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

[barry@3DM]

Barry,

Keep in mind that the NA M motors have a MUCH lower heat flux than our engines do. Coolant flow into the N54 block is pretty symmetrical across Bank1/Bank2 , and the coolant passages in the HG actually get smaller as you move closer to cyl #1. I would imagine that, with the advent of modern FEA tools and unconstrained by using an all-new design, the NG6 motors should have pretty symmetrical coolant distribution across the cyls despite the lack of external cooling manifolds like in the S14/S54 above. FWIW the older Ferrari "Dino" V8s and V12s use a similar setup, its just the way things were done on race/hi-po engines back in the day before the advent of modern computer aided engineering tools.

Very interesting! You know... I've had several N54 headgaskets in my hand and never noticed that. Shame on me. (exposing the fact i'm not an engine guy lol) Absolutely agree, modern day stuff is so much different than the "old school" stuff. I assume all sorts of CFD was done on the block/head. Having said that, the CFD was done with a particular set of requirements, emissions and 300 BHP for example. We are now putting 1.5x to 2x the BHP through them in the aftermarket world so those requirements have now changed.

@Hydra Performance do you have any experience with the two different n54 blocks where some have the coolant channel between cylinders (early ones I think) and then some have no passage between them? Do you have a preference?

I think another thing that should be noted in regard to the cooling logic is that there is an "economy mode" that MHD does not cover. They leave it unchanged in their cooling setting changes.The car rarely goes into economy mode, from what I've seen. It's definitely not applicable at all to a discussion about tuning cooling tables for a track car. It's not like the car is dropping into economy mode on the track as you coast around a corner (this might be what the literature you quoted is referencing).

I can't speak on cylinder head coolant flow other than it's an open deck. So long as the channels are "tuned" well there shouldn't be too much hot spotting, like you noted. However, BMW did revise quiet a bit of the oiling and cooling channels on the N55 over the outgoing N54. The head-gasket is significantly different. I did notice there is quiet a bit of overlap of the gasket over certain channels. They must'v seen improvements to be made to have casted a new block and cylinder head... No one at Pirelli world challenge seems to have any issues racing the M235iR cars (n55s). You might be able to contact classic BMW or something and see what they have to say in regard to coolant DME logic on those cars.

Interesting note about the changes on the n55. I have Zero experience with those. But that is an excellent data point. I think I have seen those guys testing at NJMP before. I've been curious how the people running the M235Rs have fared with cooling. Seems like the n55 has less problems with cooling. The M235R clearly is going to have DME logic of a "performance" motor unlike our MSD81s. The guys racing the n20 motors have had all sorts of troubles. After going through many motors I think a mechanical water pump was part of the solution.

 

[Jake@MHD]

Hey guys, would like to help out here just a bit swamped at the moment. Will add when I can

 

[RSL]

I was going to say the same as Hydra. I wouldn't be surprised at all if N54s run only 8psi stock to even give them some chance of running inside thermal limits with a bit of headroom. 335is bumps stock boost only ~4psi peak for limited RPM range and time and they added the aux rad and +30% capacity fan just to help that.

WOT does not appear to be "the" trigger for KFT, but rather "a" trigger. Seems there are global conditions which trigger modes for any use and then conditions where mode changes are called (or disallowed) specifically, regardless of other parameters. This would explain why MHD indicates it's WOT, but also why it's clearly not only at WOT. From the info I've run across, sharp torque request increase switches to high+KFT and goes 100% on WP and stat heating.

It seems request related cooling adjustments are just a preemptive response to a known impending increase in thermal output, the mode or changes in pump/fan/stat shouldn't remain at that level because it's based on a transient change. I imagine there will be some increased minimums with more pedal no matter what, but it's not going to stay 100% WP/stat indefinitely going WOT for a few seconds. I've also read that Eco mode would only be used at idle or the lightest of loads and then only if allowed to enter that mode by other factors (oil temp, current ECT, previous running state, etc).

Forgot all about Testo until yesterday. Tested some params to get reacquainted with it. I logged more than are shown, but some IDs are more or less duplicates of others and some things left me scratching my head, like 0.4% KFT heating. Seems to be a conversion or rounding error, since some "100%" values are also 0.4% off (99.6%). You can just barely see at start, KFP PWM is at 100% and from my understanding (and common sense), DME checks that heaters are working and available at start. Also not sure on the relative WP BSD value, it may be a value based on something else or % of targeted since it stays essentially 100% the entire time. WP speed seems odd as well, but I'll see what they all do while I actually drive. There are a lot of params available through Ediabas, so will need to sort through them. Either way, it's working and we'll at least be able to log multiple params at once with something until Jake gets some free time

Just idle with some pedal in the middle...

