What if we had a coolant temp gauge and not an oil temp gauge? (A call for more coolant cooling!)

Jeffman

Major
Jan 7, 2017
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Imagine if our N54 cars had a coolant temp gauge instead of an oil temp gauge...

I suspect the N54 community originally got all bent out of shape over oil temps because we were given an oil temp gauge instead of a coolant gauge. And with stock oil temp being set to the "astonishingly high" 240F what else were we to do but cry "That's crazy stupid high oil temp, WTF BMW?!?", leading BMS et al. to create inexpensive ways to keep oil temps lower like BMS' relatively simple oil diverter valve as well as ER's popular and more complicated oil cooling solutions like its single "Sport" auxiliary oil radiator and dual "race" oil radiator kits. These all seem to work fine for what they are designed to do, but others on this forum have noted that 240F oil temps are desirable for daily driving, emissions and fuel economy. But the situation is quite different for autocross and HPDE type track events during which our beloved N54s are pushed hard constantly for 20-30 minutes and limp mode inevitably ensues. Psychologically I think we all believe limp mode is triggered by high oil temps simply because that's the guage we stare at in the dash. I suspect if we were given a coolant temperature gauge instead then seeing coolant temps climbing greater than 300F would instead have hightened our awareness much earlier towards creating better coolant cooling solutions. We now know that both high oil temps (>300F) and high coolant temps (>250F) will cause limp mode. Indeed, the BMW engineers realized the coolant cooling deficiency in the N54 and subsequently designed the PPK system (larger fan and auxiliary coolant radiator) for reducing coolant temps, much like the way they added the oil cooler in 2007 having seen the deficiencies of the first N54-powered 335i cars produced in 2006. While many on this forum would probably argue that the PPK system is under-designed for real track work, I find it interesting that the BMW engineers didn't also include an upgraded oil cooler with the PPK system.

I think we should pay more attention to mods for lowering coolant temps. We now know that coolant temps above 250F are a major trigger for the DME to pull power and limp mode. And excessive coolant temps are especially a concern for AT cars like mine in which the engine coolant system is integrated with the ATF coolant system such that ATF temps tend to equilibrate with coolant temps after about 25 minutes or so daily driving. Indeed, just 10 minutes of spirited driving after warm-up caused both my ATF and coolant temps to quickly reach 220F last weekend (85F ambient). While my BMS oil diverter valve helped to keep oil temps under 245F during this 10 minute sprint, I'm sure the oil temps would have quickly exceeded 250F in this short time without it. A 10-minute cool-down period driving under low load quickly brought down oil, coolant and ATF temps, to 230F, 200F, 195F, respectively.

So I'm now wondering: Does there exist a quality-kit for auxiliary ATF cooling in the driver-side front bumper, much like the ER Sport Oil Cooler in the passenger-side wheel well? Ideally the auxiliary ATF cooler would work in parallel with the current ATF/ coolant radiator heat transfer system in place. I would then be staring a lot more at my coolant temp and ATF temp gauges (thanks to MHD).

[EDIT: Justin pointed out the correct "red zones" for oil temp and coolant temps. I adjusted the above text, accordingly. Thank you, Justin. I don't think it affects my conclusion that auxiliary coolant/ATF cooling is probably equally important as auxiliary oil cooling.]
 
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doublespaces

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Oct 18, 2016
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You asked why they didn't create an upgraded oil cooler. The answer to that is likely related to the fact that the ppk radiator core and the oil cooler cores are exactly the same, so they didn't have a design to upgrade to.

Regardless, the ppk radiator core is not good at all. It can't get my atf temps below 180 cruising on the freeway with air going through it. I've done exactly as you are asking, ppk radiator into an atf cooler.

I'm trying to swap it for a setrab but the issue is that the fittings exit on the top side, and the brake duct needs removed. Some people are okay with that while others are not.
IMG_20170819_172105.jpg
IMG_20170819_170218.jpg


Also I get to look at my oil and coolant temps, I run a manual transmission csf radiator:
received_1624387504247075.jpeg
 

Jeffman

Major
Jan 7, 2017
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You inspire me!
I didn't realize the performance steering wheel reported those temps. Does this mean your MHD iDrive display project is on hold?
Let's get some data about the effectiveness of those skinny brake ducts and make an informed decision. I'm sure somebody by now placed thermocouples down in there and on the brake dust shields to see whether those ducts are effective at speed.
 

doublespaces

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Oct 18, 2016
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You inspire me!
I didn't realize the performance steering wheel reported those temps. Does this mean your MHD iDrive display project is on hold?
Let's get some data about the effectiveness of those skinny brake ducts and make an informed decision. I'm sure somebody by now placed thermocouples down in there and on the brake dust shields to see whether those ducts are effective at speed.

