Imagine if our N54 cars had a coolant temp gauge instead of an oil temp gauge...
I suspect the N54 community originally got all bent out of shape over oil temps because we were given an oil temp gauge instead of a coolant gauge. And with stock oil temp being set to the "astonishingly high" 240F what else were we to do but cry "That's crazy stupid high oil temp, WTF BMW?!?", leading BMS et al. to create inexpensive ways to keep oil temps lower like BMS' relatively simple oil diverter valve as well as ER's popular and more complicated oil cooling solutions like its single "Sport" auxiliary oil radiator and dual "race" oil radiator kits. These all seem to work fine for what they are designed to do, but others on this forum have noted that 240F oil temps are desirable for daily driving, emissions and fuel economy. But the situation is quite different for autocross and HPDE type track events during which our beloved N54s are pushed hard constantly for 20-30 minutes and limp mode inevitably ensues. Psychologically I think we all believe limp mode is triggered by high oil temps simply because that's the guage we stare at in the dash. I suspect if we were given a coolant temperature gauge instead then seeing coolant temps climbing greater than 300F would instead have hightened our awareness much earlier towards creating better coolant cooling solutions. We now know that both high oil temps (>300F) and high coolant temps (>250F) will cause limp mode. Indeed, the BMW engineers realized the coolant cooling deficiency in the N54 and subsequently designed the PPK system (larger fan and auxiliary coolant radiator) for reducing coolant temps, much like the way they added the oil cooler in 2007 having seen the deficiencies of the first N54-powered 335i cars produced in 2006. While many on this forum would probably argue that the PPK system is under-designed for real track work, I find it interesting that the BMW engineers didn't also include an upgraded oil cooler with the PPK system.
I think we should pay more attention to mods for lowering coolant temps. We now know that coolant temps above 250F are a major trigger for the DME to pull power and limp mode. And excessive coolant temps are especially a concern for AT cars like mine in which the engine coolant system is integrated with the ATF coolant system such that ATF temps tend to equilibrate with coolant temps after about 25 minutes or so daily driving. Indeed, just 10 minutes of spirited driving after warm-up caused both my ATF and coolant temps to quickly reach 220F last weekend (85F ambient). While my BMS oil diverter valve helped to keep oil temps under 245F during this 10 minute sprint, I'm sure the oil temps would have quickly exceeded 250F in this short time without it. A 10-minute cool-down period driving under low load quickly brought down oil, coolant and ATF temps, to 230F, 200F, 195F, respectively.
So I'm now wondering: Does there exist a quality-kit for auxiliary ATF cooling in the driver-side front bumper, much like the ER Sport Oil Cooler in the passenger-side wheel well? Ideally the auxiliary ATF cooler would work in parallel with the current ATF/ coolant radiator heat transfer system in place. I would then be staring a lot more at my coolant temp and ATF temp gauges (thanks to MHD).
[EDIT: Justin pointed out the correct "red zones" for oil temp and coolant temps. I adjusted the above text, accordingly. Thank you, Justin. I don't think it affects my conclusion that auxiliary coolant/ATF cooling is probably equally important as auxiliary oil cooling.]
I suspect the N54 community originally got all bent out of shape over oil temps because we were given an oil temp gauge instead of a coolant gauge. And with stock oil temp being set to the "astonishingly high" 240F what else were we to do but cry "That's crazy stupid high oil temp, WTF BMW?!?", leading BMS et al. to create inexpensive ways to keep oil temps lower like BMS' relatively simple oil diverter valve as well as ER's popular and more complicated oil cooling solutions like its single "Sport" auxiliary oil radiator and dual "race" oil radiator kits. These all seem to work fine for what they are designed to do, but others on this forum have noted that 240F oil temps are desirable for daily driving, emissions and fuel economy. But the situation is quite different for autocross and HPDE type track events during which our beloved N54s are pushed hard constantly for 20-30 minutes and limp mode inevitably ensues. Psychologically I think we all believe limp mode is triggered by high oil temps simply because that's the guage we stare at in the dash. I suspect if we were given a coolant temperature gauge instead then seeing coolant temps climbing greater than 300F would instead have hightened our awareness much earlier towards creating better coolant cooling solutions. We now know that both high oil temps (>300F) and high coolant temps (>250F) will cause limp mode. Indeed, the BMW engineers realized the coolant cooling deficiency in the N54 and subsequently designed the PPK system (larger fan and auxiliary coolant radiator) for reducing coolant temps, much like the way they added the oil cooler in 2007 having seen the deficiencies of the first N54-powered 335i cars produced in 2006. While many on this forum would probably argue that the PPK system is under-designed for real track work, I find it interesting that the BMW engineers didn't also include an upgraded oil cooler with the PPK system.
I think we should pay more attention to mods for lowering coolant temps. We now know that coolant temps above 250F are a major trigger for the DME to pull power and limp mode. And excessive coolant temps are especially a concern for AT cars like mine in which the engine coolant system is integrated with the ATF coolant system such that ATF temps tend to equilibrate with coolant temps after about 25 minutes or so daily driving. Indeed, just 10 minutes of spirited driving after warm-up caused both my ATF and coolant temps to quickly reach 220F last weekend (85F ambient). While my BMS oil diverter valve helped to keep oil temps under 245F during this 10 minute sprint, I'm sure the oil temps would have quickly exceeded 250F in this short time without it. A 10-minute cool-down period driving under low load quickly brought down oil, coolant and ATF temps, to 230F, 200F, 195F, respectively.
So I'm now wondering: Does there exist a quality-kit for auxiliary ATF cooling in the driver-side front bumper, much like the ER Sport Oil Cooler in the passenger-side wheel well? Ideally the auxiliary ATF cooler would work in parallel with the current ATF/ coolant radiator heat transfer system in place. I would then be staring a lot more at my coolant temp and ATF temp gauges (thanks to MHD).
[EDIT: Justin pointed out the correct "red zones" for oil temp and coolant temps. I adjusted the above text, accordingly. Thank you, Justin. I don't think it affects my conclusion that auxiliary coolant/ATF cooling is probably equally important as auxiliary oil cooling.]
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