 

[Hydra Performance]

Very interesting! You know... I've had several N54 headgaskets in my hand and never noticed that. Shame on me. (exposing the fact i'm not an engine guy lol) Absolutely agree, modern day stuff is so much different than the "old school" stuff. I assume all sorts of CFD was done on the block/head. Having said that, the CFD was done with a particular set of requirements, emissions and 300 BHP for example. We are now putting 1.5x to 2x the BHP through them in the aftermarket world so those requirements have now changed.

@Hydra Performance do you have any experience with the two different n54 blocks where some have the coolant channel between cylinders (early ones I think) and then some have no passage between them? Do you have a preference?

I would think that any effort made to equalize heat flux throughout the head/block in the name of emissions or economy or whatever, would be beneficial to maximum-performance as well. I suspect it is the overall throughput of the system, combined with its ability to shed heat, that appears to be a bottleneck for track use. Also keep in mind that the S55 cars have 2x auxiliary radiators + only a thin heat exchanger blocking the radiator to enable sustained track use @ 18-21psi and 7500rpm. The mechanical water pump also plays a role no doubt, as the B58 has moved back in that direction no doubt to help manage heat flux @ 26psi.

My 03/09 production block has the coolant channels between the cylinder liners that you refer to, they are 1.5mm wide and 7.5mm deep. I am currently refreshing an 07 block which originally did not have these, so I added subsequently added them. When you know that 90% of the heat released during combustion is concentrated in the topmost 10% of the cylinder liner, the decision becomes quite obvious...

 

[shushikiary]

I remember reading some old threads that the N54 has issues with the coolant channel between cyl's 5 and 6 boiling and causing issues....

Along with an aftermarket thermostat, if we had to we could just wire a switch to the pump to disconnect ECU controlled wires and just wire it straight to 12v, not sure if the ECU would get grumpy about that or not, but we could wire a resistor across the ECU controlled wires when we switch it if we had to, to fake out a load. Not sure how hard that would be for Jake to change that in the assembly.

I still think it would be an interesting (and fairly cheap/easy) experiment to modify the system to run coolant through 2x coolers and in the same place as the ER oil coolers.

 

[barry@3DM]

Ok so seems early blocks were no channel, later blocks were with the channel. I wasn't sure and hadn't done the research but quick RealOEM research does not distinguish anything in the From/UpTo date columns.

I definitely see the coolant channel being a cooling help for sure. Based on what @shushikiary said I could also see it being a detriment. I can see the coolant flow being so restricted through that channel that it flash boils and causes a hot spot. Below is a crack on cylinder 5 sleeve to the coolant channel next to cylinder 4. I will say that this was a result of detonation from a mechanical boost control component failure causing a 30+ PSI spike. So maybe can't blame it on a hot spot, but moreso as a weak spot. And when I say weak spot I mean it was the weakest point for a failure to happen from massive over boost, not saying it is a weak spot under normal operating conditions. Anyways, no opinions here, just observations.

The fact that BMW went back to a mechanical water pump with the B58 is testiment to the fact that we need to figure out what the water pump is doing on the N54. Very glad @jyamona is going to look into it when he has time! It as also interesting that they separated the turbo cooling system on the B58. To me that makes MUCH more sense, like @9krpmrx8 said he did on one his cars. I'm not saying that is the solution for an N54 based "track" car as it adds a lot of complexity. That to me would be more of a racecar thing.

To add to what @shushikiary said, I think this is possibly a two step solution process. Step 1 is we need to be able to make changes to the water pump, thermostat and fan without the DME freaking out. Step 2 (if even necessary) is once a solution has been derived, we go back to the DME and make it work with the solution.

For example, there are aftermarket performance/motorsport external thermostats and electric water pumps. The N54 pump is 9000 l/h and there are some that are 14000 l/h. They have their own controllers and everything to allow you to target temps, run for a predetermined time after the engine is cut off to keep coolant circulating, etc.

 

[RSL]

Still unpacking, but had time for some preliminary testing when I had to run out. Stock 335is INA0S bin, just some short 2nd gear pulls (too much traffic). Stock is from cold start to almost fully warm on the oil, KFT is stock bin with temp targets set to MHD track values and threshold set to 65F (it's about 70F out). That log was obviously higher starting temps after stopping/flashing.

