N54 Cooling - Temp Control Logic and what are your temps during extended track use?

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Specialist
Platinum Vendor
Jun 4, 2018
75
#21
I'm coming at all of this from a pure track mindset, toss in a little "old school" mindset as well as @fmorelli might say.

The whole reason map controlled thermostats were developed was for emissions and efficiency. The map thermostat allows the engine to run hotter for a more thorough combustion for emissions purposes, a hotter engine heats up the oil more and thus creates less friction leading to better fuel economy, etc. But here is the cool part, (pun intended) it then can be controlled to run the engine cooler where the engine can then make more power. Again, BMW states the best volumetric efficiency is 194F coolant temp for the N54.

The electric water pump was used because you could use it to heat the car up quicker when cold by reducing flow. It can also be used to reduce flow when warm to heat the motor up even more for better emissions, and finally it can be run after the car is shut off to keep coolant running through the turbos.

I say all this because this car is meant to be a fun street car, project car, track car, etc. Emissions and fuel economy aren't my concern. I'd venture to say that most people modifying N54 motors to get 100 to 500 more WHP aren't concerned either but that of course is an assumption.

This is where I go back to road racing and the old school approach: I want power and more importantly... longevity. Running a motor at sub 200F all the time is going to make every other component last longer. Don't we all want this?

@RSL you make a fantastic point! Running the thermostat in MAP mode all the time can wear out the heating element. I found this and think an approach like this could solve that problem: https://www.mishimoto.com/bmw-n52-n54-n55-racing-thermostat.html Not saying that is the answer, maybe it is, but the concept would basically allow the thermostat to never have to use MAP mode. The pump would then have to run slower (added longevity) when the motor needs to heat up. Win win.

Thanks for the data point on the water pump being run in KFT mode for so long. Sounds like they are pretty robust. I ran an n52 based 328 in Grand Am which has an elecric water pump as well. We pounded that thing to death at full power (BOSCH Motorsport ECU) and never had a problem. Honestly, with FCP Euro's lifetime replacement, buy one from them for $350 and who cares if it fails prematurely. Unless of course its every 5k miles which then becomes a labor hassle.
 
Last edited:

RSL

Sergeant
Aug 11, 2017
275
#23
I'm coming at all of this from a pure track mindset, toss in a little "old school" mindset as well as @fmorelli might say.

The whole reason map controlled thermostats were developed was for emissions and efficiency. The map thermostat allows the engine to run hotter for a more thorough combustion for emissions purposes, a hotter engine heats up the oil more and thus creates less friction leading to better fuel economy, etc. But here is the cool part, (pun intended) it then can be controlled to run the engine cooler where the engine can then make more power. Again, BMW states the best volumetric efficiency is 194F coolant temp for the N54.

The electric water pump was used because you could use it to heat the car up quicker when cold by reducing flow. It can also be used to reduce flow when warm to heat the motor up even more for better emissions, and finally it can be run after the car is shut off to keep coolant running through the turbos.

I say all this because this car is meant to be a fun street car, project car, track car, etc. Emissions and fuel economy aren't my concern. I'd venture to say that most people modifying N54 motors to get 100 to 500 more WHP aren't concerned either but that of course is an assumption.

This is where I go back to road racing and the old school approach: I want power and more importantly... longevity. Running a motor at sub 200F all the time is going to make every other component last longer. Don't we all want this?

@RSL you make a fantastic point! Running the thermostat in MAP mode all the time can wear out the heating element. I found this and think an approach like this could solve that problem: https://www.mishimoto.com/bmw-n52-n54-n55-racing-thermostat.html Not saying that is the answer, maybe it is, but the concept would basically allow the thermostat to never have to use MAP mode. The pump would then have to run slower (added longevity) when the motor needs to heat up. Win win.

Thanks for the data point on the water pump being run in KFT mode for so long. Sounds like they are pretty robust. I ran an n52 based 328 in Grand Am which has an elecric water pump as well. We pounded that thing to death at full power (BOSCH Motorsport ECU) and never had a problem. Honestly, with FCP Euro's lifetime replacement, buy one from them for $350 and who cares if it fails prematurely. Unless of course its every 5k miles which then becomes a labor hassle.
I'm all for old school and KISS. If it works and is reliable, don't need extra complexity or added avenues for failures. I'm pretty sure those Mishimoto stats have or had fitment issues though. They either didn't actually fit N54s or only fit certain P/N housings. I don't quite remember, but if it did fit/work, easy enough.

