Quote:
Originally Posted by FastDriver
25 is pretty rough. Never had to go that low. Haven't had a hill or mountain where it couldn't maintain max engine speed in 3rd gear, which works out to about 60. I'd be worried about the cooling capacity of the heat exchangers below 40mph. Then, I'd be watching engine & trans temps as best I could.
Sounds like you have a lot of truck to haul with your 450. The most I've ever had was still just under the GCWR at around 19,700 lbs including the truck & trailer.
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Yeah, it was damn slow, going up the Raton pass. It was running in reduced power mode and not making any boost I suspect. Interestingly enough, the oil temp never moved when making the hill climb, even with its slow speeds. We did turn of the a/c for that last little bit of power...
Did the same drive in 2015 in my 335D, which had no issues going up raton with the cruse set to 80mph. The M wouldn't either if it wasn't in limp mode, it was a bad MAP sensor that caused the whole problem $350 under warranty.
I have noticed that my 550i, the oil temps will rise steadily when slow going on a steep grade. I drove quite a few times last summer on the going to the sun road in Glacier, and when I'd encounter traffic my oil temps would cruise up into the 270F range. The X5M does the same thing when not in limp mode in colorado, long uphill grades at say 65, the oil temp rises a lot. But I'd figure the M would do better then the 550i in general as it has substantially more cooling than a regular BMW for track purposes.