High mode (cold start, oil not fully up to temp even by the end):
https://datazap.me/u/rsl/cooling-tests?log=0&data=1-2-3-4-6-8-10-12-13&zoom=14125-16353

KFT mode:
https://datazap.me/u/rsl/cooling-tests?log=1&data=1-2-3-4-6-8-10-12-13&zoom=2034-7904

- Temps are in Celcius
- I am somewhat convinced WP Performance (relative) is available power since it was 100% prior to even starting the car and never moved off 100% at any point. Some of the parameters that didn't log were WP voltage, WP current and mode. Not sure if they didn't get checked, aren't available or if I exceeded some count limit. Some are params are dups (fan DC/PWM) that I can skip and WP perf appears useless, except for maybe troubleshooting.
- WP speed appears to be a raw value, likely out of 250. BSD max flow conversion for the WP is 9000l/h at 250, but actual might extend further up to the 1 byte max (255 or 256). I've not seen anything over 250 logged for WP speed though, so even if it did go to 255/256, probably not going to show it or there's some offset. Either way, I would expect 250 is max and WP speed / 250 should be DC. I think I can add custom conversions to handle changing logged outputs to more readable values.
- As far as fan PWM goes, that 7.03% base reading is my fan not moving, so can only assume some conversion or offset issues on the data. I never saw higher than 46% fan PWM and that was after the warm start on KFT targets (colder), but KFT consistently had higher fan PWM than non-KFT mode (only increased fan 7->12% in response to WOT).

There are delays in response to WOT on both cooling methods (high and high+KFT), but KFT starts with the thermostat heated already and WP target increases appear quicker. KFT mode WP PWM target reached 100% (250) 4750-5200rpm in gear at WOT (actual speed plays catch up) whereas, high didn't get to 100% WP until after the gear was over/let off WOT. KFT also keeps the WP 100% for a long time after, but it does not appear to be in response to coolant or oil temps. Non-KFT mode cooling adjustments to WOT/high request states are delayed and turn off almost immediately by comparison.

Temps/targets are obviously in play as the DME is doing only what it needs to do in order to maintain head temp targets. With higher ambient or either generating more heat/reducing target temps, KFT mode should see everything reach 100% full-time (WOT or not). Of course, I'm not sure if there are any downsides like DME being pissed after a while with everything at 100% and still not reaching target, if it will drop to cold/warm-up tables, etc.

Will need to play around with targets more or switch to a high boost map to see how things respond, but, for now, what is happening is what I assumed: everything is active on KFT no matter what the torque request is and stat only heats in non-KFT modes in response to a high request.

High mode:

KFT mode:

 

[RSL]

Lowered kft mode target to 70c from 80c and WP speed is at 100% most of the time now just tooling around. Warm-up mode end is 55C stock (ECT motor side) and that is when the WP activates, but not sure if that temp cutoff effects anything else. It took oil *forever* to warm up this way. Did several more logs including several WOTs after this long ass drive and oil was still only 190F by the time I got home (30 minutes driving with probably 6-7 pulls after oil finally hit >165F).

https://datazap.me/u/rsl/cooling-test-70c-target?log=0&data=1-3-5-6-7-8-9-11-12

@barry@3DM, you'll probably just need to try it on track since I can't replicate that driving/extended thermal output on the street (or even get a clean 3rd gear here for that matter). I wouldn't expect any of this to stay remotely this cool for extended racing, but should definitely stretch out how long it takes the system to reach a thermal balance. It's clear that the stat/fan/pump will run up to 100% in KFT mode to keep things as close to target as they can. Stat finally makes it to 100% at the end of this log after a pull, stop, pull again, so I'd expect you'd hit the level for 100% WP/stat and more fan (if you use it) readily on track, probably even with the MHD 80C target. At that point, should just be a matter of generated heated vs. what can be exchanged with your current hardware/airflow since the cooling system will be max and stat allowing all the flow it physically can.

If the WP current draw is accurate, it's sucking up to 36.5A at full song.

 

[Jeffman]

View attachment 20971

Lowered kft mode target to 70c from 80c and WP speed is at 100% most of the time now just tooling around. Warm-up mode end is 55C stock (ECT motor side) and that is when the WP activates, but not sure if that temp cutoff effects anything else. It took oil *forever* to warm up this way. Did several more logs including several WOTs after this long ass drive and oil was still only 190F by the time I got home (30 minutes driving with probably 6-7 pulls after oil finally hit >165F).

https://datazap.me/u/rsl/cooling-test-70c-target?log=0&data=1-3-5-6-7-8-9-11-12

@barry@3DM, you'll probably just need to try it on track since I can't replicate that driving/extended thermal output on the street (or even get a clean 3rd gear here for that matter). I wouldn't expect any of this to stay remotely this cool for extended racing, but should definitely stretch out how long it takes the system to reach a thermal balance. It's clear that the stat/fan/pump will run up to 100% in KFT mode to keep things as close to target as they can. Stat finally makes it to 100% at the end of this log after a pull, stop, pull again, so I'd expect you'd hit the level for 100% WP/stat and more fan (if you use it) readily on track, probably even with the MHD 80C target. At that point, should just be a matter of generated heated vs. what can be exchanged with your current hardware/airflow since the cooling system will be max and stat allowing all the flow it physically can.