If there were no easy aftermarket solution, probably left with running KFT or taking the thermostat apart and seeing if anything can be done to increase flow without the heating element on. I'm really not sure there is or someone would have by now. I've seen people (other cars) go so far as to buy different stats and swap the plug from that into the stat shell that came out of their car to change temps when no others were available. Not sure how feasible that would be on N54, but for all that effort, I'd just as soon run KFT mode 24/7 and potentially have to replace with an OEM every couple of years or as needed. Like you said, with a lifetime replacement, it's more labor than cost.

Sport hits KFT mode at ~90F ambient (and runs more reasonable ECTs, like 195-200F IIRC), so I'm sure there must be plenty running KFT mode for extended periods by now, whether they even know it or not. If it were a huge problem, I'd expect there would be clusters of cooling mode flashers reporting failed pumps or stats. It's been around in MHD for 1.5 years now, so I don't think KFT has a very negative impact on lifespan, especially when running lighter demands in it. As for the heating elements, they're probably not normally used at all by most of these on the road, so elements might have 0-few hours on them when starting to use it regardless of age lol

One thing I hadn't really thought about before is the where the ECT is read in the loop. If it's on the return side (and I think it is??), it would be obviously warmer than stat temp and need to take that into account. 210F minimum out may be what 195F in looks like. There are diminishing returns on ECT to other temps though, so if OCT or tranny temps are what's actually causing limps, may just need to run ECT full blast for track no matter what to keep those as cool as possible. As you can see in the screens above, 30-40F drop in ECT was maybe a 20F drop in OCT, and that wasn't racing.
 
Mar 10, 2018
122
#24
Hi there, I track my 1M. I haven’t done anything to my cooling system yet and I’m also very concerned and let down by the oil temp. My car is stock turbo with JB4 running ~17psi peak, WT EVO III large inter-cooler, stock cooling system and cowl piece removed for theoretically better air flow out of the engine bay. Here in Guangdong, I have done ZIC and GIC in 80F+ days. For my last track day at GIC on 11.10, the ambient temp was ~80F. I was testing other things so I data-logged my pulls down the front and/or back straights. Here is the data for temps at the end of the straights:

Lap # - Oil Temp - Water Temp
==== 1 warm-up lap ====
Lap 1 - 219F - 196F
Lap 2 - 249F - 214F
Lap 3 - 258F - 214F
Lap 4 - 262F - 218F
==== 1 cool-down lap and ~3 mins in the pit with fan on 100% ====
Lap 5 - 233F - 199F
Lap 6 - 260F - 220F
Lap 7 - 271F - 221F
Lap 8 - 282F - 225F

It appears that if the oil temp can be kept below 260F, water temp should be under 220F.

As a protection, JB4 goes into safe mode when oil temp goes above ~285F. Therefore, I never reached 230F water temp since oil temp goes above 280F long before that. Ideally, I would love to keep my oil temps much lower, say ~240F.

I am now tempted to put in place a second oil cooler. However, I haven't decided where I want to place it. Currently, there are two possible locations:
  1. Remove the stock aux radiator on the driver side and replace with an oil cooler.
    • Pros:
      • easy fitment, easy bracket, no cutting, not interfering with anything else
      • able to vent hot air after cooler away from the engine bay and into wheel well
    • Cons:
      • space is limited so the size of the cooler cannot be too large
      • aux radiator deleted
  2. Behind front grille, in front of the radiator and above the intercooler.
    • Pros:
      • able to fit a large cooler
      • likely more air flow than the other location
    • Cons:
      • main radiator is blocked
      • hot air vented into engine bay
What do you guys think? Which is the better location for a second oil cooler? Also, given a second oil cooler, is upgrading the one in stock location still necessary?



Lap 1
View attachment 18172
Lap 2
View attachment 18173
Lap 3
View attachment 18174
Lap 4
View attachment 18175
Lap 5
View attachment 18176
Lap 6
View attachment 18177
Lap 7
View attachment 18178
Lap 8
View attachment 18179
Awesome to see another N54 being tracked in China. I used to go to GIC all the time. Now I moved away so usually go to Ningbo instead.

I would definitely not remove the AUX water radiator on your car. I have an extra oil cooler where your aux water radiator is, and I hit power reduction due to coolant temps way before I hit oil temps that are too high. Instead you could consider upgrading your existing oil cooler to a bigger race spec one.

