,

Let’s look at the scenario of the oil cooler in front.  I recorded oil temperatures of over 130C at the track.  Air flows through the oil cooler getting heated up and now flows through the A/C condenser.  On the street, this reduces the performance of the A/C system as we now have warmed up air hitting the condenser. On the track, the A/C is off, so we can ignore the condenser, but now we have hot air hitting the radiator.  Let’s pretend the air coming off the oil cooler is 100C.  100C air hitting the radiator does absolutely nothing to reduce the temperature of the coolant if the coolant is also at 100C.  If the coolant is at 90C, then the air coming of the oil cooler would actually heat up the coolant!  I actually have no clue what the air temp coming off the oil cooler would be (depends on ambient air temp, oil temp, oil cooler effectiveness, air flow rate through the cooler, oil flow rate), but I made up that number to illustrate the concept.

Okay okay…. I’ll guesstimate the numbers a little more closely.  If the oil going into the cooler is 130C and the air temp is 30C, then the air coming off the oil cooler has to be somewhere in the middle.  I could calculate it based on a guess for oil flow rate, knowing the specific heat capacity of oil, knowing the size of the cooler, guessing an effectiveness of the oil cooler, and flow rate/speed of the air (and specific heat capacity of air) going through the cooler.  The faster/more volume of air going through the oil cooler, the cooler the air will be coming off of it.  Without making any real calculations, a slightly more accurate guess would be the oil temp dropping from 130C to 100C and the air temp rising from 30C to 50C (which is highly dependent on airflow rate).

 The front end of the car.  I’m saving the blocked off openings for possible future use.

 In the middle of the main opening is the horn and the A/C dryer (at least I think it’s the dryer).  As they are right smack in the middle, they prevent putting a big oil cooler there.
 The future home of the oil cooler behind the radiator.

So, I opted to put the oil cooler behind the radiator.  Using some make pretend numbers again, let’s say the air coming off the radiator is 50C.  If the oil is at 130C, then the oil will still be cooled by the 50C air.  Not as good as fresh air at 30C, but still a big temperature difference of 80C.  This is a preferable situation compared to having the oil cooler in front where the temperature difference between the air coming off the oil cooler is 50C and the coolant around 100C.  That’s only a 50C temperature difference.  Heat transfer is all about temperature difference; the larger the difference, the greater the heat transfer.

 To enable the oil cooler to fit, I had to get a SPAL 11″ slim fan to replace the stock one.  I cut off the stock connecter from the stock fan and wired it up on the SPAL.

1. waldo mejia says:

Why did you choose such a big oil cooler? the aftermarket does not offer such large applications.

Does it have to do with the flow rate of the s2000’s oil pump at high rpm?

I have oil cooler setrab of 18 lines and I see that after 5 minutes on the track the pressure drops to 64psi in vtect and the temperature to 233f

my car is supercharger kraftwerks and the oil cooler is located behind the supercharger intercooler

thanks

1. Khiem Dinh says:

Part of the reason was because I put the oil cooler behind all the other heat exchangers, so it was getting the hottest air. Check out the article that is Part 23: Testing air temps through coolers and vents. I also only had one chance to do this setup without testing various combinations, so I went large to be safe. The benefits being more cooling, greater oil capacity, and less pressure drop. I don’t think I’ve ever seen below 75-80psi in the VTEC transition with oil temps at 240F.

2. waldo says:

my car have kraftwerks kit, please recommend configuration for oil cooler

1. Khiem Dinh says:

Use an oil cooler with more rows. The greater number of rows, the lower the pressure drop and the more cooling. Also, what size lines are you using? I’m using -12. Lots of kits use -8 which is too small in my opinion. I would say at least -10.

1. Ed says:

Why does a greater number of rows equate to a lower drop in oil pressure? Is it because the greater number of rows allows for more paths for the oil to flow and thus less restriction to flow? Also, If I were to take a 30 row oil cooler core and make it into a triple pass where each pass has 10 rows, would that create a pressure drop equivalent to using a 10 row single pass cooler?

1. Khiem Dinh says:

Pressure drop is a function of velocity and distance. Pressure drop increases to the square of velocity. And the longer the distance, the greater the pressure drop. So with more rows, you have more flow area, which reduces the velocity for the same mass flow rate.

A 10-row single pass would have less pressure drop than a 30-row triple pass, assuming the cores are the same width. This is because in the 30-row triple pass, the flow distance is triple the 10-row assuming the cores are the same width. And there’s going to be additional pressure drop each time the oil has to make a turn in the triple pass.

1. Ed says:

Ok that makes sense. Thank you!

3. waldo says:

what oil use in your car?

1. Khiem Dinh says:

Motul 300V 5w-30

4. waldo says:

I use a line of 16 lines behind the intercooler of my kraftwerks kit and the car easily goes up to 240f.

ask, if I add one of 42 lines behind the radiator with a fan, the temperature will I be able to control it better? What do you recommend doing to keep control of the oil temperature of my car?

The water temperature is stable at 220f

1. Khiem Dinh says:

Bigger oil cooler will certainly help. But you also need to address your coolant temps which are too high. Consider that that fans turn on at 212F. Sure, you CAN run at 220F, but it reduces the reliability of your engine and hurts power. My car is naturally aspirated, but coolant never goes over 190F even when I did track days in 103F temps. Make sure you have your heat exchangers well sealed (I used foam stuffed around them) and you certainly need a vented hood if you don’t have one already.

1. Waldo Mejia says:

hello I have a question I am using the original car water radiator thermostat, would you recommend changing the sensor to a mishimoto of less temperature? I use the street car too

1. Khiem Dinh says:

No, changing to a lower temp thermostat does nothing for reducing temps at steady state conditions. It just delays how quickly the temp will max out.

5. Karim TEGGAR says:

A friend suggested to me a rather convelling idea about oil cooling: If for example we keep the original donut (oil cooler) to circulate water (circuit with a radiator on the bumper, and an electric pump that activates with a mano connected to the oil temperature) .. What do you think?

1. Khiem Dinh says:

Yup, should work just fine. Keep in mind the OEM setup is circulating 190degF coolant. If you have a separate circuit with front mounted radiator, it should cool the coolant down close to ambient. So figure it’ll be at least 80degF cooler coolant compared to the OEM setup. You might need a variable speed pump to regulate the oil temp and not cool it too much under everyday driving conditions.

6. Paul says:

Any updates on how this is performing at the track? How is the oil temperature holding up?