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
#1
(Edit) I am trying to refocus this thread to DME temp control logic only. For those who are newcomers to this thread you may want to skip straight to post #51 and pickup there. Thanks! (/Edit)

Looking to get data points from those who have data logged their coolant and engine oil temps during extended track use. What I mean by extended track use is 20 to 30+ minutes continuous road course driving prefered. If for only a few laps, (Time Trial) please note. Also, please let me know what cooling mods you have to associate with those numbers.

Here is an example @Asbjorn posted in another thread:

MHD Setting: stock cooling
7in FMIC (downgraded from 7.5 to avoid covering part of the coolant radiator)
CSF coolant radiator
Additional engine oil cooler (part of semi-dry oil sump system)
95C oil cooler thermostat

100F day (AC on) - Ningbo Circuit
After one hot lap:
Peak coolant: 246F
Peak oil: 280F
Peak IAT: 167F

63F day (AC off) - Ningbo Circuit
Peak coolant: 221F (only monitored during the first 20min session)
Peak oil: 260F (definitely never saw 130C at any time today)
 
Last edited:

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Specialist
Platinum Vendor
Jun 4, 2018
75
#2
This question is for all those with N54 based DMEs...

Before I go and test my self, I'd like to save time and see what others have found happens when you disconnect the electric fan. Does the car go into limp mode?

On a similar note, has anyone tried running an aftermarket electric fan and if so what was needed to prevent any DME faults (if any).
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#3
More thoughts...

What exactly is the logic of "Track Mode" in MHD for cooling? @jyamona do you know the details of this? Much appreciated if you could help out here.

In the stock setup of the DME, my understanding is that coolant targets are based on throttle requests and vehicle speed. For example if you are sitting at a stop light it will target a high coolant temp to reduce emissions. However, when you go full throttle, the DME targets 194F as this is what they claim is best for volumetric efficiency. The MSD80/81 DME controls target cooling temps in 3 ways (correct me if i'm wrong) the flow of the water pump, the MAP thermostat, and electric fan speed. This is why I'm curious as to what "Track Mode" does, is it controlling all three or just one piece of the puzzle?

Some other side note topics of discussion...

The fan:
Stock is a 600 Watt fan. Anyone know the CFM? 800w for the 1M, same there, anyone know the CFM? Regardless, at 50-75+ MPH the fan is essentially out of the equation.

Thermostat:
The N54 thermostat is wax based with a heating element, IE Map based. In this case the wax will melt at a certain point open it's valve and allow coolant to flow through the radiator. Then if more cooling is needed, it will use the heating element to open the valve more for additional cooling. Does anyone know what the base wax opening temp is BEFORE the map takes affect?

I had a check engine light the other day for thermostat circuit. Found a faulty wire fix from a previous repair job from before I owned the car. Anyways, during the time the thermostat was disconnected the engine temp never went below 210F. My hunch is that this is the base wax opening temp but that is a total assumption.

Water Pump:
400 Watts - 9000 l/h. Anyone done any research or heard of options for a higher flowing H2O pump?
 
Last edited:

Torgus

Lieutenant
Nov 6, 2016
633
Boston
#4
I've never heard of a better water pump. The thing looks like a heart.

I would be more concerned with oil starvation than coolant temps...but that is just my uninformed fear.
 
Nov 5, 2016
259
San Antonio, Texas
#5
When my fan failed I was looking into alternatives ( I ran a dual FAL 480 setup on my RX-8) and talked with an engineer from Flex a lite and after I gave him the specs, he said they had nothing that could compare that would fit. He estimated that the stock 600W fan flows 3500 CFM and that the 850W fan flows around 4000CFM.

Now, I don't track but on the street sport cooling mode in MHD did drop my max temps during the summer (South Texas) about 10-15F in traffic. MY water pump is new, I changed it preventatively as running it more will surely shorten the life.

