[email protected]

Corporal
Platinum Vendor
Jun 4, 2018
136
Water does transfer heat more efficiently than antifreeze, but I run it primarily 'cause it's less slippery if/when it gets on the track.

Neil
Doesn't matter if its water or anti freeze, both are slippery and will cause loss of traction instantly. The reason for running water is because it dries up quickly and without the need to use "kitty litter" aka quick dry. Coolant doesn't evaporate and requires "kitty litter".
 

SJ_1989

Corporal
Aug 7, 2018
111
Illinoisssss
Water has a higher specific heat than 50/50 mix (i.e. it takes more heat to raise the temperature of water by the same delta as 50/50 mix). You can bump up the flow rate with a 50/50 mix to compensate for the reduced performance.
 

fmorelli

Colonel
Staff member
Aug 11, 2017
2,114
Virginia
You absolutely cannot compare data from two different tracks.
Or two different cars. The front end of these two cars is so fundamentally different it's like comparing the cooling of a school bus to a VW bug. Programming and airflow management FTW.

After looking closely at the front end of a 1M all I could think was, thank you Jesus the Z4 front end got way more open space in its design. Completely different cars. Air flow management is a thing - not just for F1 cars.

Filippo

p.s. 1M is a badass car, don't get me wrong, but it's tight up front, with small openings!
 

Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
Alright guys... Let's just conclude that noone with a tuned N54 has managed to solve the coolant temp problem on hot tracks as of yet. I will return with new data when my larger radiator has been installed late april.
 

berns

Corporal
Jan 15, 2018
113
Or two different cars. The front end of these two cars is so fundamentally different it's like comparing the cooling of a school bus to a VW bug. Programming and airflow management FTW.

After looking closely at the front end of a 1M all I could think was, thank you Jesus the Z4 front end got way more open space in its design. Completely different cars. Air flow management is a thing - not just for F1 cars.

Filippo

p.s. 1M is a badass car, don't get me wrong, but it's tight up front, with small openings!
Definitely not a lot of space to work with. Going to be looking into ducting to better organize the airflow. Wondering if I'd be better off blocking the side ducts entirely to force all the air through the center. Run a slim and wide single oil cooler behind the kidneys, the smaller CSF intercooler and paired with the CSF radiator.

Here's my current setup with the VRSF monster IC.

Eb1DKXzl.jpg
 
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GotPwned

Lurker
Apr 3, 2018
12
I am an amateur when it comes to setting up cooling with our cars. I have my first track day next month and am looking to retrofit an oil cooler since my 07 car didnt come with one. I have two questions:

1. Should I run twin oil coolers with the OEM thermostat or a single longer oil cooler with the thermostat delete plate.

2. Is it possible to run twin oil coolers with a thermostat delete plate?
 

Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
I highly recommend getting a 105C thermostat no matter which oil cooler you go for.

As for oil cooler size I recommend something similar in size as the M4 oil cooler, or the one I use for my DCT. I probably wouldn't go with a twin setup due to oil pressure concerns. I run my second oil cooler with a pump as part of a semi dry oil sump system.

Next problem will be your radiator which obviously is much harder to solve.
 

Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
@jyamona Quick question. What would happen if one lowered the coolant temp threshold (yellow warning) to 110C and red warning to 117C where AC and power reduction starts to kick in?

I think it would really nice for track driving to have the BMW warning lamps work like this. I would want the lamps to come on earlier than the actual power reduction and limp modes kick in. Those I want to keep stock. Ie I just want to modify when the lamps come on, not when the car actually starts to pull power to protect the car.

Same for DCT. I normally keep my DCT cooler turned off for street driving, and only turn it on for track driving. It would be nice to know if the transmission temp ever went above say 105C when just driving on the street, because then I could turn it on well ahead of any actual overheating.


targets.jpg
 
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Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
Alright, Im ready to conclude that adding a huge auxilary radiator in front of the OEM radiator won't keep coolant below 100C at my car's power level.

This week, new aux radiator and oil coolers were installed as described here. Below is a log from four laps at Ningbo Circuit. Laps #1-3 were all 2m21 laps, and the fourth lap a bit quicker, but nowhere near my personal best of 2m10. Peak coolant was achieved on the 4th lap at 105C in 19C ambient.