The only reason I still run an additional oil cooler is because I have a semi-dry oil sump system. I am sure, after you upgrade your oil cooler, you will be in the same boat as Barry and me - ie trying to figure out how to upgrade coolant cooling.
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#26
If there were no easy aftermarket solution, probably left with running KFT or taking the thermostat apart and seeing if anything can be done to increase flow without the heating element on. I'm really not sure there is or someone would have by now. I've seen people (other cars) go so far as to buy different stats and swap the plug from that into the stat shell that came out of their car to change temps when no others were available. Not sure how feasible that would be on N54, but for all that effort, I'd just as soon run KFT mode 24/7 and potentially have to replace with an OEM every couple of years or as needed. Like you said, with a lifetime replacement, it's more labor than cost.

Sport hits KFT mode at ~90F ambient (and runs more reasonable ECTs, like 195-200F IIRC), so I'm sure there must be plenty running KFT mode for extended periods by now, whether they even know it or not. If it were a huge problem, I'd expect there would be clusters of cooling mode flashers reporting failed pumps or stats. It's been around in MHD for 1.5 years now, so I don't think KFT has a very negative impact on lifespan, especially when running lighter demands in it. As for the heating elements, they're probably not normally used at all by most of these on the road, so elements might have 0-few hours on them when starting to use it regardless of age lol

One thing I hadn't really thought about before is the where the ECT is read in the loop. If it's on the return side (and I think it is??), it would be obviously warmer than stat temp and need to take that into account. 210F minimum out may be what 195F in looks like. There are diminishing returns on ECT to other temps though, so if OCT or tranny temps are what's actually causing limps, may just need to run ECT full blast for track no matter what to keep those as cool as possible. As you can see in the screens above, 30-40F drop in ECT was maybe a 20F drop in OCT, and that wasn't racing.
As for, "if someone would by now"... The e36 and e46 M3 are 23 and 17 years old respectively and there are still products being developed for those, albeit slower these days of course. The N54 is only 11 years old, young in the world of aftermarket development and an infant in the track world. Go to a NASA, BMWCCA, Jeffapalooza, Chin, etc event and you will be hard pressed to find a an N54 based car, they are dominated by e30s, e36s and e46s. The track world is a HUGE untapped market for N54 evolution. What I mean by all this is that the cooling system of the N54 needs work for track guys, current solutions just don't cut it and there is much room for improvement in my opinion.

There should be a setting in MHD called "Track Mode". Basically run the water pump full speed at all times and run MAP thermostat open fully at all times. Before you load your car on the trailer, or when you get to the track if you drive there, load MHD "Track Mode" then when done with the weekend load street mode back and carry on.

The current MHD setting for "Race Mode" states: Coolant high + kft 80c(85c / 80c Stock) (This mode is activated at full throttle) Amb threshold for high + kft 27c (37c Stock)

Look at the histogram below from a lap on a track. You are at less than half throttle 38% of the time (braking zones and throttle modulation coming out of the turn). And there are plenty of track events through the season where there are sessions below 27c ambient temp. So based on this, when in "Race Mode" you are not targeting KFT at all times. Obviously Race Modes of normal and high try to target 85c as well which is great. But what is the DME doing when it switches between modes? Does it momentarily slow the pump down? I don't know. This is why I tagged @jyamona to see if he could enlighten me/us on the details of the logic as maybe i'm miss understanding it. This takes me back to the KISS. Remove without a doubt, the waterpump or thermostat fluctuating and just run them full speed and full open respectively.

Clearly a "Track Mode" can be accomplished with the XDF approach so maybe its a moot point, but it sure would be nice to have it as a setting in MHD!



throttle.JPG
 
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[email protected]

Specialist
Platinum Vendor
Jun 4, 2018
75
#27
One thing I hadn't really thought about before is the where the ECT is read in the loop. If it's on the return side (and I think it is??), it would be obviously warmer than stat temp and need to take that into account. 210F minimum out may be what 195F in looks like. There are diminishing returns on ECT to other temps though, so if OCT or tranny temps are what's actually causing limps, may just need to run ECT full blast for track no matter what to keep those as cool as possible. As you can see in the screens above, 30-40F drop in ECT was maybe a 20F drop in OCT, and that wasn't racing.
It is measured as the coolant comes out of the head at its hottest point. The N54 has two hot coolant outlets, one goes to the radiator (radiator hose) and the other (thermostat hose) straight to the thermostat. The hot coolant in the thermostat hose triggers the thermostat to open which then allows coolant to flow through the radiator, IE through the radiator hoses.
 
Aug 11, 2017
1,614
Virginia
#28
I just would like to add another point, which actually stemmed from @[email protected] in a conversation on the phone yesterday.

