[tetsuo111]

hassmaschine

Can you (or others) offer insight for spec'ing the optimal T-stat temp for an aux oil cooler?

I'm looking at an installation similar to Pete's and Tom D's, and many others. Basically similar to the 335i pax fender well position, withusing Setrab 619-7612 core and aftermarket T-stat. Improved Racing and Mocal have units triggered for 185 / 203 / 215 deg F.

My goals are power and enhanced longevity and reliability. I'll trade mpg efficiency for gains in the other two.

I'm doing this because I had heat issues last track day, resulting in power de-rate and transmission choke (massive latency to shift, even in manual mode). The car felt like a station wagon on a road course with sports cars. First time it happened, it was very frustrating, and I want to fix it. The sole difference from last season is replacing the OE open diff with a 80 lbs ft 4 clutch LSD. Since replacing diffs, the car has never felt the same. In a bad way...

I found this online - I know there's clues here, but must be the heat 'cause it's not helping:


Map Controlled Thermostat

The map controlled thermostat is located externally near the electric water pump. The thermostat is controlled by the ECM an operates in conjunction with the N52 Heat Management System.


Quote:
This means that four different temperature ranges can be implemented:

* 112°C ECO mode (economy)
* 105°C Normal mode
* 95°C High mode
* 80°C High + mapped thermostat mode

The coolant control sets a higher cylinder head temperature (112°C) if the engine control unit determines ECO mode based on the current operating conditions.

The engine is operated with relatively low fuel consumption in this temperature range as the internal friction is reduced.

An increase in temperature therefore favors lower fuel consumption in the low load range. In HIGH and mapped thermostat mode, the driver wishes to utilize the optimum power development of the engine. The cylinder head temperature is therefore reduced to 80° C.

This results in improved volumetric efficiency, thus increasing the engine torque. The engine control unit can therefore set a certain operating mode adapted to the respective driving situation. Consequently, it is possible to influence fuel consumption and power output by means of the cooling system.


I'm also designing aux cooling for the diff and 6AT. If you have insight to share about T-stat settings for those too, I'm all ears. Thanks

[justpete]

Originally Posted by tetsuo111

hassmaschine

Can you (or others) offer insight for spec'ing the optimal T-stat temp for an aux oil cooler?

I'm looking at an installation similar to Pete's and Tom D's, and many others. Basically similar to the 335i pax fender well position, withusing Setrab 619-7612 core and aftermarket T-stat. Improved Racing and Mocal have units triggered for 185 / 203 / 215 deg F.

My goals are power and enhanced longevity and reliability. I'll trade mpg efficiency for gains in the other two.

I'm doing this because I had heat issues last track day, resulting in power de-rate and transmission choke (massive latency to shift, even in manual mode). The car felt like a station wagon on a road course with sports cars. First time it happened, it was very frustrating, and I want to fix it. The sole difference from last season is replacing the OE open diff with a 80 lbs ft 4 clutch LSD. Since replacing diffs, the car has never felt the same. In a bad way...

I found this online - I know there's clues here, but must be the heat 'cause it's not helping:


Map Controlled Thermostat

The map controlled thermostat is located externally near the electric water pump. The thermostat is controlled by the ECM an operates in conjunction with the N52 Heat Management System.


Quote:
This means that four different temperature ranges can be implemented:

* 112°C ECO mode (economy)
* 105°C Normal mode
* 95°C High mode
* 80°C High + mapped thermostat mode

The coolant control sets a higher cylinder head temperature (112°C) if the engine control unit determines ECO mode based on the current operating conditions.

The engine is operated with relatively low fuel consumption in this temperature range as the internal friction is reduced.

An increase in temperature therefore favors lower fuel consumption in the low load range. In HIGH and mapped thermostat mode, the driver wishes to utilize the optimum power development of the engine. The cylinder head temperature is therefore reduced to 80° C.

This results in improved volumetric efficiency, thus increasing the engine torque. The engine control unit can therefore set a certain operating mode adapted to the respective driving situation. Consequently, it is possible to influence fuel consumption and power output by means of the cooling system.


I'm also designing aux cooling for the diff and 6AT. If you have insight to share about T-stat settings for those too, I'm all ears. Thanks

A trans cooler should be highest priority to offload the coolant loop.

[tetsuo111]

Originally Posted by justpete

A trans cooler should be highest priority to offload the coolant loop.

Thanks for that - is 185 deg about right for the 6AT cooler? I read that anything above 200 deg F negatively impacts trans fluid lifespan. But I read it on the Internet.... Would also need to add a lube pump as well, yes?

Do you have aux cooling for your trans?

[justpete]

Originally Posted by tetsuo111

Thanks for that - is 185 deg about right for the 6AT cooler? I read that anything above 200 deg F negatively impacts trans fluid lifespan. But I read it on the Internet.... Would also need to add a lube pump as well, yes?

Do you have aux cooling for your trans?

