Ok---so in summery?

IMHO---I repeat --IMHO --here is a list that I think has the most impact:
The MM water pump and thermostat is a GIVEN.

1- secondary radiator--add's coolant capacity, add's cooling surface area, can be placed into optimum air flow. Best to use this with MM water pump and thermostat? Best for hot climates?

2- upgraded radiator (certain ones--all do not work--stay away from the Kyroso?)--best to use again with MM water pump and thermostat--, adds coolant capacity, usually the core is thicker, watch fin count to insure air flow? best in moderate climates?

3- 70/30 coolant blend. Duh.

4- Barrel type thermostat--requires custom fitting and it eliminates the bypass system. It does help but is it worth it?

5- different ways of increasing flow through the oem radiator. sealing, removing stuff from the rear etc----pros and cons exist?

6- replacing coolant with Evans or other differant types of coolant. Doesnt solve high temps. It does solve boil overs etc. Most do not recommend this for a street driven car.

Agree that when coolant temps gets to 225F--then its too hot and measures need to be taken?

And one that has always had my personnel interest (and BMW is now doing in some models for 2011!) The electric water pump. This will be an up and coming thing--mark my words.
Huge advantages. No disadvantages if done properly IMHO.

Does that wrap it up?
OD

 

No mention of lowering oil temps to affect coolant temps. I will add the secondary radiator soon and I wonder if the MM water pump is really that much better than the updated factory pump?

 

there's an updated factory pump ?

 

Yes the impeller is redesigned and plastic I believe on the updated one. All of the remans received the updated water pump supposedly.

 

I dont think you want to go lower then 210-220 for oil temps. However if the oil cooling capacity is lacking, I think you would be causing the cooling system to work a little harder then it should.

A secondary radiator sounds like a great option for FI and track cars that still need better cooling after the other upgrades.

 

I agree--do not run the oil too cool. I think 180-190F is ok?
The single oil cooler imho has advantages of quicker warm up(important)and less restriction (so better flow), but dont overcool the oil. That can cause among other things more condensation to occur in the system. White milky stuff. That stuff is NOT good to have.
9K has all that under control.
OD

 

180-190 around town is fine, but they should come up to 210 on the track or during extended WOT runs, atleast according to an article in grassroots mag and some things other knowledgable forum members have said.

 

Yeah I run about 190F oil temp if I am tooling around town taking it easy. But the minute I mash the pedal for more than a few seconds the oil temps average around 200-210F. In bumper to bumper traffic (very rare for me) my temps can get to the 230-240F range.

What is crazy is that it has been so hot lately that even after my car has sat for 9 hours during the day, my oil temps have still been 105-108F when I get in her to start her up after work.

 

What temps were you seeing before the single cooler mod? For what you say it looks like it is a not so efficient mod. 210 if you just mash the pedal for more than a few second sucks.

 

Prior to the mod, oil temps were about the same average on the street but it took forever for the oil to get up temp and once it did get hot (240F+ range) on the track it took forever for the oil temps to come down. With the Fluidyne unit I only need a few seconds at speed to drop oil temps 20-30 degrees. Also, keep in mind the ambient temp here in the summer is 100F+.

200-210F average when driving hard (with air flow) is an ideal temperature range IMO. But yes oil temps rise quickly when the revs increase. But a good fully synthetic should be able to handle 300F and in a response to an email I sent to Mobil1 the rep said anything above 160F is fine.

I am running Rotella T6 5W-40 now. as a rule I don't rev past 4,000RPMS until my oil temp exceeds 170-180F.

 

210 is a bit too high actually for both the water and the coolant. In the post where I stated my temps you can see what I usually see as oil and coolant temps and the mods i have. We live in 2 environments with similar ambient temps, it is very humid here though.

Mobil 1 is the worst oil you can put in a rotary unless you have a sohn adapter. It mixes with fuel like crap so i hope that that mail was just informative
Also keep in mind that if an Oil can still lubricate at 300F it doesn't mean that the metals our engine is made of can stand that temperatures, plus the oil life at that temperature is pretty damn short

 

For example:

We do Canyon runs that cover about 300 miles. That 300 miles consists of blind switchbacks, chicanes, huge elevation changes, tight turns, and some decent straight and slight curves. In this Texas heat things heat up very fast, the pavement is very hot and we only stop every couple of hours.

This environment is a lot tougher on the car than a track day is. You spend a lot of times in the higher RPM at fairly low speeds and you have warm air from the car in front of you to cool off. So if your temps get to the limit you have no choice but to back off until your car cools off. With my oil cooler mod I don't have to back off when others do and when I get my secondary radiator in, I will have even more room to play with in terms of "fun time",

 

I guess we can agree to disagree

210F is perfect for oil temps and many track cars see oil temps in the range of 250F. There is actually an article about this in the latest issue of Grassroots motorsports about how extra HP can be had in the 205-210F oil temp range.

I do have a SOHN adapter but I don't run Mobil1 now. But I did for a few oil change cycles and my used oil analysis from Blackstone showed that it performed just fine (significantly better than the famed GC 0W-30). I only switched because the Rotella performs great as well and is much cheaper to purchase than the Mobil1 0W-40 I was running.

And for me oil life is not a big deal, I change my oil before it hits 3,000 miles and if I am going to do a track day or canyon I usually change the oil right before or after the run just for the peace of mind. I bought a large amount of 09' filters from Mazmart and I always keep a gallon of Rotella on hand so I can change it as I please.