Another option I did in my last car (turbocharged RX-8) is to run a secondary radiator. That helped a ton and I also had my turbo on its own cooling circuit with a bosch coolant pump and its own reservoir and heat exchanger. I am not sure how effective the BMW secondary radiator is from the 335is but the whole kit is like $400.00.
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#6
When my fan failed I was looking into alternatives ( I ran a dual FAL 480 setup on my RX-8) and talked with an engineer from Flex a lite and after I gave him the specs, he said they had nothing that could compare that would fit. He estimated that the stock 600W fan flows 3500 CFM and that the 850W fan flows around 4000CFM.

Now, I don't track but on the street sport cooling mode in MHD did drop my max temps during the summer (South Texas) about 10-15F in traffic. MY water pump is new, I changed it preventatively as running it more will surely shorten the life.

Another option I did in my last car (turbocharged RX-8) is to run a secondary radiator. That helped a ton and I also had my turbo on its own cooling circuit with a bosch coolant pump and its own reservoir and heat exchanger. I am not sure how effective the BMW secondary radiator is from the 335is but the whole kit is like $400.00.

Great information! Thanks!

I'm familiar with the secondary radiator (from the 1M), it's not much help.
 
Aug 11, 2017
1,614
Virginia
#7
I've never heard of a better water pump. The thing looks like a heart.

I would be more concerned with oil starvation than coolant temps...but that is just my uninformed fear.
When car goes in limp mode on the track, one doesn't have to worry about oil starvation :sunglasses:.

Filippo
 
Jun 4, 2018
70
#8
I remember many older threads about similar things.

A few people have added larger oil coolers. I've added 2 oil coolers, both over 400 sq inches. I've found exactly what a few other posts have said, which is that adding the oil coolers doesn't lower my peak oil temps, but it does 2 things instead. 1. It lowers my coolant temps by about 10 degrees. 2. It makes the oil temps come back to normal MUCH faster than before.


I think the biggest thing you can do is put a CFS radiator in place of our stock one and run some water wetter, and/or run a much lower glycol solution at the track then swap back to a 50/50 for normal use.

As far as the ECU goes, there are a bunch of tables available in today's XDF's that you can change. You can change when the yellow/red warning temps are for both coolant and oil. You can also change the target temp of the system, as well as the PWM % for the fan based on how far off that target you are, and you can also change when different pump modes turn on. There's normal, high, and high + KFT.

For my self I set the car to stay in high + KFT any time the out side temp is above 50 deg F (basically on all the time when not winter), then set my target temp to 180 deg F. Then I adjust my fan PWM to turn on 20 % if the temp is above target by 5 deg C, then 40% by 11 deg C, and 90% by 18 deg C delta.

I find with those settings any time its below 80 deg F out she'll hold below 190 on the highway, but if it gets warmer than that she'll get warmer (between 190 - 200). On STUPID hot days when I'm on the highway at 75 mph but climbing a slow hill for 30 minutes essentially, on 105* days (note this is at altitude where its even harder to cool (5280 feet)) she'll get up into the low 220's just on the highway. And that's with 50/50 with water wetter, stock radiator. She used to get up into the 230's before I put the oil coolers in. And this is with ceramic coated manifolds and turbo's (GC lite 2.0's) with heat wrapped down pipes.

I know that's not exactly what you were looking for, but its all the info I could give you that I have.
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#9
I remember many older threads about similar things.

A few people have added larger oil coolers. I've added 2 oil coolers, both over 400 sq inches. I've found exactly what a few other posts have said, which is that adding the oil coolers doesn't lower my peak oil temps, but it does 2 things instead. 1. It lowers my coolant temps by about 10 degrees. 2. It makes the oil temps come back to normal MUCH faster than before.


I think the biggest thing you can do is put a CFS radiator in place of our stock one and run some water wetter, and/or run a much lower glycol solution at the track then swap back to a 50/50 for normal use.

