Actually I wanted higher and more constant oil pressure, because the factory two coolers RX-8 system does not provide - according to OC's thermostats opening-closing rate -,the reference 50,7 psi oil pressure at 3000 rpm with 30w oils, even well under 212 F oil temps. The other problem is that the oil pressure isn't increasing enough as the rpm's get higher. It is far away from the old +10PSI/1000 rpm rule.

Firstly I modded the regulators ( like Mazmart ). The PSI numbers was higher after this mod, at least it reached the 50 PSI at 3000rpm, but usually between 176-194 F oil temp ("the OC thermostats are working"), the pressure hardly got higher than about 58 PSI, even at 6-7000 rpms. So this mod did not solve the problem, but definitely helped a lot.

We all knows that the factory oil cooling system is very restrictive against oil flow, so it decreases the pressure numbers. Anyway I did not thought that it is restrictive so much.

It seems that the only way to decrease the flow resistance is using a simplier (shorter, higher diameter, not 90 degree bends…) cooling system. So I did it. I used 310mm windth 34 row oil cooler, and a high diameter 176F flow control thermostat, with -12UNF connects.
Now the pressure numbers are much higher at low rpms, and there are enough oil at the bearings on higher rpms. The oil temp hardly gets above 194F, it is usually under 176F, with opened bumper front grille.

 

did you try the larger oil cooler steel braided lines first? It looks like thats what you have on your single large cooler. Also do you plan to FI because if so did you account for mounting an intercooler on top of that?

 

Sounds like you fixed something that wasn't broke. In radiator cooling efficiency, surface area is not everything, but does count alot. Your've decreased it significantly. Aside from having a fun project and decreasing the overall cooling capacity by feeding oil heated air to the radiator, what is the practical point?

 

The heating effect of the OC on the water radiator is about zero.
More pressure on the same temp (like earlier) = higher oil flow, which means better oil supply for the bearings etc.., that seems weak in the factory system mainly at high rpms.

 

good job and neat install.
You probably have researched this a lot so i will not go into the 20w/50, 10w/30 debate.
Its your car.
With a 20W/50 oil the pressures are good, but like you said --its a flow not a pressure problem.
I bet you saved a good bit of weight in doing this also?
One word of caution? I am unsure where you live but in the winter months be careful that the oil does not get hot enough/fast enough. 180-200F oil is a good thing imho. Anything lower--watch it for condensation etc.

Really neat install---i like the top mounts you made
OD

 

~75F ambient air >>>> ~200F water core >>>> significant cooling
~200F oil air >>>> ~200F water core >>>> zero cooling

Your mod covers about 1/2 the water radiator cooling area. Cooling, by definition, means removing heat, which isn't possible when the cooling air flow is the same temp as the 'to be cooled' material.....So explain again how that has an "about zero" effect?

 

Not to mention the turbulance caused by the air pressure sandwiched between the two rads. Air wouldn't flow freely from one rad to the next unless the fins are perfectly lined up.

 

Thanks OD! Yes, I'm sure that more amount 30w is better for the parts (and the engine, OMP..and everything) than less 50w at the same pressure, temp.
Weight saving is significant, that makes me happy too.

Caution: Yes, I'm a bit worriing about the too low oil temps when the weather will be cooler. Maybe the thermostat can handle the situation, but I will see. One thing is sure now the bumper grille is more opened than in the factory system.

Thanks again, I need every force! It is already the second version of the thermostat-cooler-pipe arrangement, but it seems to me the last.

 

Spin9k and paimon, You are both speculating and have no factual data to back any of your statements up. Plenty of guys have almost completely blocked the radiator with inter coolers and not had cooling issues. Some have blocked the radiator and had cooling issues, it all depends on many factors.

ayrton012,

It looks good man, nice choice of thermostat I will be changing my single cooler setup soon. Did you use the factory lines that go to the block?

This is mine after the initial installation.

 

Instead of my answer, here are the words from well known cooler and parts seller, and racing team:

Installing an oil cooler
In the case of the air to oil cooler, The oil cooler will only achieve re -
sults where a vol ume of air is pass ing through the fins. The amount
of heat dis si pated by ra di a tion is neg li gi ble. In prac tice the most
con ve nient po si tion for the oil cooler is in front of the wa ter ra di a tor
where a flow of air is guar an teed. Even in cases where the wa ter
cool ing is mar ginal, plac ing the cooler in this po si tion will have
hardly any ef fect on wa ter tem per a ture. The sheer vol ume of air
pass ing through the cooler en sures that the air is only heated a few
de grees; not enough to af fect the wa ter ra di a tor per for mance, and
as the oil cooler is a more ef fi cient de vice for ex tract ing heat from the
en gine, the over all ef fect is help ful. How ever, where wa ter cool ing is
mar ginal it is es sen tial that the oil cooler be placed against the wa ter
ra di a tor face, oth er wise warmer air leav ing the oil cooler will be -
come tur bu lent on meet ing air at am bi ent tem per a tures and will not
pass through the wa ter ra di a tor

 

More quote from the team:

How ever, where wa ter cool ing is
mar ginal it is es sen tial that the oil cooler be placed against the wa ter
ra di a tor face, oth er wise warmer air leav ing the oil cooler will be -
come tur bu lent on meet ing air at am bi ent tem per a tures and will not
pass through the wa ter ra di a tor. If plac ing of cooler and wa ter ra di a -
tor in close prox im ity is not pos si ble then a duct of thin alu minium
should be made to ex clude the am bi ent air. If space is not avail able
in front of the wa ter ra di a tor due to an elec tri cal fan for in stance, the
cooler may be mounted be hind the ra di a tor and will still work well for
the rea sons al ready given.