Not sure if there's a thermostat on the AT cooler, found this with a little googleosity -- http://www.andysautosport.com/automa...rs/bmw_x5.html

You need the 215 or higher temp thermostat on your oil cooler even though it doesn't really matter all that much.

[tetsuo111]

Found this info from a BMW document. I think this implies a 185F deg trigger for an aux setup.

Stock trigger point is 103C / 217F. The stock T-stat uses an embedded 12V heating element controlled by the ECU to have 4 operating modes (see post 1). The heating element turns on when the ECU decides the driver wants 'power mode (80 deg C High + mapped thermostat mode).

If I understand correctly, the stock T-stat opens at 103C without ECU intervention. With ECU intervention via the embedded 12V heating element, the T-stat opens at 80C.

So if I want cooler temps, the lowest the OE 'stat opens is 103C. If I want the OP down at 85C, I need a 185F t-stat.

Please enlighten me if I'm missing something significant

http://www.meeknet.co.uk/e38/E38_Map_Thermostat.pdf

[justpete]

Originally Posted by tetsuo111

Found this info from a BMW document. I think this implies a 185F deg trigger for an aux setup.

Stock trigger point is 103C / 217F. The stock T-stat uses an embedded 12V heating element controlled by the ECU to have 4 operating modes (see post 1). The heating element turns on when the ECU decides the driver wants 'power mode (80 deg C High + mapped thermostat mode).

If I understand correctly, the stock T-stat opens at 103C without ECU intervention. With ECU intervention via the embedded 12V heating element, the T-stat opens at 80C.

So if I want cooler temps, the lowest the OE 'stat opens is 103C. If I want the OP down at 85C, I need a 185F t-stat.

Please enlighten me if I'm missing something significant

What aux cooling thermostat are you talking about here?

[tetsuo111]

Specifically talking about removing the stock N52 103C T-stat, blocking the OFH, and running an aux core and external T-stat. Very similar to your setup. Just want to spec the T-stat.

[justpete]

Originally Posted by tetsuo111

Specifically talking about removing the stock N52 103C T-stat, blocking the OFH, and running an aux core and external T-stat. Very similar to your setup. Just want to spec the T-stat.

I'm lost, the only thermostat we have in N52 engines is the coolant thermostat which should be left alone. Adding an oil cooler could use the N55 thermostat on its OFH or a bypass plate and an external oil thermostat. The temp on this has to be above the boiling point of water.

[Taskmaster]

How Am I Missing These Threads?

[tetsuo111]

I'm still not following...

335i oil temperature is managed using the ECU / MAP to control an unusual T-stat. The T-stat differs from a traditional unit by having 4 operating points @ 112 / 105 / 95 / 80 deg C using both electrical and mechanical means. The higher temp OPs are emulating a Carnot cycle to maximize thermodynamic efficiency. The lower temp OPs trade operating efficiency for more power. The stock T-stat opens mechanically at 103C, and uses electrical heating inside the unit to 'trick' it into opening earlier for the cooler OPs.

If my goal is to also trade thermodynamic efficiency for more power, and I'm using an aftermarket T-stat without the electric heating element, it seems that a lower-temp mechanical trigger point is necessary to emulate the stock low-temp BMW power modes.

In this specific case an 85C / 185F mechanical aftermarket T-stat seems like the appropriate solution for the desired result of more power.

[justpete]

Originally Posted by tetsuo111

I'm still not following...

335i oil temperature is managed using the ECU / MAP to control an unusual T-stat. The T-stat differs from a traditional unit by having 4 operating points @ 112 / 105 / 95 / 80 deg C using both electrical and mechanical means. The higher temp OPs are emulating a Carnot cycle to maximize thermodynamic efficiency. The lower temp OPs trade operating efficiency for more power. The stock T-stat opens mechanically at 103C, and uses electrical heating inside the unit to 'trick' it into opening earlier for the cooler OPs.

If my goal is to also trade thermodynamic efficiency for more power, and I'm using an aftermarket T-stat without the electric heating element, it seems that a lower-temp mechanical trigger point is necessary to emulate the stock low-temp BMW power modes.

In this specific case an 85C / 185F mechanical aftermarket T-stat seems like the appropriate solution for the desired result of more power.

The electrically controlled thermostat is the coolant thermostat. I believe the oil cooler thermostat on the OFH is not electrically controlled but I'm sure someone will correct me if I'm wrong.

[rjahl]

Originally Posted by justpete

The electrically controlled thermostat is the coolant thermostat. I believe the oil cooler thermostat on the OFH is not electrically controlled but I'm sure someone will correct me if I'm wrong.

I just pulled my engine oil cooler and there is no thermostat in it.

My engine has on electronically controlled engine coolant thermostat and one bimetallic spring controlled thermostat in the radiator for the transmission fluid.

The transmission thermostat should be left stock, just ensure you coolant temperatures in the radiator stay good.