If the WP current draw is accurate, it's sucking up to 36.5A at full song.

All of this looks really promising for creating a durable N54-based track car that finally can avoid limp mode. Thanks for your good investigative work! As you show, keeping the water temps down does a great job at also keeping the oil temps down. Question: Are these runs using the OEM oil Tstat, or something else?

 

[Jeffman]

View attachment 20971

Lowered kft mode target to 70c from 80c and WP speed is at 100% most of the time now just tooling around. Warm-up mode end is 55C stock (ECT motor side) and that is when the WP activates, but not sure if that temp cutoff effects anything else. It took oil *forever* to warm up this way. Did several more logs including several WOTs after this long ass drive and oil was still only 190F by the time I got home (30 minutes driving with probably 6-7 pulls after oil finally hit >165F).

https://datazap.me/u/rsl/cooling-test-70c-target?log=0&data=1-3-5-6-7-8-9-11-12

@barry@3DM, you'll probably just need to try it on track since I can't replicate that driving/extended thermal output on the street (or even get a clean 3rd gear here for that matter). I wouldn't expect any of this to stay remotely this cool for extended racing, but should definitely stretch out how long it takes the system to reach a thermal balance. It's clear that the stat/fan/pump will run up to 100% in KFT mode to keep things as close to target as they can. Stat finally makes it to 100% at the end of this log after a pull, stop, pull again, so I'd expect you'd hit the level for 100% WP/stat and more fan (if you use it) readily on track, probably even with the MHD 80C target. At that point, should just be a matter of generated heated vs. what can be exchanged with your current hardware/airflow since the cooling system will be max and stat allowing all the flow it physically can.

If the WP current draw is accurate, it's sucking up to 36.5A at full song.

One more question: Is your car’s transmission manual or 6AT? If 6AT then maximizing the cooling system’s ability to remove heat may also reduce the need for an additional tranny radiator.

 

[RSL]

Stock 90k mile thermostat/WP on 335is (extra rad and 800w fan). The ideal solution would be to not have to run the thermostat heater to achieve coolest temp results, but not sure that's really an option. Stock stat without heating appears to limit temps to only 210F and uses limited WP/fan PWM, but it isn't enough in almost any circumstance other than commute type driving. To go any colder, stat needs to be in KFT (map) mode.

MHD Sport mode has good targets for daily, but maybe not the right mode activation threshold, depending on climate. People that run MHD sport or track enabled will find their cars running much warmer when ambients drop below 70-80F and KFT threshold is no longer reached.

If you're not on an OTS/locked map, it can all be dialed in easily.

Mine is DCT, uses the same exchanger/loop as the AT AFAIK. Moving the tranny to its own loop would surely take a load off the cooling system for track duty, but not sure if having to add another rad anyway wouldn't be better off leaving the exchanger the way it is and adding another rad to main system for additional capacity or run a small rad (or parallel pair) for the tranny separately. M3 DCTs use both the plate type exchanger part time and a fender mount rad the rest of the time. They still have temp related limp issues (especially with GTS TCU flashes), so I'm not sure a separate fender rad loop alone would be sufficient to carry the tranny heat. A pair of fender rads might.

 

[barry@3DM]

@RSL this is FANTASTIC research. Appreciate it very much!

I think it is safe to say that we don't need track testing to confirm any more about the water pump, in my opinion, @RSL's research confirms it's running full speed. That is not to say the waterpump is not the problem, there is a chance that it simply cannot flow enough LPH to properly cool the system but I think we can divert our focus over to the thermostat, radiator, and fan for now.

 

[barry@3DM]

Unless anyone has experienced different, we know that removing the fan does not throw codes or cause reduced power mode. This is based on @9krpmrx8's observation of his fan not being plugged in. This is good because removing the fan gives us a TON of room for a bigger radiator.

As for the thermostat, we cannot make any changes as the DME goes into reduced power mode (not limp mode) and throws an SES light. This is where @jyamona will hopefully be able to help. If we can prevent the DME from throwing a fault when it doesn't see the thermostat, then we can experiment with different thermostat designs.