As far as the ECU goes, there are a bunch of tables available in today's XDF's that you can change. You can change when the yellow/red warning temps are for both coolant and oil. You can also change the target temp of the system, as well as the PWM % for the fan based on how far off that target you are, and you can also change when different pump modes turn on. There's normal, high, and high + KFT.

For my self I set the car to stay in high + KFT any time the out side temp is above 50 deg F (basically on all the time when not winter), then set my target temp to 180 deg F. Then I adjust my fan PWM to turn on 20 % if the temp is above target by 5 deg C, then 40% by 11 deg C, and 90% by 18 deg C delta.

I find with those settings any time its below 80 deg F out she'll hold below 190 on the highway, but if it gets warmer than that she'll get warmer (between 190 - 200). On STUPID hot days when I'm on the highway at 75 mph but climbing a slow hill for 30 minutes essentially, on 105* days (note this is at altitude where its even harder to cool (5280 feet)) she'll get up into the low 220's just on the highway. And that's with 50/50 with water wetter, stock radiator. She used to get up into the 230's before I put the oil coolers in. And this is with ceramic coated manifolds and turbo's (GC lite 2.0's) with heat wrapped down pipes.

I know that's not exactly what you were looking for, but its all the info I could give you that I have.
Even though it is different than what i'm looking for it is fantastic info. I will definitely look into the XDFs.

In nutshell, I'm trying to figure out what the N54 cooling system is capable of during a long track session 30+ min, even with mods such as dual oil coolers and the CSF radiator. I'd like to see coolant run at no more than 200F on a warm/hot day (80F+). I'm wondering if anyone has been able to accomplish this?

I get that the N54 motors can run at higher temps such as 230F but this was designed to be done at low RPMs for emissions purposes. Using data aq, I ran a histogram on the throttle % and RPM over the course of a 20 min session on track. Throttle position was over 90% for 60% of the time. RPMs were over 5000 70% of the time. Running at 230F+ simply doesn't cut it for longevity in this scenario.
 
Last edited:
Jun 4, 2018
70
#10
I think that to stay sub 200 on a 90 + degree day, you're going to have to do something much more drastic.

I know our engine bay holds heat in like a mofo, putting vents in the right place (directly aft of the radiator especially) would likely help so the hot air doesnt then wash over the engine.

Other than that, putting in MUCH more radiator space is about it. You could make a completely custom system that puts a second radiator under the trunk by cutting the trunk floor out and putting ducts in to direct air across it.

Without doing something drastic like that (and maybe going to an aftermarket water pump), I'm not sure you'll be able to hit the 200 deg F goal.

Going to a dry sump oil system would also help A LOT.
 
Jan 28, 2018
49
#11
The car (my 1M) already has two small heat extracting hood vents and it'll shortly have a much larger one just behind the radiator. In addition, the MOTIV single turbo manifold, downpipes and hotside turbo housing are all White Lightning thermal coated.

In addition to the stock auxilliary radiator, it also has a 34-row Setrab oil cooler.

Neil
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#12
I think that to stay sub 200 on a 90 + degree day, you're going to have to do something much more drastic.

I know our engine bay holds heat in like a mofo, putting vents in the right place (directly aft of the radiator especially) would likely help so the hot air doesnt then wash over the engine.

Other than that, putting in MUCH more radiator space is about it. You could make a completely custom system that puts a second radiator under the trunk by cutting the trunk floor out and putting ducts in to direct air across it.

Without doing something drastic like that (and maybe going to an aftermarket water pump), I'm not sure you'll be able to hit the 200 deg F goal.

Going to a dry sump oil system would also help A LOT.
I realize sub 200F is going to be difficult and likely not attainable. From my experience and what I've seen of others posting about temps, keeping coolant temps under 230F seems to be difficult. This is why i'm hoping more people chime in on their temps on track and what mods they have done. I know a lot of people have done oil cooler upgrades such as bigger cooler in the OEM location, oil thermostat deletes, multiple coolers, etc. What I want to know is who has done what with the coolant radiator? Other than bolt on Mishimoto or CSF... I'm just trying to get data points.

