What are the expert opinions on disabling the oil cooler thermostat?

And how do you do it?

Also what does everyone think about paralell or series for dual stock oil coolers?

I know parallel is suposed to be better but anyone run both and notice any difference?

It seems like series might cool the oil better, even if it increases load on the oil pump.

Thanks

 

Alot of the guys on here are going to tell you that taking the oil cooler thermostat out is a bad idea because it cuases over cooling while warming up. Also if you search in the single turbo section for dual oil coolers you will see a few people that have done this, with pics.

 

Parallel is the way to go. In series you end up with a lower temperature differential from the air to the oil in the second cooler. That means its not working as efficiently for you and is just extra weight.

Oh, and keep the t-stat unless you're racing and can take the time to warm things up properly. We only take them out because I have never found out if they fail to the open or closed position and its always the cheap part that takes you out of a race.

 

No, it won't.

Radiators are all about deltaT- i.e., the temp difference of the air through the rad and the medium being cooled (in this case, the oil). The higher this disparity, the better.
Run in parallel, both radiators will exhibit the same deltaT; run in series the second rad is less efficient because it's getting oil already precooled by the first radiator.
*this assumes that pressure drop due to hose routing/fittings is equal between the two setups*

I've never actually plumbed a twin oil cooler setup but extensive experimentation with my water cooled computers confirms this opinion. Obviously there are differences- mainly in airflow, between the two (a car's airflow is extremely variable depending on speed where the PC's is steady, depending only on fan RPM) but I believe the basic physics are similar.

BTW...if you really want to lower oil temps, finding one larger cooler would trump plumbing two smaller coolers any day. It's the fittings and extra hose required to run two coolers that will kill you as they are a major source of pressure drop, typically more than the drop associated with the larger single cooling matrix.

 

Well, space and economy dictates that I use two factory oil coolers, I will have them roughly at the factory angle one in front of the other with about 6 inches separating them and some fresh air ducted to the rear cooler from below, but there is no way the rear cooler will get as much fresh air as the front cooler, which is why I am thinking series might be better, because they won't be getting the same amount of cooling air. I was thinking of having the oil go through the rear cooler first, then the front cooler and after to the pan.

Theory is great but its no substitute for experience,.

Does anyone have any experience with running factory coolers in series or parallel?

Does anyone have any experience with removing the factory cooler Tstat, and running the engine in such form?
If the amount of added oil warm up time is negligible (1 min) than it would be worth it to me to remove a possible failure point.

Thanks..

 

running two oil coolers to me is only necessary if running some serious power and not street driven, it also would take away air from radiator

 

Sounds like he does and his experience backs up my theory...

 

We run two stock coolers parallel on SCCA EProd cars. One wasn't cutting it here in Fla. Temps stay about 200F with no t-stats but we take about 10-15 minutes to warm things up before a race or session. We also cover part of the air intake for the coolers if its a little cooler than 80F. If you were moving in traffic while trying to warm up with no t-stats it would take forever, depending on ambiant temps it might never get up to the proper temp.

 

The double coolers will cause a pressure drop. You should still run a thermostat. higgi has documented this if you search under his name. To say that more coolers wont provide more cooling is correct but also bogus crap. It wont provide more cooling it will provide more cooling capacity to the system. If you are not cooling your system enough now it would help you. If you are capable of cooling your system below the thermostat temp then adding more does nothing but cool more oil down to available temps. Oil has an operating tempiture so run the thermostat. If you think about it if this was actuly a good idea don't you think mazda would of done it? Everyone is always try to out engineer mazda by removing **** :-/

 

How long does it take to bring the oil up to 150 with no T STAT?

I was considering 1 cooler with and 1 without, my factory TSTAT is stuck open (not intentional) and the oil still warms up in about 5 min.

Series or Parallel will probably come down to whats easier/cheaper..

 

A pressure drop to what, returning oil to the pan?


Yeah mazda had some excellent engineering, like the E shaft oil thermostat.

 

Throughout the whole oil circuit.

 

Amazingly, it doesn't seem to make a difference series versus parallel...or very little difference.

In series, the oil pressure doesn't seem to drop that much lower, but the oil temps are significantly lower.

hIGGI has gone this route.

