would have to imagine that the oil heats up more (and quicker) due potentially to the greater volume of oil being used to cool the rotor surfaces. The necessary amount of this cooling action is certainly questionable, and most likely reflects the type of use the engine will see. Higher load = higher temps.

I look at the mod this way: Most of us participating in this discussion use oil viscosities greater than xW-20, or even xW-30 for that matter. With the stock regulators, the system might prevent sufficient flow when using higher weight oils. The only way to prevent this is to modify these regulators to allow for higher pressure (and therefore, more flow with heavier oils).

As I've said before, I don't think these mods would substantially increase the pressure if xW-20 oil is used. Flash, since you're one of the very few people around here that use such oil, I would be VERY interested in seeing you results with this mod.

 

Olddragger mentioned that we are going to have a group install of the mazmart oil pressure modification kit. This will take place on Jan 23rd at my place. We will be collecting temp data at various RPM's/ambient temps compare before/after results. This should be interesting coming from multiple cars. We will be collecting results on garx8club.com but I will post them here as well.

 

Can't wait to see the data!