 

Mobil1 is fine in the engine but sucks in the housings so I second your oil analysis
Did grassroot SPECIFICALLY mention rotary engines? There are areas where we don't have to care about it being different (usually where it is about pumping air) and areas where unfortunately the standard otto cycle data doesn't apply.
Cooling is fundamental and i wouldn't like seeing oil temperatures over 100°C (a tad over 210f) if not for very short periods of time and at high rpms\loads.
What worries me is your bumber to bumper traffic temperature. Way too high.
That may be because of the oil cooler design performing poorly in such applications. It may have more total cooling area\surface but the oil spends actually more time moving through the 2 oil coolers and their "restrictive" path\system.
If i were to daily drive the rx8 on the streets\in traffic i wouldn't consider this mod to be that great

This also drives straight to my proposal a couple of posts back. Following a "method" when discussing mods makes a huge difference and helps others making good choices for their application-

I may sound harsh writing but I actually am not, just trying to go through a path instead of going in circles

 

Some articals about oil in rotary engines from racing beat.
Oil tips including temp and pressure: https://www.racingbeat.com/Tech/Tech.Oil.1.htm
Oil filters and OMP: https://www.racingbeat.com/Tech/Tech.Oil.2.htm
Synthetic oils : https://www.racingbeat.com/Tech/Tech.Oil.3.htm

They say oil should not enter the engine above 205 deg, I take that as meaning that the oil from the oil cooler. So I measure oil temp at the oil filter housing and I dont believe that oil temp is directly from the cooler, its a mix if I understand it correclt. Please correct me if I am wrong.

Racing beat likes using sythetics and they like premixing. Both increase HP and synthetics decrease temps. They dont mention the OMP and synthetics but I think we are all on the same page. Dont use synthetics if you are using the OMP without a sohn. I premix and use the sohn on the track. Best of both worlds in my opinion.

Some more info from royal purpal. http://royalpurple.com/faqs-rotary.html
They say their oil can be used with the stock OMP but its best to premix or use a sohn (did not say it but implied).

Lots of reading. Have fun. A lot of this info is outside of the cooling topic, so try to limit the conversation to cooling.

 

Incorrect. The right sentence would be: don't use synthetics that don't mix well with fuel in the housings.
At least Valvoline, Royal purple and redline mix well with fuel so yep let's keep this about cooling and don't steer the readers towards not completely correct knowledge.

 

Correct, that is more accurate. But synthetics are a little expensive to inject with the OMP and burn up. Better to use a sohn, premix or both.

 

Yeah I rarely drive in traffic, but last month I did get caught in bumper to bumper traffic coming back from a car show and the temps got really high. But it didn't overheat and there was no air flow. And of course, making more power makes the car run hot

Also, I don't have any data to back it up but I think low oil pressure and high oil temps aided in my previous motors dieing. When this engine dies (hopefully long from now) I will finally have a chance to find out exactly what killed it.

 

Oh, and I run 2 stroke in my SOHN and in my gas. I have many logs and I can see the temp averages and how they are during high stress situations and I don't regret my single cooler mod at all but when I redo it and if I was to make a recommendation, I would mount the largest most efficient cooler I could find in one of the factory oil cooler locations. This would simplify the hoses and get great air flow.

 

You should also note that traffic driving means high loads\low speeds. Couple that to the reduced airflow and you have the reason why all the engines i unluckily had to take down had worn bearings after less than 60.000miles. Traffic in italy sucks that much!
As I wrote elsewhere my car runs ok with the mods I have listed so i don't see a point in removing the 2 coolers and puttng just one larger model at least in my case.

Is the single oil cooler a solution? Maybe, for some uses.
Is it worth a shot (parts\labor)? Unlikely for the average guy. Just cut the back oil vents and put a real front grille. Cost? 20$ or so!

I'm stressing hard on making this thread tidy i know but any other way of discussing "cooling" mods without specifing the environment they're used in makes all we write just a useless bar talk and wtf i don't see any beers here!

 

Oh, and on a side note, I just picked up my bosses 2011 Porsche Cayanne from the dealer for him and on the drive back to the office (no traffic, all highway) the oil temp was 225F.

 

I will running a fluidyne therm-HX oil cooler, in the left side stock location and using the right side for a second radiator. Its the db-30416 which is the smallest of the series but any bigger and I am not sure it will fit. Over all I think I will have much lower temps on the track, both oil and coolant. it still holds 1.15 QTS of oil which should be as much or more then the 2 stock coolers.

Fluidyne has a taller and thicker unit the db-304616 and 40617 (double pass) that hold 1.6 qts oil. If that unit would fit it would be far supperior to the stock units in every way.

For someone in a hot climate and who does a lot of city driving or low speed track driving, adding a fan would be a big help. For high speed track conditions the fans will hurt air flow.

I have modified the vents behind my coolers and it does help, I also have the mazdaspeed bumper which has larger openings and grills to protect the coolers.

 

Do you think it's high heat or low pressure that caused those failures ? Just wondering aloud here if JDM 8s with only 1 cooler and perhaps higher oil pressure is a better setup ....

 

I have no idea but I really love the e-shaft bypass pellet mod (rear bearing wear is pretty common here. Short commutes ) and the increased oil pressure surely helps but i don't have the time and the money to see how those mods would affect an engine that does that sad kind of life
A single oil cooler system only sees a slightly higher pressure though, with the pressure regulator it jumps to above 7bar FAST!
Keep in mind that the bearings are still capable of working and that the problem is carbon build-up\sticky or worn seals but their wear is accelerated.
We're going off-topic though, if you want shoot me a pm

 

I often wonder how much the AC condenser reduces flow. But I'm not about to ditch my AC