I know hood vents will help but I'm hoping a solution can be found without it as I'm not keen on having hood vents on my street/DE car. For a dedicated track car/racecar sure, but that is another story.

As for much more radiator, this is why I was asking about the fan and what happens with the DME when its disconnected. In other words, with some work, perhaps a different fan will allow for a bigger radiator. That stock fan makes it tight at the front of the motor.
 

zcchen

New Member
Nov 19, 2018
4
#13
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
lap1.jpg
Lap 2
lap2.jpg
Lap 3
lap3.jpg
Lap 4
lap4.jpg
Lap 5
lap5.jpg
Lap 6
lap6.jpg
Lap 7
lap7.jpg
Lap 8
lap8.jpg
 
Last edited:
Jan 28, 2018
49
#14
FWIW, I replaced the stock oil cooler on my single turbo 1M with a 34-row Setrab, the largest heat exhanger that can be fit, and a 185 F Improved Racing thermostat. It's properly plumbed and vented.

It lowered my max oil temps on 90 F days at VIR from 290 to 265 F and it generally stays below 230 F.

Neil
 

RSL

Sergeant
Aug 11, 2017
275
#15
More thoughts...

What exactly is the logic of "Track Mode" in MHD for cooling? @jyamona do you know the details of this? Much appreciated if you could help out here.

In the stock setup of the DME, my understanding is that coolant targets are based on throttle requests and vehicle speed. For example if you are sitting at a stop light it will target a high coolant temp to reduce emissions. However, when you go full throttle, the DME targets 194F as this is what they claim is best for volumetric efficiency. The MSD80/81 DME controls target cooling temps in 3 ways (correct me if i'm wrong) the flow of the water pump, the MAP thermostat, and electric fan speed. This is why I'm curious as to what "Track Mode" does, is it controlling all three or just one piece of the puzzle?

Some other side note topics of discussion...

The fan:
Stock is a 600 Watt fan. Anyone know the CFM? 800w for the 1M, same there, anyone know the CFM? Regardless, at 50-75+ MPH the fan is essentially out of the equation.

Thermostat:
The N54 thermostat is wax based with a heating element, IE Map based. In this case the wax will melt at a certain point open it's valve and allow coolant to flow through the radiator. Then if more cooling is needed, it will use the heating element to open the valve more for additional cooling. Does anyone know what the base wax opening temp is BEFORE the map takes affect?

I had a check engine light the other day for thermostat circuit. Found a faulty wire fix from a previous repair job from before I owned the car. Anyways, during the time the thermostat was disconnected the engine temp never went below 210F. My hunch is that this is the base wax opening temp but that is a total assumption.

Water Pump:
400 Watts - 9000 l/h. Anyone done any research or heard of options for a higher flowing H2O pump?
Track mode was high+kft cooler target and lower threshold than Sport IIRC. They posted the specifics somewhere when it was released, but might've changed since.

You'd want High+KFT threshold set to a lower ambient temp than the lowest you'd see and, obviously, a cooler target, otherwise, you're only relying on the wax only IIRC. I think even in "high" mode it's a bit more water pump and fan, but thermostat is still wax regulated. KFT is map thermo, which you'd need to drop ECT below wax limits.

Not track, but may help with some info -- top screen below is a commute (about 12 miles) in 103F ambient in TX, totally stock cooling schemes, but hot enough ambient to reach the stock High+KFT ambient threshold (37C / 99F). ECT is mostly 175-185F and creeps at the end hitting stop/traffic/then parked idle. OCT peaked early in the log at 225F, but mostly 215-220F at speed. I've seen ECTs dip into the 160s on High+KFT on totally stock 335is cooling (800w fan + extra rad) with all panels/cowl in place. Not sure how it would translate on track at speed for an extended period, but it's obviously noticeably cooler than eco or normal modes. If you're first track day was "really" 100F, you might've been in KFT mode, but not sure with those temps. If your additional cooler is plumbed into the coolant system (on top of AT/DCT exchanger), it's giving the system even more work to handle.