BMW designs are significantly compromised by constraints, namely emissions. Look at the PCV system - hardly performance oriented. The headaches in the cooling system come from emissions; otherwise the motor might always be kept at VE. Instead it is often targeted to run higher ... why ... emissions. So for target street use, that is up to around ~230°F, which in practice would be stoplights, et cetera. The closed loop control system - variable tstat, water pump, and radiator fan, with corresponding sensors and likely feedback from usage (TPS, load, ...) and while navel gazing, likely predictive targets for desired emissions profiles (and performance VE profiles we assumed) - well this ain't the old school two-stage radiator fan switch, a churning mechanical water pump, and a temperature sensitive tstat spring assembly. I probably have some of the details wrong, but I believe the gist is directionally correct (and feel free to say otherwise!)

I think it is a mistake for track guys to conclude their car is fine if they can throw parts at it and keep it from entering limp mode. The car is not a VE, nor was it designed to run full tilt for 30+ minutes at a time at sub-limp mode temperatures.

I agree with @[email protected]'s perspective - the N54 is 11 years young, at least from the lens of traditional BMW model development in the aftermarket. I'm enjoying reading everyone's input on this thread!

Filippo
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#29
I think it is a mistake for track guys to conclude their car is fine if they can throw parts at it and keep it from entering limp mode. The car is not a VE, nor was it designed to run full tilt for 30+ minutes at a time at sub-limp mode temperatures.
Filippo
You know, as I think through this more, I think its a mistake for a street hot rod, drag racer, or track guy to run any more than 194F at any time. Running anything above 194F is pointless for these types of cars. We all know heat kills motors and it's components, not just IAT heat, overall engine heat, too. Head gaskets, valve cover gaskets, any other seals and o-rings will last much longer if the overall engine is kept cooler.

Imagine your are cruising along on the street, or lined up for a drag race at idle. The DME is in ECO mode and running the temp high, 210F or maybe even 220F+ and you all of a sudden get on it. Now you just spiked even more heat into the motor. You want the motor to be running cool BEFORE you get on it.

This reminds me of the old days racing e36s in the 90's. Our engine builder used to modify the head gasket so we could get more cooling to cylinders 5 and 6.
 

RSL

Sergeant
Aug 11, 2017
275
#30
As for, "if someone would by now"... The e36 and e46 M3 are 23 and 17 years old respectively and there are still products being developed for those, albeit slower these days of course. The N54 is only 11 years old, young in the world of aftermarket development and an infant in the track world. Go to a NASA, BMWCCA, Jeffapalooza, Chin, etc event and you will be hard pressed to find a an N54 based car, they are dominated by e30s, e36s and e46s. The track world is a HUGE untapped market for N54 evolution. What I mean by all this is that the cooling system of the N54 needs work for track guys, current solutions just don't cut it and there is much room for improvement in my opinion.

There should be a setting in MHD called "Track Mode". Basically run the water pump full speed at all times and run MAP thermostat open fully at all times. Before you load your car on the trailer, or when you get to the track if you drive there, load MHD "Track Mode" then when done with the weekend load street mode back and carry on.

The current MHD setting for "Race Mode" states: Coolant high + kft 80c(85c / 80c Stock) (This mode is activated at full throttle) Amb threshold for high + kft 27c (37c Stock)

Look at the histogram below from a lap on a track. You are at less than half throttle 38% of the time (braking zones and throttle modulation coming out of the turn). And there are plenty of track events through the season where there are sessions below 27c ambient temp. So based on this, when in "Race Mode" you are not targeting KFT at all times. Obviously Race Modes of normal and high try to target 85c as well which is great. But what is the DME doing when it switches between modes? Does it momentarily slow the pump down? I don't know. This is why I tagged @jyamona to see if he could enlighten me/us on the details of the logic as maybe i'm miss understanding it. This takes me back to the KISS. Remove without a doubt, the waterpump or thermostat fluctuating and just run them full speed and full open respectively.

Clearly a "Track Mode" can be accomplished with the XDF approach so maybe its a moot point, but it sure would be nice to have it as a setting in MHD!



View attachment 20382
Based on my experience, it's not just at WOT, but maybe they're seeing something in the code that I don't know. I'm not positive about it, so I never questioned the WOT statement, but has never seemed accurate to me. Only reason I'm not sure is because technical docs indicate load/how the motor is being operated as a factor (doesn't specify WOT), but logs of mine above are clearly in High+KFT and are solely PT or completely stopped/idle. Done both with and without the A/C on, so it's not a factor for load.

If you're not just running an OTS map, the cooling mode settings can be dialed in for exactly what you need/want for actual end output after some on-track testing. If you're using flash-time options, you're stuck with what they're writing though. In the meantime, I'd just give their default Track option a go at the next track outing and see what shakes out. Keep in mind, it would still need to be over ~72F ambient to activate on track mode.