 

^ I'm not speculating. The Laws of Physics and Thermodynamics have not recently been put on hold. The "success" of projects like this (or blocking the radiator with intercoolers) really all boils down to (pun intended) what you are doing with the car. IOW driving around town, to work, etc. all this is really superfluous anyway, just a fun project, as the system is not stressed anyway and there is enough capacity in the system to overcome the additional heat this brings to the picture.

Start running WOT a lot, take it to a track, and testing would show the true answer, not just taking some temp measurements from driving around and saying it's so much better now.

 

FIXED:

Installing an oil cooler

In the case of the air to oil cooler, The oil cooler will only achieve results where a volume of air is passing through the fins. The amount of heat dissipated by radiation is negligible. In practice the most convenient position for the oil cooler is in front of the water radiator where a flow of air is guaranteed.

Even in cases where the water cooling is marginal, placing the cooler in this position will have hardly any effect on water temperature. The sheer volume of air passing through the cooler ensures that the air is only heated a few degrees; not enough to affect the water radiator performance, and as the oil cooler is a more efficient device for extracting heat from the engine, the over all effect is helpful.

However, where water cooling is marginal it is essential that the oil cooler be placed against the water radiator face, other wise warmer air leaving the oil cooler will become turbulent on meeting air at ambient temperatures and will not pass through the water radiator.

 

Although yes, given the options, using a duct or close proxy system is better, doesn't really mean that it actually "works". Depending on the oil radiator's fin pattern, and the water rad's pattern, a ton of turbulance will be created due to the wind shear created by the first rad, then the alternating "cuts" of the second rad. What this will cause is a differential in pressure between the freeflow air through the water cooler on the sides (where the oil cooler doesn't cover) and the turbulant air in the middle of the radiator. Speaking strictly from a wind resistance perspective, this will create a pretty bad frequency band across your radiator, which may lead to cracks in the water cooler. Again, this probably wont happen, but it is a possibility. Also, using an air duct would create just as much turbulance, as there will be a build up of pressure in the ductwork.

Mazda did it right by placing the water cooler and the oil cooler in separate places, allowing freeflow air to pass through each.

 

Yeah, I think in Texas on the track in 100+F temps is enough proof to me that cars with huge inter coolers in front of there radiators can still operate fine. Bottom line is that you don't know what effect this will have on his coolant temps, if it has any noticeable effect on cooling at all. The oil pressure increase to me is a huge benefit. No matter how high my oil temps get now, a minute on a straight away at 50+MPH will drop oil temps 30 degrees in almost no time at all. My Fluidyne unit is way more efficient than the two factory coolers.

Plus, he has a real oil thermostat, so no cold oil is flowing through the coolers and back into his engine. Before it would take 10 minutes or so to get the oil up to a reasonable temp. Ten minutes is a long time and most do not wait that long before getting on the road.

 

Thanks 9krpmrx8! I followed your threads about your system earlier. It forced me to do this mod! Yes the thermostat...like yours.

You see this pic that before the thermostat there are the factory rubber pipe with the reusable red colored connects. I cutted the rubber pipes and used this light alloy reusable connects so the lines to-from the block are the factory ones.

 

Yes, this was the main reason for this mod. Same oil pump, and higher pressure=flow on the same temp, with the same weight oil.

 

Good idea using the factory lines, you would have seen a slightly greater pressure increase with all new lines but your method is definitely the easier route to get a similar benefit. The factory lines are good, the only restriction I see is the hard line that goes along the block and I'm not sure that would even restrict oil that much in this situation since you have shortened the length of the system significantly and it's a lot less restrictive.

Good Job!!

 

^ didn't think we were primarily speaking of air to air intercoolers here 9krpmrx8. The OP is talking oil coolers, not air coolers. Oil has a much much higher heat content than air, and so heat extraction needs to be, and should be, much higher.

In an air-air intercooler, as long as you get the interface between radiators right, there would be a negligable effect, as you say. The amount of heat transfered out is not enough to matter. No need to get defensive.

 

Yes, that that hard line would be better not to be. Maybe later. I wanted as short as possible the system. Thanks again!

 

I have seen inter coolers, a trans cooler, oil cooler, and an ac condenser all stacked against against a radiator without issue on Jeeps (dodges do this too) in no air flow, 100F rock crawling situations. I was surprised but it worked. You can't just look at his setup and speculate without data. Plain and simple.

 

Thats all I was trying to really say here. Again, im not bashing, and im not saying that its a worthless mod. All I am saying is if you honestly take thermodynamics, physics, and fluid mechanics into effect, cooling *would* be hampered.

Like others have said, maybe it would only be significant when really beating the car for hours on end.

 

your are right in therory. if all the coolers could be spaced separatly then the cooling capacity would increase. However, the capacity he now has is more than adequete.
Heck i have 2 air/water coolers and a secondary radiator in front of my a/c condensor!
Nuts--what we have to do .
OD

 

Another consideration to make is the affect of flow rate on cooling rate. All other things being equal, higher flow rate will result in greater heat transfer.

You can never have too much flow.

 

From this aspect the only that is matter how much is the temperature of the cooler? No matter if it is an intercooler or oil cooler or water cooler. The air goes across the cooler, not the oil, water, or air...and I think an intercooler could be hotter than an oil cooler.