I started to push harder on the following laps, but then my old brake pads checked out (as expected), so I wasn't able to push coolant any higher today.

Below is a youtube video of the third lap. It is a demonstration of what can be done when combining a cheap dashcam with MHD (running in foreground) and the free version of RaceChrono (running in background). Definitely missing brake pressure, and since it took more than an hour to synchronize everything up, you do not want to do it often... I can also see that the speed data is lagging with the phone GPS, so I used MHD speed instead. I have a 10hz external gps, but the app for that don't export logs, nor does it run in the background of MHD.

 

matreyia

Captain
Apr 19, 2017
1,078
Alright, Im ready to conclude that adding a huge auxilary radiator in front of the OEM radiator won't keep coolant below 100C at my car's power level.

This week, new aux radiator and oil coolers were installed as described here. Below is a log from four laps at Ningbo Circuit. Laps #1-3 were all 2m21 laps, and the fourth lap a bit quicker, but nowhere near my personal best of 2m10. Peak coolant was achieved on the 4th lap at 105C in 19C ambient.


I started to push harder on the following laps, but then my old brake pads checked out (as expected), so I wasn't able to push coolant any higher today.

Below is a youtube video of the third lap. It is a demonstration of what can be done when combining a cheap dashcam with MHD (running in foreground) and the free version of RaceChrono (running in background). Definitely missing brake pressure, and since it took more than an hour to synchronize everything up, you do not want to do it often... I can also see that the speed data is lagging with the phone GPS, so I used MHD speed instead. I have a 10hz external gps, but the app for that don't export logs, nor does it run in the background of MHD.

You are trying to stay cooler than 105°c (221°f) ?

That's normal operating temperatures for coolant. And you have those on track day? I would be more than happy with that. Depending on pump settings, that temp should fluctuate between 230°f and 195°f. Lower than than affects emissions and mpg.
 

Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
You are trying to stay cooler than 105°c (221°f) ?

That's normal operating temperatures for coolant. And you have those on track day? I would be more than happy with that. Depending on pump settings, that temp should fluctuate between 230°f and 195°f. Lower than than affects emissions and mpg.
temps.jpg



When driving on track the car fairly quickly goes into high mode, targeting way below 100C. You can see it hitting as low as 85C during cool down laps. The only reason it is not staying below 100C all the time when I am pushing it on track, is because the car's power exceeds the capabilities of the cooling system (radiator + pump).

The car would never target such low temperatures on the road / when driving normally. That is, unless it is hot outside.

Below you can actually see the car go back into normal mode (+100C) as I exit the track.

 

matreyia

Captain
Apr 19, 2017
1,078
View attachment 26816


When driving on track the car fairly quickly goes into high mode, targeting way below 100C. You can see it hitting as low as 85C during cool down laps. The only reason it is not staying below 100C all the time when I am pushing it on track, is because the car's power exceeds the capabilities of the cooling system (radiator + pump).

The car would never target such low temperatures on the road / when driving normally. That is, unless it is hot outside.

Below you can actually see the car go back into normal mode (+100C) as I exit the track.

This information that you posted. Is that for the n54 engine or new model F and G series.
Also, I tested 'track' water pump settings and it behaved exactly as described...only going 185ºF when I repeated mashed the pedal. So I flashed it back to 'sport' pump settings because I don't drive like that normally. On 'track' settings, with a CSF radiator, the temps do not behave like normal settings, it goes pretty high very quickly, then when temps reach the threshold, it precipitously cools down within a minute or so. All the way down to 85ºc or 90ºc.
 

Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
This information that you posted. Is that for the n54 engine or new model F and G series.
Also, I tested 'track' water pump settings and it behaved exactly as described...only going 185ºF when I repeated mashed the pedal. So I flashed it back to 'sport' pump settings because I don't drive like that normally. On 'track' settings, with a CSF radiator, the temps do not behave like normal settings, it goes pretty high very quickly, then when temps reach the threshold, it precipitously cools down within a minute or so. All the way down to 85ºc or 90ºc.
It was a screenshot from the N54 technical pdf. The car seems to consistently enter the right cooling mode soon enough on track, so I do not use MHD sport or track modes. I have tried them when I was just running the CSF radiator alone, and they only delay the problem slightly. They might be useful for drag racing, but my car is neither tuned for that, nor have I ever actually been to a drag strip.
 

Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
The China GT championship is about to kick off at Ningbo Circuit and I was fortunate enough to get a detailed one-on-one walk-through with one of the Mclaren GT4 cars. All GT4 cars competing are essentially factory built track cars, with less power and budget compared to GT3. And I concluded that GT4 cars are essentially the ultimate track-day versions of their street equivalents. It is also the class where the M4 GT4 competes.

In terms of what @[email protected] and others are trying to achieve, I would say these are the cars to use for inspiration. These, as opposed to the likes of the M6 GT3 and Z4 GT3 that have nothing to do with the cars they were based on.

So here are my notes from the walk-through:
  1. Power: Similar to my car, 430-440ish. V8 turbo cars are detuned to match the lowest powered cars (apparently the Caymans)
  2. Weight: I forgot to ask, but around 1400kg (Weight is added so all cars have similar power-to-weight ratio)
  3. ABS: Stock. I was told that when driving in wet conditions, maximum braking is achieved by coming ever so slightly out of ABS, as opposed to with the GT3 cars that use racing ABS.
  4. Brakes: Surprisingly tame. Looked like any BBK. Apparently they only use endurance calipers for endurance racing, not for one hour races as they weigh more.
  5. Brake cooling: Both front and rear had two huge cooling ducts per disc. Looked absolutely ridiculous.
  6. Radiators: As a rough estimate the total radiator area was probably 2.5 times the size of our N54. The McLaren had an extra 52mm angeled radiator up front that the road car doesn't have. Unfortunately I did not get a chance to study the M4 GT4 in person, but I guess it is also fair to say that the stock M4 has double the (high temp) radiator area of an N54.
  7. Water cooler for intercooler: They mentioned that it sits in a vulnerable position on the McLaren. They had essentially run out of space for coolers, and commented that an NA engine would have been smarter as it doesn't need an intercooler.
  8. Data logging: VBOX, but no tire surface temperature logging.
  9. Suspension. They mentioned that different races have different minimum ride heights that the cars need to comply to. I was surprised how high they ride. I also learned that during wet races they sometimes remove the front sway bar completely.
  10. We didn't talk much about aerodynamics, and it didn't sound like it was a huge topic on these cars. The rear wing was adjustable but I couldn't get any details about what setting they used for this particular track. It seemed like it didn't matter much.
I think that was about it.
 
Last edited:

shushikiary

Corporal
Jun 4, 2018
117
There's an interesting idea.... especially combined with a hood vent... The condenser is also very loose in the car...

This starts to get silly in the amount of modification needed, especially because it would likely remove the emergency hood latch, so hood pins might be needed.

But, what if one was to change to a angled back radiator so it could be much longer, thus increasing its surface area. This is something I see a lot on race cars. It might require switching to a push rather than a pull fan setup.
 

gmx

Private
Dec 8, 2017
38
Does China GT follow SRO GT4 BoP or have their own BoP? The GT4 cars are "somewhat" different. Ie, the M4 has a true rear C/O. 718 Cayman CS have a Flat 6, whereas the roadgoing isn't even clear what Flat6 it's going to get. I like GT Racing, but it's not as rigidly homologated anymore. They control costs with pre-season testing (group of pro drivers test ALL cars) then apply BoP, then they keep adjusting BoP each weekend across all models regardless of how well the team is doing.
My guess is they have a minimum ride height to keep it "road relevant" and ensure floor aerodynamics do not have as much of an affect. I've noticed no complex rear diffusers or none at all on most GT4 cars.

I'm also considering a VBOX. I hate using phones/touchscreens esp with gloves. Syncing and the inability to multi-task on the those "dumb" devices is also inconvenient.

This also makes me somewhat question 1Ms/135 PPKv2 owners removing the aux radiator and it being pretty well accepted to replace with 2 large oil coolers. I get it, keep oil low and water/coolant has an easier time. That's thermodynamics. However, I can't help to think reducing coolant cooling capacity vs increasing increasing oil cooling capacity has to have some trade-offs.
I'm in the same boat as @berns , TQ 512 limit ruins my track days. Sometimes I barely get a clean lap in on a 30C day.