When MHD Bluetooth comes out, I'll finally have all the information I could want. AFR, ATF Temp, Boost, etc.
 

Jeffman

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Jan 7, 2017
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My limited research suggests that our brake ducts just blow air on the tires and don't affect the brakes. Apparently having proper duct hosing attached to an opening on the brake shield housing to properly direct air to each front brake rotor will have a real effect. Pegasus Auto Racing Supplies looks to be a good source for hosing, connectors, in-line blowers etc:
https://www.pegasusautoracing.com/advcat.asp?CategoryID=BRAKEDUCT
Here's a DIY for an M3 where I found that link to Pegasus:
http://www.m3post.com/forums/showthread.php?t=316897

Question is with larger Setrabs installed on both sides would there be a good location (fog housing hole?) and room to install the brake cooling hose?
 

dyezak

Major
May 4, 2017
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My limited research suggests that our brake ducts just blow air on the tires and don't affect the brakes. Apparently having proper duct hosing attached to an opening on the brake shield housing to properly direct air to each front brake rotor will have a real effect. Pegasus Auto Racing Supplies looks to be a good source for hosing, connectors, in-line blowers etc:
https://www.pegasusautoracing.com/advcat.asp?CategoryID=BRAKEDUCT
Here's a DIY for an M3 where I found that link to Pegasus:
http://www.m3post.com/forums/showthread.php?t=316897

Question is with larger Setrabs installed on both sides would there be a good location (fog housing hole?) and room to install the brake cooling hose?

The brake ducts eliminate the negative pressure zone in the wheelwell. And the way the vanes in the disks work it sucks in air from the center of the disk around the hub and spits it out around the edge of the disk near the wheel/rim and the heated air gets pulled out of the wheel. So yes, the ducts are extremely effective in doing what they were designed to do.
 

doublespaces

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Oct 18, 2016
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BTW, thanks to @Dusty Waterfall I spent some time and came to the conclusion I'm going to try and squeeze a fan into my setup. In order to retain the cooler ducts, I'm going to make a bracket that pushes the core forward a couple inches to make room for a puller fan behind it.

2x Spal 4" Fan: http://amzn.to/2in6taP
Derale -8AN Thermoswitch: http://amzn.to/2g3aGiY
Mishimoto Dual pass cooler: https://www.mishimoto.com/dual-pass-oil-cooler-small.html

The cooler may be too tall, the top mounting points may need ground off to clear the headlight. It is skinnier than the Setrab series 6 leaving more room for a fan but less cooling capacity potentially. There is a little space between the core ducts and the bumper, so sucking that space up will hopefully leave enough room for a puller fan of 2" or less like the Spal units above.

EDIT: I went out and looked, there should be enough space for the Mishimoto cooler. Now, its just a matter of fitting the Spal fan.I'll have to take some more measurements with the wheel off later this week.
 

Traf

Sergeant
Aug 3, 2017
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If you live in a hot climate, just ditch the 50/50 coolant/water mix and go for 100% distilled water + additive. And or a csf radiator, should be more than enough cooling.
 

Traf

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Aug 3, 2017
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It does lower the boiling point of the mix, but only to 107°C for a 50/50 mix, that does not help much.
It also lowers the specific heat capacity, which results in higher temps. The viscosity increase also ultimately leads to higher temps as well, all while being harder to pump.
Antifreeze is primarily used for its lower freezing point and to fight oxidation, not for its cooling properties.
All of this to say that at a car operating temperature range, no coolant is better or more practical than water. Of course you need some kind of additive for oxidation prevention and pump lubrication.
 

9krpmrx8

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Nov 5, 2016
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San Antonio, Texas
The only issue with a fan (tried one on my drivers side oil cooler (it has two) on my RX-8 and it did nothing. It was a Derale, the SPAL 4" might be more powerful. But the fan will restrict flow at speed, the same way stock fans do on OEM setups and that why most of them have the doors in the fan shroud that open at speed.
 
