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      07-16-2013, 12:53 AM   #953
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Drives: E90 335i, E84 X1
Join Date: Feb 2012
Location: San Francisco

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Coolant temps at Thunderhill

I forgot, one other interesting data point: on the freeway drive to the track during the previous evening I monitored my coolant temp. It reached 105C in 95F weather and noticeable humidity (Central California humidity is bad, but not East Coast bad).

During the actual track day in 104F weather, my coolant temp never got over 98C. It seems that humidity had a large impact on coolant temperature.

Originally Posted by macmacaman View Post
I updated the spreadsheet with some results from running with NCRC at Thunderhill on June 30th. We had 5 run sessions of 20 minutes long. By 11am it was in the high 90's, and peaked out at 104F early afternoon. My fastest lap was 2:22, and by the last two run sessions was consistently running 2:24 to 2:26. As I was in the novice group (1 to 7 track days), I ran into a lot of traffic, so there would be the occasional slower lap.

I have the BMW performance aero kit installed, which has specific vents for the brakes, and the some larger venting, ostensibly for the oil cooler and radiator. When I saw the oil temp climbing up to 280F - 290F, I started shifting into 4th early. I never went into limp modes. I am not sure if I had some power reduction.

A friend of mine also with an E90, sport package, completely stock, went into limp mode once and threw a VANOS code in his fourth session, but cleared it and continued. No times for him, but he was running slower than me.

Some other interesting thermal data: with a thermal imaging camera we measured my tire temps to be 240F, equally distributed across the tire tread, and brake pad temperatures of 518F (max temp measurable by the camera) for the entire pad.