I pulled a thermostat apart the other day to investigate modifying it. Looking for options

 

[matreyia]

I have never had over 2

(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)

I have never had over 260f on canyon carving days at 100f ambient...aggressive driving for 45 mins to 1 hr. Braking and acceleration to insane levels.

Dinan intercooler.
Dinan oil cooler.
Stock radiator
Afe intake magnum cai
Vrsf dp

I change oil every 3k to 4k. Every 3rd change I do a flush, then drive one tank on new oil, then change oil final time to help minimize any oil flush fluid remaining in the system.

 

[barry@3DM]

I have never had over 2


I have never had over 260f on canyon carving days at 100f ambient...aggressive driving for 45 mins to 1 hr. Braking and acceleration to insane levels.

Dinan intercooler.
Dinan oil cooler.
Stock radiator
Afe intake magnum cai
Vrsf dp

I change oil every 3k to 4k. Every 3rd change I do a flush, then drive one tank on new oil, then change oil final time to help minimize any oil flush fluid remaining in the system.

I assume you are talking about oil temps? I'm looking to keep coolant temps at 195F for extended track use on warm/hot days.

 

[matreyia]

I assume you are talking about oil temps? I'm looking to keep coolant temps at 195F for extended track use on warm/hot days.

Oil temps. Yes. Coolant never over 225f

 

[RSL]

Unless anyone has experienced different, we know that removing the fan does not throw codes or cause reduced power mode. This is based on @9krpmrx8's observation of his fan not being plugged in. This is good because removing the fan gives us a TON of room for a bigger radiator.

As for the thermostat, we cannot make any changes as the DME goes into reduced power mode (not limp mode) and throws an SES light. This is where @jyamona will hopefully be able to help. If we can prevent the DME from throwing a fault when it doesn't see the thermostat, then we can experiment with different thermostat designs.

I pulled a thermostat apart the other day to investigate modifying it. Because it is an external thermostat, it has two pistons to control water flow. I'll post up pictures tomorrow.

There are switches in the rom to set manual control of WP, stat and fan and then all of their PWM can be set to a fixed level (100%). A fan conversion is already defined and could be readily set 100% across the board within the logic.

Dropping targets is the workaround to force an increased response from the logic and does work, but would be easier just to set them where you want.

We'd need Jake to dig up WP/stat switches and manual PWM set point addresses though. I've sat down a few times to try following things through assembly without any luck.

 

[Bnks334]

https://datazap.me/u/rsl/cooling-test-70c-target?log=0&data=1-3-5-6-7-8-9-11-12

Thanks for confirming.

Again, don't forget about upgrading the oil cooler. You can get 230%+ more capacity out of a basic 26row bolt on and it does a massively better job than stock at keeping oil temps in check. Coolant only carries residual oil heat away from the head. Coolant's primary role will always be to keep cylinder head temps in check and not oil temps. Between a properly ducted oil cooler and an upgraded radiator you should be much closer to desirable operating ranges on track.

 

[matreyia]

Thanks for confirming.

Again, don't forget about upgrading the oil cooler. You can get 230%+ more capacity out of a basic 26row bolt on and it does a massively better job than stock at keeping oil temps in check. Coolant only carries residual oil heat away from the head. Coolant's primary role will always be to keep cylinder head temps in check and not oil temps. Between a properly ducted oil cooler and an upgraded radiator you should be much closer to desirable operating ranges on track.

Yep. Before attempting to go all out on your car, best practice is to make sure all components, no matter how hidden or seemingly insignificant, are upgraded. For me, on my car before it gets upgraded turbos:

1. Dinan oil cooler
2. Dinan intercooler
3. upgraded inlets/outlets
4. DP
5. CSF Radiator
6. PD Transmission Unit
7. M Factory LSD
8. LSD brace braket
9. upgraded transmission mounts
10. upgraded engine mounts
11. upgraded vacuum hoses - all
12. upgraded coolant hoses
13. stage 3 LPFP
14. Flex Fuel kit
15. Port Injection
16. PM4 LPFP upgraded controller
17. BL Coils and NKG Plugs
18. All gaskets done
19. Waterpump and therm done
20. All fluids and filters done
21. Carillo Rods
22. JE Pistons with upgraded rings
23. VAC bearings (main and rod sets)
24. dual catch can set up
25. Light race seats BRAUM
25. M-Performance Big Brakes Upgrade

THEN upgraded turbos and pan gasket.

 

[Bnks334]

25. Light race seats BRAUM

Sorry to thread jack, but, how do the BRAUM fit you? height/weight? do your shoulders land at a good spot above the belt openings?