[justpete]

Originally Posted by rjahl

I just pulled my engine oil cooler and there is no thermostat in it.

My engine has on electronically controlled engine coolant thermostat and one bimetallic spring controlled thermostat in the radiator for the transmission fluid.

The transmission thermostat should be left stock, just ensure you coolant temperatures in the radiator stay good.

Would you recommend adding the X5 trans cooler somehow or another to offload the coolant loop from the added heat input?

[justpete]

Originally Posted by rjahl

I just pulled my engine oil cooler and there is no thermostat in it.

My engine has on electronically controlled engine coolant thermostat and one bimetallic spring controlled thermostat in the radiator for the transmission fluid.

The transmission thermostat should be left stock, just ensure you coolant temperatures in the radiator stay good.

Isn't the oil cooler thermostat in the plate on the side of the OFH where the lines are attached?

[rjahl]

Originally Posted by justpete

Isn't the oil cooler thermostat in the plate on the side of the OFH where the lines are attached?

Pete,

I did not see it but I could be wrong.

I thought the coolant thermostat controlled the temperature of the coolant running through the oil cooler.

[justpete]

Originally Posted by rjahl

Pete,

I did not see it but I could be wrong.

I thought the coolant thermostat controlled the temperature of the coolant running through the oil cooler.

The coolant and oil loops come together in the OFH, I think, to speed warming up the oil but I don't think it's that much of a coupling, iirc. Could be wrong about that. Regardless, the blank off plate I used to connect my oil cooler is called a thermostat delete plate so I'm guessing there's one built into the stock part.

[justpete]

Reviewing this document (again): http://lindvigs.com/obioban/spec.pdf

The oil/coolant exchange is on the 5 series, at least back then, but it's clearly not on mine or any other non-330i N52.

[rjahl]

Originally Posted by justpete

Would you recommend adding the X5 trans cooler somehow or another to offload the coolant loop from the added heat input?

I'm not sure putting an external transmission cooler drops the the heat load that much. It helps keep the gearbox cooler by putting the gear cooler in colder air but the air passing through this cooler is now heated and passes through the radiator and therefore reduces the heat rejected by the radiator.

Adding total radiator frontal area or adding air flow makes the biggest difference.

I'd log it and decide what I need.

"Years" ago I built a toy car, Pontiac Sunbird 1976 with a 350 Chevy, Phoenix AZ and could not keep the thing cool. Extra core in the radiator did not help. Only massive airflow kept the coolant temps down, big fan on the water pump and a big electric fan. The car had a very small grill area and it just took a big fan(s)to pull all of the heat away.

I was so happy that I did not install the 400 small block that I wanted to use.

[rjahl]

Originally Posted by justpete

The coolant and oil loops come together in the OFH, I think, to speed warming up the oil but I don't think it's that much of a coupling, iirc. Could be wrong about that. Regardless, the blank off plate I used to connect my oil cooler is called a thermostat delete plate so I'm guessing there's one built into the stock part.

I'm having problems with this. Do you have on oil cooler on the 328? RealOEM seams to show that you don't. I thought all of the 3.0 liter N52s had a cooler mounted against the OFT.

[justpete]

Originally Posted by rjahl

I'm having problems with this. Do you have on oil cooler on the 328? RealOEM seams to show that you don't. I thought all of the 3.0 liter N52s had a cooler mounted against the OFT.

Mine didn't.

[hassmaschine]

tetsuo111,

What you're talking about isn't going to get the results you think it will. All it will do is result in a less efficient engine. It will also make your car take longer to reach operating temperature.

The 113 degree setting is ONLY at a lightly loaded continuous cruise. For example, if you were on the freeway at a constant speed and load, it will allow the thermostat to stay closed until 113 degrees in order to reduce friction in the engine (and gain a little fuel economy).

If you are on the track, it will almost certainly be commanding the thermostat to open at 80 degrees. Further, these values can be changed if you wanted different thresholds for each level. But the stock settings are fine. You don't want your engine to run super cold (people would often have overheating BMWs, due to an old radiator, improper bleeding procedure, broken fan, or bad WP, and install a 70c thermostat under the mistaken impression it would help their problem).

Also, it doesn't directly tie into oil temps anyway. Oil temps are usually higher than coolant temps - especially when you're on a track (or just driving aggressively) and the thermostat is opening at 80c anyway.

The solution to oil temperatures is definitely an oil cooler, whether you need to modify or replace the oil cooler housing thermostat I do not know.

[E91 M Sport]

This thread has touched on just about every fluid temp except the washer fluid

To me the OP's issues is the trans going into limp mode due to excessive fluid temps. As rjahl mentioned he should log those temps and see where they go (might be scary to know!). I'd then add an external trans cooler with a thermostat controlled auxiliary fan mounted right to the cooler set to come on when you get near those temps.

Something like this. Of Course it'll take some fabrication to tie it all in neatly but that's the fun part in my opinion.