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dyezak

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May 4, 2017
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One of the first for sale posts on this forum includes CF brake backing plates:

https://bmw.spoolstreet.com/threads/carbon-fiber-parts.482/

The question, is how can the stock brake duct be cut/routed back to an effective location, or perhaps even right to a backing plate. I hate the color of this hose though.

That backing plate design is horrible, you don't blow cooling air to the surface of a brake disk rotor, you blow it to the hub. The disk rotor has veins cast into the disk itself, the veins create an actual air pump when the disk is spun clockwise. This is known as a squirrel cage fan. Air enters in the center (the hub) and goes through the cast in veins that are arranged in a heat sink pattern, and exit at the circumference of the disk. Squirrel cage fans move lots of air, don't take the fan's air away from it and blow it at the surface of the disk, that's dumb. Use the internal veins that are designed as a heat sink for what they were designed for.

Or, if you can't visualize it, just look at real racecars with real engineers who are paid several hundred thousands of dollars a year just to keep the brake disks cool and see what they do. They blow the air into the hub...

brakes_e46_backingplate_installed_lg.jpg
 
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Kenjermen

Sergeant
Nov 6, 2016
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The IS version of these cars had a cooler like the oil one but for coolant, I used it and realized it wasn't that necessary my need for that location was a trans cooler being an automatic. Oil high temps are hard to combats on a turbo car. But yes trying to keep all fluid levels at a reasonable temp is a task for these cars and as of now it's a pic and choose battle. But I do recommend getting a CSF radiator this thing works and helped my car out a lot.
 
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V8bait

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Nov 2, 2016
495
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The coolant red warning comes on at 258F and pretty sure that's reduced power there, at 300 I think you'd be in trouble lol. The oil temp warning is 300F, red warning is at 320F (all of these can be changed).

Even in Texas I wouldn't run less than a 30% mix. In a place that gets cold I'd keep it at 50%. In Alaska I'd do 60-70% with block warmer. But sure you can run distilled water and an additive in the summer because racecar. Run that in the bikes but gotta remember to winterize them before winter or you're gonna have a bad time.
 
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doublespaces

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The only issue with a fan (tried one on my drivers side oil cooler (it has two) on my RX-8 and it did nothing. It was a Derale, the SPAL 4" might be more powerful. But the fan will restrict flow at speed, the same way stock fans do on OEM setups and that why most of them have the doors in the fan shroud that open at speed.
Do you know what the CFM was on the derale fans? Was it the fans that were worthless or the core itself?
 

Jeffman

Major
Jan 7, 2017
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BTW, thanks to @Dusty Waterfall I spent some time and came to the conclusion I'm going to try and squeeze a fan into my setup. In order to retain the cooler ducts, I'm going to make a bracket that pushes the core forward a couple inches to make room for a puller fan behind it. ...
EDIT: I went out and looked, there should be enough space for the Mishimoto cooler. Now, its just a matter of fitting the Spal fan.I'll have to take some more measurements with the wheel off later this week.
I had come across the B&M Racing coolers with integrated fans which may be of interest as well.
http://www.bmracing.com/products/70...i-tek-cooling-system-with-fan-590-cfm-rating/
 

Jeffman

Major
Jan 7, 2017
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And several types of automatic transmission fluid coolers described in B&M's marketing materials:
IMG_2509.PNG
 

Davidwarren

Corporal
Nov 6, 2016
203
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My limited research suggests that our brake ducts just blow air on the tires and don't affect the brakes. Apparently having proper duct hosing attached to an opening on the brake shield housing to properly direct air to each front brake rotor will have a real effect. Pegasus Auto Racing Supplies looks to be a good source for hosing, connectors, in-line blowers etc:
https://www.pegasusautoracing.com/advcat.asp?CategoryID=BRAKEDUCT
Here's a DIY for an M3 where I found that link to Pegasus:
http://www.m3post.com/forums/showthread.php?t=316897

Question is with larger Setrabs installed on both sides would there be a good location (fog housing hole?) and room to install the brake cooling hose?
The stock brake ducts are very effective. I can tell you a story anecdotally. I also chased oil temps first, and build my own oil cooler that lives in the driver side bumper area. I had to remove the driver side brake duct. My second track weekend with the new oil cooler, I ran through a half-used set of HT-10 pads, just on the driver side, and seized my brake caliper and bent the backing plate on the inside brake pad. The passenger side (with stock brake duct) still had probably 1/3 of the pad left. So yes, the stock brake ducts do work.