We've run it both in series and parallel, and the gauges don't show that much of a difference on our 20B NA FC.


-Ted

 

Ted, Have you ever run without the cooler Tstat?

Series would just seem to be much easier/simpler, fewer connections no T fittings or distro blocks, and of course cheaper.

 

I believe hIGGI has got them bypassed.
I believe our 20B FC also has them bypassed, but the owner has an external oil thermostat on them now - I need to confirm this with him.
Simple way is just a nut and a bolt to plug the hole up.
It doesn't really increase the oil warm up time - the oil gets plenty warm in a hurry.
hIGGI does run a GReddy V-Spec FMIC kit in front of everything.
I think it was designed more for emissions purposes - Mazda tried to use all kinds of "tricks" to get the engine to come up to temp quicker (i.e. pre-cats, etc.).

Prior to running just one oil cooler, our 20B FC on the track was hitting 210F...220F+ easily.
With the dual oil coolers, it's stable at 200F now.


-Ted

 

the stock oil cooler is still badass though. it's way better than the FD setup for example. Are you sure you need to do this?

 

I don't get the pressure drop concern. The regulator is affecting the system after the oil goes through the coolers so the pressure will stay the same. If there is more resistance to flow in the system it will just cost you some HP.

As Ted shows even a 20B doesn't need two stock coolers. Its probably fine with 1 1/2 of them. Thats why it doesn't seem to matter if they are series or parallel. To get the maximum from both coolers they need to be parallel but if a 20B doesn't care a 13B won't either.

 

No the regulator is a bypass or a dump. It more then likely never even opens. The entire system is pressurized thats how the oil flows. If you cut that line oil would pore out of there.

 

You did plug the hole right?

 

If the regulator never opens then how can you bump the Oil pressure from maximum 75 to over 110 just by changing the F/R regulators.

Second the entire system is not presurised, after oil flows through the cooler it dumps back into the pan to be picked up again by the oil pickup tube.

It doesn't matter if there is lower pressure in the line after the cooler.

 

The rear regulator keeps the stock pressure around 70psi. The front regulator opens at around 150psi according to the training manual.
The oil gets picked up from the pan, through the oil pump, into the oil cooler, and out to the rear of the engine which then it flows to the oil filter and then goes through the e-shaft to all bearing surfaces and eventaully back into the pan. There is pressure through the entire system AFTER the oil pump and BEFORE the oil flows out of the bearing surfaces to the oil pan.

Yes it does. You should take a peak at how the oil system works in the training service manual.
http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/

 

Ok I admit where I was wrong, I thought the oil flowed the oppisate the direction of what is shown in the diagram, and dumped back into the pan after flowing into the front cover.

I have a 13b-re/rew hybrid, and changing from the RE oil bypass valves to rew units bumped loaded pressure from 70-115

I still think that an additional oil cooler to push through would only work the pump a little harder and not lower the pressure seen by the engine.

 

Damn your still wrong.

 

The pressure that the regulator is holding is equal thoughout the entire pressure side of the system. If you have 100 psi at the regulator, you have a 100 psi in the coolers, in the filter, at the bearings etc. I don't know if the pump is seeing 100 psi or maybe a little higher because of the twists and turns before the regulator. The difference is only going to be HP draw to create the flow at "x" pressure at the regulator. Some strange things happen in the e-shaft or any crankshaft as far as pressure is concerned but that is above this discussion.

The stock pump will build 180 psi pretty easily(probably higher but that was how high my guage went) even at around 4500rpm + -. So the regulator is working, not just along for the ride.

Oh yea, yes the bypass holes are plugged on the race cars. We just keep the rpm's low during warm up in the paddock. There is about 8.5qts of oil in the system and the water t stat is a plate with a hole in it so no t stats at all.

 

Something I didnt see noted in this thread is the fact that not only will airlfow be compromised to the second cooler, but also the first in this setup. How much is to be found out, but it will be effected. When you plumb a deflector or ducting to feed the second cooler you are going to increase the air pressure behind the first oil cooler. This will likely result in less airflow through the first cooler. In effect you will lower airflow through both.


I would try to find a way to set them up so that they are both exposed to fresh air. This will get you better cooling out of the secondary cooler without effecting the airflow through the first oil cooler.


someone correct me if I am wrong.


BC