I haven't spent much time at the track in forever, but agree, N54 cars don't seem a popular choice for those that do race. Between limps modes and driveline/chassis, E36/46 M3 would be my choices above N54/E9x as well. E92 M3 would even be down the list, felt like a boat to me, but still vastly more stable than non-M E9x's....and E9x Ms are also prone to limp mode issues on track. I certainly applaud anyone that does use an N54 car though, somewhat in a class by itself.

It is measured as the coolant comes out of the head at its hottest point. The N54 has two hot coolant outlets, one goes to the radiator (radiator hose) and the other (thermostat hose) straight to the thermostat. The hot coolant in the thermostat hose triggers the thermostat to open which then allows coolant to flow through the radiator, IE through the radiator hoses.
OK, that's what I thought, so do keep in mind it will be warmer than stat. BMW seems to have a history of running ~192F thermostats, and maybe just slightly cooler on some Ms, regardless of where the final managed temps "normally" run.

I just would like to add another point, which actually stemmed from @[email protected] in a conversation on the phone yesterday.

BMW designs are significantly compromised by constraints, namely emissions. Look at the PCV system - hardly performance oriented. The headaches in the cooling system come from emissions; otherwise the motor might always be kept at VE. Instead it is often targeted to run higher ... why ... emissions. So for target street use, that is up to around ~230°F, which in practice would be stoplights, et cetera. The closed loop control system - variable tstat, water pump, and radiator fan, with corresponding sensors and likely feedback from usage (TPS, load, ...) and while navel gazing, likely predictive targets for desired emissions profiles (and performance VE profiles we assumed) - well this ain't the old school two-stage radiator fan switch, a churning mechanical water pump, and a temperature sensitive tstat spring assembly. I probably have some of the details wrong, but I believe the gist is directionally correct (and feel free to say otherwise!)

I think it is a mistake for track guys to conclude their car is fine if they can throw parts at it and keep it from entering limp mode. The car is not a VE, nor was it designed to run full tilt for 30+ minutes at a time at sub-limp mode temperatures.

I agree with @[email protected]'s perspective - the N54 is 11 years young, at least from the lens of traditional BMW model development in the aftermarket. I'm enjoying reading everyone's input on this thread!

Filippo
Yeah, entirely too much crap on cars these days, but my money is more on them doing everything they can for MPG numbers for the masses while maintaining emission standards. If it weren't for emissions/fuel, I guarantee we'd have stratified mode here too in the name of +0.5mpg ratings lol

Happy Turkey Day!!
 

[email protected]

Specialist
Platinum Vendor
Jun 4, 2018
75
#31
I haven't spent much time at the track in forever, but agree, N54 cars don't seem a popular choice for those that do race. Between limps modes and driveline/chassis, E36/46 M3 would be my choices above N54/E9x as well. E92 M3 would even be down the list, felt like a boat to me, but still vastly more stable than non-M E9x's....and E9x Ms are also prone to limp mode issues on track. I certainly applaud anyone that does use an N54 car though, somewhat in a class by itself.

OK, that's what I thought, so do keep in mind it will be warmer than stat. BMW seems to have a history of running ~192F thermostats, and maybe just slightly cooler on some Ms, regardless of where the final managed temps "normally" run.

Yeah, entirely too much crap on cars these days, but my money is more on them doing everything they can for MPG numbers for the masses while maintaining emission standards. If it weren't for emissions/fuel, I guarantee we'd have stratified mode here too in the name of +0.5mpg ratings lol

Happy Turkey Day!!
Yeah been doing e30s, e36s, e46s for so long i'm kinda done with them. To be honest, right now the 335i as a track car is way more appealing to me. The entry point is cheap and power is easy to get. To me the suspension is easy to solve. The hard part about this whole puzzle is the cooling and turbo longevity. We'll see.

Not sure what you mean by "warmer than stat".

As for "entirely too much crap"... that's why I'm bringing this to light. The cooling system of the N54 was NOT performance oriented at all, it was mass production street car oriented as @fmorelli said. This example comes to mind... BMW started using MAP thermostat with the standard e46s back in 2000. Lots of those sold globally, emissions was factor. However, their flagship motorsports car the M3 did not have MAP thermostat. There is a reason for that. They knew these cars were going to get driven hard on the street, used on tracks, etc. BMW even developed a 165F motorsport thermostat. In other words, fuel mileage and emissions wasn't a major design parameter therefore it was designed to run sub 190F at all times.
 