To address the rest of your concerns, since I do track my car at HPDEs rather frequently (have done 6 weekends this year already at Road Atlanta, NCM, Putnam Park, Autobahn CC, and IMS)-
My home built oil cooler works great, I use a setrab 625 (I think) running off the two plugs in the top of the oil thermostat with the stock oil cooler too.
I have the CSF rad running just distilled water and a bottle of WW during track season.
I have real brake ducts running off NACA ducts in the underbelly tray. Yes, they do dump a lot of air onto the rotor face, but they work well without resorting to a super expensive custom setup like the CF one posted above.
I still was killing my brakes on track, so I have Stoptechs on all four corners.

I have not hit limp mode due to temperatures at all for probably a year and a half.
 

Bnks334

Lieutenant
Dec 1, 2016
505
330
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New York
Lots of bad information in here. The cooling thresholds are well documented by now and can be found in many places. I uploaded the BMW N55 engine PDF here and an N54 specific PDF exists as well:

System Protection If the coolant or the engine oil overheat during operation, certain vehicle functions are influenced to the effect that more energy is available to the engine cooling system. These measures are divided over two operating modes:

• Component protection
- Coolant temperature between 117°C/242°F and 124°C/255°F
- Engine oil temperature between 150°C/300°F and 157°C/314°F
- Result: The output of the air conditioning system (up to 100%) and of the engine is reduced

• Emergency
- Coolant temperature between 125°C/257°F and 129°C/264°F
- Engine oil temperature between 158°C/316°F and 163°C/325°F
- Result: The power output of the engine is reduced (up to 90%)

The seconds part is that the DME controls coolant temps. Upgrading your radiator does nothing if you haven't also modified the cooling tables appropriately. MHD has released the cooling tables for both N54 and N55 and offers lowered thresholds for engaging more active cooling capacity for lower coolant temps:

- Coolant target flash option (Stock / Sport / Track)

Sport Mode:

Coolant normal 95c (106c 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 (37c Stock)
Amb threshold for high + kft 32c (42c Stock)

Track Mode (only for drag race application):
Coolant normal 90c(106c 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(37c Stock)
Amb threshold for high + kft 27c(42c Stock)

There is an ECO target (109°C stock) but it is not modified

N54 cars (twin turbos generate more heat) and DCT cars seem to suffer from higher temps. The solution hasn't been straightforward with people making claims of varying success with oil coolers, radiators, ATF coolers, or combinations of all three. At the end of the day, the stock 10 row oil cooler isn't all that effective on a tuned car. Upgrade to at least a 19row. Oil sheds heat less efficiently than coolant. With lowered coolant temps you'll still see oil temps climb without an oil cooler on track. You cant just throw a bigger oil cooler in the wheel well either it NEEDS to get air from the front fascia too. Same thing with a trans cooler. Radiator upgrade still seems necessary too since Race settings target 180f and I was still seeing 217f peak coolant temps at the end of the straight away (reasonable but not ideal)...

My 6MT N55 is perfectly fine at HPDE with stock cooling, modified tables, and lower cooling targets. I run straight water in the summer and switch back to 50:50 for winter. It makes a massive difference in cooling. The system is closed and is under 15psi pressure which greatly increases the boiling temp of the fluid in the cooling system. so no, you won't boil straight water + some type of additive like water wetter.

N55 Custom Cobb tune
PPK cooling tables (assumed to target lower coolant temps than stock)
88f and humid
http://datazap.me/u/banks334/track-d...oom=5722-31022

N55 Stage 2+ MHD OTS map
Cooling (race mode)
86f and humid
http://datazap.me/u/banks334/lime-ro...ata=6-19-20-22

My ghetto brake ducts:
* $25 2.5" shop vac hose kit
* 2x $5 shop vac large scoop attachments
* PFC-08 compound and RBF600 fluid

I'd write up a DIY, but people don't seem to like to see cheap stuff like this... All I did was cut the shop vac hose in half and trim the attachments down to fit my bumper. I then used large snips to cut out a hole in the heat shield for the hose to sit. I could have taken the heat shield off and made cut-out seamless, but I didn't feel like it was worth the extra effort. I just cut my heat shield right down the middle and then snipped out the 2.5" hole. Took all of about 15minutes lol

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