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      06-14-2011, 01:25 PM   #401
mid-corner fun
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Drives: F80 M3, '22 X3MC
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Quote:
Originally Posted by Orb View Post
I went through the issue in this thread a few years ago...

Logging the coolant temperature is great but it needs to be in format with other parameters over time so we have idea what truly is happening. Do not rely on the temperature gauge as the absolute temperature of the system because it is only reading at one specific location and there will be local boiling in other locations.

If chose to run 100% distilled water then you will reduce the boiling point by 7-8 degrees over 50/50 solution and not advisable without a wetting additive. The best comprise is running a solution mix 70/30 with a wetting additive. With this you get addition 6-15 C reduction (feedback from other a few years ago) in coolant temperature and possible more since the wetting agent is effective at reducing localized boiling areas which is a known problem in this engine. The flow rate of the coolant will increase due the decreased viscosity of the coolant as well. The wetting agent is effective with 30/70 but half of what you would see with 100 distilled water.

If you have tune (14-15 PSI max) then you need an upgraded IC and should consider oil cooler as well. Due to the massive increase in temperature pressure drop of the IC you are going to see power reduction before you hit any cooling threshold.

If you have auto transmission there are few tips you should consider. Run the transmission in manual mode. Turn traction control completely off. This is big issue with this transmission as intervention of the traction control system adds massive amount heat back into the transmission via clutch slippage which ends up back into the coolant system.

I stopped having any coolant issues (limp mode) once I turned off traction control. Changing the coolant to 30/70 mixture with a wetting additive goes a long way at reducing limp mode but it not enough if you are running with traction control on!
100% distilled water with Mocool: Check
FMIC: Check
Oil Cooler: Check
Auto transmission in manual mode: Check (Would be crazy to attempt otherwise on the track)
traction control completely off: Check

All good points, at least in my case I'm already doing all of these.


Interesting comment about eliminating limp modes by turning off traction control, I didn't realize the effect on the transmission, I was under the impression that it kills rear pads only. Good info, thanks.
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