RSL

Sergeant
Aug 11, 2017
275
#32
Not sure what you mean by "warmer than stat".
Just to take into account that logged ECT will be higher than the incoming coolant. Incoming must be pretty cool for logged 160-170s ECT...it's either keep things really cool or it's flying through the head/block so fast, it's not picking up as much heat per cycle. My guess is it's just keeping things really cool since it was normal driving conditions.

I'm frankly quite curious how sport or track change temps on track compared to your previous data.
 
Mar 10, 2018
122
#33
Just to take into account that logged ECT will be higher than the incoming coolant. Incoming must be pretty cool for logged 160-170s ECT...it's either keep things really cool or it's flying through the head/block so fast, it's not picking up as much heat per cycle. My guess is it's just keeping things really cool since it was normal driving conditions.

I'm frankly quite curious how sport or track change temps on track compared to your previous data.
In my experience, what MHD track and sport mode does, compared to stock, is help during cool down laps when ambient temps and engine power exceeds the capacity of the cooling system installed. So in other words, if the cooling capacity is large enough for the ambient temp/power used for the day, you wont hit power reduction no matter the MHD mode. If not, then you extend the time you can hot lap after any given cool down lap if MHD track mode is enabled. This is because you start from a lower overall engine temperature if you used MHD track mode during the cool down laps. You will still hit the roof of course, just later.

Now one question is how to avoid hitting power reduction mode, and how to increase cooling capacity, another is if the set points (and limits) are set correctly for continuous hot lapping in the first place.
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#34
In my experience, what MHD track and sport mode does, compared to stock, is help during cool down laps when ambient temps and engine power exceeds the capacity of the cooling system installed. So in other words, if the cooling capacity is large enough for the ambient temp/power used for the day, you wont hit power reduction no matter the MHD mode. If not, then you extend the time you can hot lap after any given cool down lap if MHD track mode is enabled. This is because you start from a lower overall engine temperature if you used MHD track mode during the cool down laps. You will still hit the roof of course, just later.

Now one question is how to avoid hitting power reduction mode, and how to increase cooling capacity, another is if the set points (and limits) are set correctly for continuous hot lapping in the first place.
Thanks for that info @Asbjorn! Lets talk in terms of equilibrium, (what the coolant is during hot laps, not cool down laps) which is what we care about for track use. So in another thread (which I quoted in post #1 of this thread) you stated you have a CSF radiator, Stock cooling mode, and have an intercooler that does not interfere with airflow to the radiator. On a 63F day your peak coolant was 221F and on a 100F day peak coolant was 246F, both way too hot. So what you are saying is if you are in MHD "Race Mode" you still have the same peaks? In other words the "Race Mode" is not helping equilibrium?

For reasons I already posted about in this thread, we want coolant temps to be between 190F-200F at all times. So if those temps are not being obtained when in "Race Mode" then more work has to be done to bring temps down. The biggest factors of cooling are water flow and surface area of the radiator.

Water Flow: At 9000 l/h (150 l/m) the n54 water pump isn't too bad. Obviously there is WAY more to it than this but if you use the very crude method of flow in l/h should be 1/3 HP then that means the N54 water pump at full bore MAY be able to handle 450 HP.

BMW actually states in their literature designing the radiator frontal surface area was a challenge because of the required FMIC of the N54. Lets compare the surface area of the N54 radiator core to the e46 M3 S54 radiator core. N54 is about 323 in/sq with roughly a 1.6" core and the S54 about 373 sq/in with roughly a 2" core. A heavily modded S54 is lucky to see 320 WHP. A modded N54 (for track use) is likely putting out 400-500 WHP, way more heat through a significantly smaller radiator than an S54.

I say all this because before going down the path of bigger radiator or accessory radiators (like the 1M and 335is) the water pump (and thermostat) needs to be figured out. You can go and put a radiator the size of Texas in the car but if the water pump isn't flowing at it's max and the thermostat not open all the way then what's the point.
 
Mar 10, 2018
122
#35
Thanks for that info @Asbjorn! Lets talk in terms of equilibrium, (what the coolant is during hot laps, not cool down laps) which is what we care about for track use. So in another thread (which I quoted in post #1 of this thread) you stated you have a CSF radiator, Stock cooling mode, and have an intercooler that does not interfere with airflow to the radiator. On a 63F day your peak coolant was 221F and on a 100F day peak coolant was 246F, both way too hot. So what you are saying is if you are in MHD "Race Mode" you still have the same peaks? In other words the "Race Mode" is not helping equilibrium?

