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      11-15-2012, 06:53 PM   #24

Drives: BMW
Join Date: May 2008
Location: Parts unknown

iTrader: (0)

Originally Posted by ajm8127 View Post
Your estimations for the ATF temp exiting the stock cooler make sense when you consider they correspond with the 108C and 95C temps of two of the operating modes for the cooling system. I have noticed 108C temps in stop and go driving, and around 95C temps in normal driving with my driving style, which is on the slightly more aggressive side. This is the temperature of the water exiting the head. Of course the temp of the water entering the water to oil heat exchanger will be lower because it has just passed through the radiator, but you can't expect the heat exchanger to bring the ATF temp all the way down to match in inlet temp of the water. That is unreasonable.

I also would not expect your oil or water temps to change with your setup because you are cooling the ATF after the stock heat exchanger, so the same amount of heat is being transferred to the water as before. The only difference is the AFT returning to the transmission is now cooler. However, if you are putting cooler fluid into the transmission, the fluid coming out should be a little cooler as well, which may translate into slightly cooler water temps. Time will tell.

I am curious to see what happens at the track with your setup. Obviously your ATF temps will be lower. You said in the other thread that you've never had a problem with limp mode, and I wouldn't expect you to this time especially considering it is November, and ambient temps, and more importantly, track temps, will be lower than in July during a sunny day.

Component protection starts at 117C (234F) so as long as your water temp at the heat outlet is below that, you should be fine. After this the engine output is reduced, which is not what you want at the track.

Regardless, have fun.
Yes I agree with much of what you said. I think this will help at the track to keep having smooth transmission changes and really is more of a reliability mod than anything else. It will likely do little to none in the way of perfromance. The one thing I want to point out is that 117C is 242 F, not 234F. The highest water temp I have seen is 231F at the track. I did notice that it spiked from 217-231 in a matter of seconds so I did back off a bit when I saw that occur even though I had another 8 F to go before limp mode. I have seen limp mode at the track but never related to water or oil temps. I did one time have a limp mode I think related to traction control but I did not have access to a code reader so not certain.