Second chart is similar commute, but at ~90F ambient where it didn't reach High+KFT, but looked like high kicked in mid-way and can see the difference in temps compared to KFT. That log also tends to confirm the 210F minimum ECT with wax only.

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.

kft.png



kft2.png
 

RSL

Sergeant
Aug 11, 2017
275
#16
Found the release info for MHD cooling modes from mid-2017, might've changed since:

---------------------------------------------------------------------
The following changes were made:

Sport Mode
• Coolant normal 95c (104c Stock)
• coolant high 90c (95c Stock)
• Coolant high+kft 80c (85c / 80c Stock) (This mode is activated at full throttle)
• Amb threshold for high mode 27c (32c Stock)
• Amb threshold for high + kft 32c (37c Stock)

Race Mode (only for drag race application)
• Coolant normal 85c(104c Stock)
• Coolant high 85c(95c Stock)
• Coolant high + kft 80c(85c / 80c Stock) (This mode is activated at full throttle)
• Amb threshold for high mode 22c(32c Stock)
• Amb threshold for high + kft 27c(37c Stock)
 
Nov 5, 2016
259
San Antonio, Texas
#17
Yeah it's about the system as a whole. Are you guys running stock kidney grills and grills on the bumper? On past cars I have found that unrestricted air to the cooler, front and back helps. But of course that comes with its own drawbacks.
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#18
@RSL thanks for that! I remember this chart back when it was released. Last month was the first time I had a chance to do a back to back test of Stock vs Race Mode on a track. I wanted to look at the specs of Race Mode but the "N54 Manual" link on the MHD site was not working. Internet was not strong in the paddock so searching for it was a pain. During the session the poorly done thermostat wiring fix from before I owned the car failed and I was unable to get the comparison. Then it dropped off my radar at the time.

I assume the (only for drag race application) comment is so people don't run it full time for waterpump longevity?
 

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Specialist
Platinum Vendor
Jun 4, 2018
75
#19
Yeah it's about the system as a whole. Are you guys running stock kidney grills and grills on the bumper? On past cars I have found that unrestricted air to the cooler, front and back helps. But of course that comes with its own drawbacks.
The car I picked up has the basic 335i bumper. Plans are to swap over to M Sport or something similar when doing all the new heat exchanger work to allow for larger air inlets. Completely agree with the grills and the mesh stuff, they kill airflow. I have some ideas to test that will help prevent potential rock damage.
 

RSL

Sergeant
Aug 11, 2017
275
#20
@RSL thanks for that! I remember this chart back when it was released. Last month was the first time I had a chance to do a back to back test of Stock vs Race Mode on a track. I wanted to look at the specs of Race Mode but the "N54 Manual" link on the MHD site was not working. Internet was not strong in the paddock so searching for it was a pain. During the session the poorly done thermostat wiring fix from before I owned the car failed and I was unable to get the comparison. Then it dropped off my radar at the time.

I assume the (only for drag race application) comment is so people don't run it full time for waterpump longevity?
Probably a combo of water pump longevity, maybe thermostat longevity (heating elements) and efficiency. There's no real reason to run it that cold for just puttering around town, but can't imagine any would be impacted in a real noticeable way if it were. I was in KFT mode on stock cooling parameters for months at a time every year with 50 mile round trip commutes and the original water pump/thermo are still kicking at 90k miles. One year set the record for consecutive days of 100F+ (>70). Granted, it's not 365, but a good chunk of the years and long daily drives, often stuck in stop/go traffic, so everything has some substantial total time running in KFT mode by now. Especially for actual race car and not just "because race car", I personally wouldn't lose any sleep leaving KFT triggered all the time.
 

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