For reasons I already posted about in this thread, we want coolant temps to be between 190F-200F at all times. So if those temps are not being obtained when in "Race Mode" then more work has to be done to bring temps down. The biggest factors of cooling are water flow and surface area of the radiator.
Agreed. I am 90% sure that MHD "track mode" won't help keep the coolant at 190F-200F if ambient temps and/or power exceeds the capacity of the hardware. On the other hand, if the capacity is there (either due to lowered power or lowered ambient temps), then stock cooling mode will do that just fine. In other words, the track mode does not increase the cooling capacity, it just delays the problem, which may work for short stints (like qualifying in hot weather) or drag races.

I do not have any track logs with MHD track mode enabled with my current cooling setup. But from my experience running MHD "sport mode" with VRSF race FMIC (covering parts of the CSF radiator), I already know that if ambient temps are high, then coolant temps will increase at a rate comparable to iat at WOT on my car. In below log I am doing a pull in 3-4-5th gear during a 77F humid track day. Coolant temp starts at 203F and ends at 208F during the pull despite the MHD "sport mode" being enabled:

https://datazap.me/u/asbjoern/track-session?log=0&data=2-5-12-13-21&zoom=815-899&mark=914

On the other hand, here's a log with MHD "stock cooling" enabled with my current hardware setup as listed in the first post. Ambient temps were much lower (60F-ish). I did 10mins on track, however accelerator was +80% only 2% of the time (it was a very slippery day):

https://datazap.me/u/asbjoern/bq-v18-track-session-shanghai-tianma-10mins?log=0&data=2-5-22&solo=5

In this case coolant temps were hovering around 198-201F. This tells me a stock N54 is targeting around 200F when pushed. So whenever the coolant temp exceeds this level, it is probably because the cooling capacity of the hardware is exceeded. These are my assumptions at least.

As to your other comments, I am not sure if the DCT/auto coolant radiators has less engine cooling capacity compared to MT radiators for N54? Please keep in mind that my data points are for a DCT car, ie with the DCT/auto version of the CSF radiator, albeit with an aftermarket DCT oil cooler as well.
 
Last edited:
Oct 28, 2017
818
Monroe CT
#37
Agreed. I am 90% sure that MHD "track mode" won't help keep the coolant at 190F-200F if ambient temps and/or power exceeds the capacity of the hardware. On the other hand, if the capacity is there (either due to lowered power or lowered ambient temps), then stock cooling mode will do that just fine. In other words, the track mode does not increase the cooling capacity, it just delays the problem, which may work for short stints (like qualifying in hot weather) or drag races.

I do not have any track logs with MHD track mode enabled with my current cooling setup. But from my experience running MHD "sport mode" with VRSF race FMIC (covering parts of the CSF radiator), I already know that if ambient temps are high, then coolant temps will increase at a rate comparable to iat at WOT on my car. In below log I am doing a pull in 3-4-5th gear during a 77F humid track day. Coolant temp starts at 203F and ends at 208F during the pull despite the MHD "sport mode" being enabled:

https://datazap.me/u/asbjoern/track-session?log=0&data=2-5-12-13-21&zoom=815-899&mark=914

On the other hand, here's a log with MHD "stock cooling" enabled with my current hardware setup as listed in the first post. Ambient temps were much lower (60F-ish). I did 10mins on track, however accelerator was +80% only 2% of the time (it was a very slippery day):

https://datazap.me/u/asbjoern/bq-v18-track-session-shanghai-tianma-10mins?log=0&data=2-5-22&solo=5

In this case coolant temps were hovering around 198-201F. This tells me a stock N54 is targeting around 200F when pushed. So whenever the coolant temp exceeds this level, it is probably because the cooling capacity of the hardware is exceeded. These are my assumptions at least.

As to your other comments, I am not sure if the DCT/auto coolant radiators has less engine cooling capacity compared to MT radiators for N54? Please keep in mind that my data points are for a DCT car, ie with the DCT/auto version of the CSF radiator, albeit with an aftermarket DCT oil cooler as well.
The mt does have higher cooling capacity because it doesn't have the bottom of the core used for the tranny.
 
Jun 4, 2018
70
#38
Yea the point is the school of steady state in any dynamic system.

As the coolant gets hotter, the potential difference between the air and the coolant is larger, thus causing more heat flow. Heat flow is very non linear and I've found goes up significantly once you have a greater than 100 deg delta in temperature. Resistance to heat flow is the next limitation, this is dependent on what materials/liquids are used, and how much surface area you can expose (thickness of radiator, tube size vs fin size, surface area of radiator). Then next the ability to flow enough coolant.


