In my experience my 2008 135i with a mild tune encounters power reductions due to overheating coolant during extended track sessions.
Our ECU begins to progressively reduce power once coolant reaches 117°C (243°F), and the effect is immediately apparent when driving on the track. A similar effect occurs once the oil reaches 151°C (304°F), however, my coolant reaches the limit before the oil does.
My experience is not different from others. I thank
xBlueStreakx for steering me towards the CSF radiator:
http://www.1addicts.com/forums/showp...56&postcount=1
He also pointed out this article:
http://oppositelock.kinja.com/my-tho...ato-1745809742
Which leads to this this thread on E90POST which deals with the problem exhaustively:
http://www.e90post.com/forums/showthread.php?t=412156
So, I have purchased and installed a CSF p/n 7045 radiator. Removing and installing the radiator is somewhat difficult due to the very limited space up front. I found disconnecting the oil cooler lines to greatly help the installation. I ended up replacing the cooling fan shroud as well as mine had cracked at some point.
The cooling fan shroud connects to the original radiator at three points: one bolted connection at the upper RH corner, and one plastic clip on each side at mid height. The CSF radiator uses mid-height brackets that do not correctly mate up with the plastic clips. I designed a simple delrin block that provided effective clamping, while ensuring that the shroud remains properly centered on the radiator. I offer the idea up for anyone planning on installing this radiator.
The LH plastic clip on the radiator shroud needs a bit of grinding to work with my clamping block. Before:
and after:
The radiator provisions are simple brackets with clamping screws. LH Bracket:
RH Bracket:
The shroud clips only half hang on these brackets so the clamping screw does not fully engage and a slight lateral shift will allow the clip to fall off the bracket.
My delrin clamping block provides features to ensure the shroud remains centered, and it provides a good surface for the clamping screw to engage. These screws have captive washers which provide no function in this installation. I installed them with Loctite to ensure they wouldn’t back themselves out over time.
LH side with Clamping Block:
RH side with Clamping Block:
