Fine control over oil cooling system

Hi! I have a stock 2018 GT86.

I am reaching oil temperature of 130°C after a few minutes of spirited driving on the street. I am not comfortable with that higher temperature (or, to be more precise, with the associated reduction in pressure) to attend a track day and spend way too much time cooling down my car on the street.

For this reason, I would like to install an oil cooler. (I am also going to install a oil pressure sensor with warnings).

I would like to say that this isn't my daily driver, it's driven just for fun. I usually do something like 10.000 km/year. I don't drive it often but, when I do, I drive for 300+ km.

That's just to give you an idea of the use of my vehicle.

I want to find a way to keep my oil temperature in the right spot, without the risk of overcooling it (it happens frequently with oil to air coolers during winter, for example).

The off-the-shelf thermostatic oil coolers are very expensive and come with their own set of disadvantages. One of them is driving with overcooled oil when not driving hard.

I have obviously thought about the Subaru oil to water exchanger but they don't seem to be good enough for track days or even very hard street driving (from the experience of a few close friends).

So I looked for a bigger oil to water exchanger and found Laminova's ones.

They give me the idea of being really bulletproof. Unfortunately, the medium size one is around 400€ (for reference, I could get a setrab 19 row oil to air cooler for about 180€) and finding enough space to mounting it isn't easy. Have you ever had experience with that kind of coolers?

If choosing the oil to air type of cooler, I want to be able to get control over my oil temperature: to do it, I have come up with 2 ideas.

They seem to be different from 99% of applications but given that my car will see highway driving, mountain spirited driving and some trackdays, some compromises have to be made.

Idea #1

• Buying a Setrab oil to air cooler (probably a 6 series - 19 rows or something like that)

• Mounting it laterally (like all the kits for forced induction vehicles)

• Installing a duct on the front of the cooler

• Use a throttle body to control the amount of airflow to the cooler (with a dedicated table inside the ECU maybe)

In this way, I could have no airflow to the cooler during start up/warming up (especially important during winter) and increase it as soon as the engine gets hotter.

Idea #2

• Buying a Setrab oil to air cooler (probably a 6 series - 19 rows or something like that)

• Mounting it laterally (like all the kits for forced induction vehicles)

• Make sure it doesn't get a lot of airflow (very probably without any cut-out holes in the bumper/tubing/ducting)

• Installing a fan-pack on the rear of the cooler

• Use fans to keep oil temperature in the right spot (with a dedicated table inside the ECU maybe)

In this way, I could keep the fan-pack switched off during start up/warming up and switch it on/increase its speed as soon as the engine gets hotter.

I tried to list a few pros/cons about this 2 setups.

Idea #1

Pros: doesn't need a constant power supply

Cons: speed dependant, doesn't work when stationary

Idea #2

Pros: not speed dependant, works when stationary

Cons: needs continuous power, even with the fan-pack switched off some air will find its way through the cooler (maybe longer warm up times?) otherwise I should find a way to cover the cooler from airflow as good as I can.

I am attaching a quick schematics (sorry for my bad drawing) about the 2 installations I thought, a picture of the Laminova oil to water exchanger fitted to a GT86 and, finally, a picture showing the type of duct I would use.

What do you think about my ideas?

I would really like to discuss them, maybe someone could be interested too!

Simpest and cheapest might be to simply plumb in an oil cooler without a thermostat, and have a blanking plate/cover you can put over it in normal/winter use, and remove when doing 'spirited' driving. It will depend on where you have it placed, though.

As Gordon said, the simplest solution here is the best. Mount the cooler with good (preferably ducted) airflow, and then make some blanking plates to handle the different weather conditions that you encounter.

From experience with running these vehicles in a Race series in Australia, where they are exposed to ambient temps between 5c and 45c it is quite easy to get the oil temps up on the engine when it is under load (even on the 5c day we had oil temp issues) and a decent sized oil cooler is a must. We also found that over about 115c oil temps using the standard weight oil, there was a loss of camshaft aim control on the Bank 2 Inlet camshaft, this is also the camshaft that has the HPFP on it, which meant that the DI fuel pressure control was erratic as well.

Thank you Gord and BlackRex for the answer!

I have obviously thought about a non-thermostatic oil cooler in conjunction with a blanking plate.

However, what I don't like about this setup is that... It's fixed.

Let me make an example: let's say I want to go out for some mountain driving (~1 hour of freeway from the city centre, where I live) and the outside temperature is 10 °C. At the beginning, I would prefer to have some blanking, otherwise my oil would struggle to heat up and maintain the correct temperature (I'm happy between 100 and 115 °C with 5W30 oil on my car).

I could use some sort of blanking for this part, than I would need to get out of the car, remove it, do the mountain driving, re-put them for the freeway part, ecc.ecc...

I would call this a static system, there is no way to have a fine control over it...

What if my oil temp is too high when the radiator is blanked and too low when exposed to airflow?

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I definitely think that your idea is good, cost effective and simple...

But, just thinking :) , wouldn't a 'dynamic' system be better? With better I mean able to adapt to different circumstances.

What I wanted to get was a oil cooling system where I could regulate the airflow through the cooler (as you said) without the need to find creative ways to attach some cardboard over the cooler or something like that.

Something where I could, for example, have a butterfly valve to control the amount of air that goes through the cooler with a 3 position switch (no airflow, 50% open, 100% open).

That's obviously just an example!

I would install the oil cooler and do some data logging, you may be surprised about how the oil heats up even under light load conditions (just the same as the coolant in the engine) and how it maintains that temperature over a wide range of conditions. Once you have a good baseline for the temperature of the oil, then you can start adding or removing airflow through the cooler to provide more cooling for the oil.

I'll definitely try to log some data!

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Speaking about the size of the cooler...

Would you go with a smaller 13 rows or a bigger 19 rows?

I would go for the one that fits the best. You may find that the 19 row has too much cooling capacity as well. I have a fully ducted 13 row setrab oil cooler on my racecar (Subaru EJ207) and I do not have oil temperature issues even during a 50km race on a 35+degree day, the driver on the other hand does.

If you can only afford to buy and fit one, then I would suggest you go with the larger one. It's cheap and easy to make it cool less, but you would have to replace the entire cooler to make it cool more if you have one too small.

That said, using the experience of someone like Stephen to get the correct size is good way to get it right the first time.

Regarding the oil cooler dimensions, don't forget most are available in two widths - it may help placing it.