So as heat flows in, and heat flows out, the temp of the coolant will rise as long as the heat flow in is greater than the heat flow out. Once the delta temp is high enough to ambient air given all the other variables, you'll reach steady state.

The point being, we know the cooling system of the N54 simply cannot flow enough heat out to keep a steady state of 200 deg F, especially on a hot day of 100 deg weather where you're just starting to hit the point where you really start to flow heat (greater than 100deg delta).

Glycol has a much higher resistance to heat flow than water, and a lower heat capacitance. Thus running pure water while at the track helps A LOT. I've not seen many people mention this so far. I know it sucks to change your fluid every track day, but its only 6 quarts.

Increasing air flow helps, so more exposed surface area (front bumper changes), better through air flow (hood vents) are good things. But as you've identified one of our biggest setbacks is simply the radiator its self. There's only so much space to deal with there as well.

If we really want to see a change in coolant temps (even after all the above) the real solution is going to be adding a second radiator that is of big size, as large or larger than the stock one. The only place I see being able to do that is in the rear of the car.

With an exhaust change so the mufflers don't take up so much space, there's space back there under the trunk for added radiators, way more than anywhere in the front. I still think with some good ducting and making piping go back there with say 2 smaller radiators that take the place of the mufflers (and heat wrapping the mufflers), then some good ducting, you might be able to reach your goal.


Putting in a FMIC that doesnt block the radiator is a great idea, so is using those oil radiators for coolant instead, like the ones from, evolution race works, on both sides (that's a decent increase in sq inches) and running them in parallel instead of in series. That's something I think would be an interesting test. Use the ducting they give with a similar (but maybe cheaper) set of coolers and run coolant in parallel through them rather than oil....
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#39
Thanks for the link Neil!

Wow that thread was 46 pages deep. Uggg.... while the last post was in 2016 the meat of the discussion ended in 2012. I took the time to run through every page in the hopes to pick something up. Basically lots of noise but picked out some interesting points noted below. My takeaway from the entire thread was everyone attempting to keep the car out of limp mode more so than trying to get the coolant to the appropriate running temperature.

Excerpts from this link...

CSF Radiator Review from oppositelock website:

He talks about hovering and peak coolant temps but unfortunately we don't get any info as to what he means. Is peak at the end of a straight? We also don't get any ambient temps for comparison either. Anyways, in stock form it clearly overheats at 230F peak with 13 PSI boost (Using a JB4). Then we get data after the CSF radiator install. Unfortunately it was not an apples to apples comparison as he ran with more boost (17 PSI) but with a blend of E85. That peaked at 210F, still too hot. For me, I do NOT want to have to run E85. Its a pain to deal as almost no tracks have it which means I would then have to travel with it.

This is interesting for those running an automatic trans:

"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!"


Max Cool Mode on JB4:

"Water pump and fan will run at 100% duty when water temperature is between 160 and 202 degrees F. At 203 degrees F the DME ignores the fan command but appears to continue to overrun the water pump. We'll keep working on finding a way to extend the fan range upward to make the feature more useful."

This was from 2011. I have not looked into where this ended up. Interesting that they were worked to run the pump at 100% but not sure I follow the logic of the rest of it. Assume it was a limitation they ran into. Regardless of where this ended up, I do not want to have to run a JB4. This goes back to my point of there should be an MHD "track mode" of run water pump and thermostat full speed and full open respectively at all times.

HP Autosport Radiator

There was some talk about an HP autosport radiator but I only see the Mishimoto and CSF radiator on their ecommerce site. Anyone know where this ended up?
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#40
If we really want to see a change in coolant temps (even after all the above) the real solution is going to be adding a second radiator that is of big size, as large or larger than the stock one. The only place I see being able to do that is in the rear of the car.
This is why I was asking earlier what happens if we remove the fan. @RSL said the following:

"FWIW, not sure on normal models with 600w fan, but dealer didn't fully plug my fan connector in after a service once (at the fan). No lights, warnings or codes for it. Temps remained normal for weeks in cool weather. First time I got stuck in traffic after it warmed up a bit, ECT went up to about 235F, pulled over and finally found that the fan wasn't on. Clicked it in, fan on, good to go."

So it appears you get no check engine light when the fan is not plugged in. I plan to do more research on this to confirm. My point is that If we remove that big a$$ factory fan we can then put a MUCH slimmer fan or potentially a pusher fan instead. This frees up a TON of space to work with a MUCH bigger radiator.

On a track car once you get over 50-75 mph the fan does nothing to help. At times when we are driving on the street and at stoplights, if we can keep the engine cooler with waterpump and thermostat tweeks, then we won't need such a big fan.
 

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