Edit: Anyway, I'm going to proceed with 2x 25 row setrabs with -10AN line and custom ducts.
Evo1 stepped intercooler and OEM main central radiator. Partially flushing coolant (it's probably 7 years old now) and concentrating more water, about 70/30. Rinse & repeat data, see how I go. Seems to work for ~6hr endurance cars here but once again their rules keep power low.
 
Last edited:

MDORPHN

Corporal
Jan 28, 2018
114
Does China GT follow SRO GT4 BoP or have their own BoP? The GT4 cars are "somewhat" different. Ie, the M4 has a true rear C/O. 718 Cayman CS have a Flat 6, whereas the roadgoing isn't even clear what Flat6 it's going to get. I like GT Racing, but it's not as rigidly homologated anymore. They control costs with pre-season testing (group of pro drivers test ALL cars) then apply BoP, then they keep adjusting BoP each weekend across all models regardless of how well the team is doing.
My guess is they have a minimum ride height to keep it "road relevant" and ensure floor aerodynamics do not have as much of an affect. I've noticed no complex rear diffusers or none at all on most GT4 cars.

I'm also considering a VBOX. I hate using phones/touchscreens esp with gloves. Syncing and the inability to multi-task on the those "dumb" devices is also inconvenient.

This also makes me somewhat question 1Ms/135 PPKv2 owners removing the aux radiator and it being pretty well accepted to replace with 2 large oil coolers. I get it, keep oil low and water/coolant has an easier time. That's thermodynamics. However, I can't help to think reducing coolant cooling capacity vs increasing increasing oil cooling capacity has to have some trade-offs.
I'm in the same boat as @berns , TQ 512 limit ruins my track days. Sometimes I barely get a clean lap in on a 30C day.

Edit: Anyway, I'm going to proceed with 2x 25 row setrabs with -10AN line and custom ducts.
Evo1 stepped intercooler and OEM main central radiator. Partially flushing coolant (it's probably 7 years old now) and concentrating more water, about 70/30. Rinse & repeat data, see how I go. Seems to work for ~6hr endurance cars here but once again their rules keep power low.
FWIW, we retained the auxiliary radiator on my 1M. It works together with a CSF radiator (in place of the stock unit). We also replaced the puny oil cooler with a large 34 row Setrab unit with an external 215F Improved Racing thermostat.

Neil
 
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Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
Does China GT follow SRO GT4 BoP or have their own BoP? The GT4 cars are "somewhat" different. Ie, the M4 has a true rear C/O. 718 Cayman CS have a Flat 6, whereas the roadgoing isn't even clear what Flat6 it's going to get. I like GT Racing, but it's not as rigidly homologated anymore. They control costs with pre-season testing (group of pro drivers test ALL cars) then apply BoP, then they keep adjusting BoP each weekend across all models regardless of how well the team is doing.
My guess is they have a minimum ride height to keep it "road relevant" and ensure floor aerodynamics do not have as much of an affect. I've noticed no complex rear diffusers or none at all on most GT4 cars.

I'm also considering a VBOX. I hate using phones/touchscreens esp with gloves. Syncing and the inability to multi-task on the those "dumb" devices is also inconvenient.

This also makes me somewhat question 1Ms/135 PPKv2 owners removing the aux radiator and it being pretty well accepted to replace with 2 large oil coolers. I get it, keep oil low and water/coolant has an easier time. That's thermodynamics. However, I can't help to think reducing coolant cooling capacity vs increasing increasing oil cooling capacity has to have some trade-offs.
I'm in the same boat as @berns , TQ 512 limit ruins my track days. Sometimes I barely get a clean lap in on a 30C day.

Edit: Anyway, I'm going to proceed with 2x 25 row setrabs with -10AN line and custom ducts.
Evo1 stepped intercooler and OEM main central radiator. Partially flushing coolant (it's probably 7 years old now) and concentrating more water, about 70/30. Rinse & repeat data, see how I go. Seems to work for ~6hr endurance cars here but once again their rules keep power low.
I run 2x25 setrabs, but one is with a separate pump to oil pan to avoid affecting oil pressure too much. If you are going custom ducts you could consider even larger setrab sizes. See my comment to Niel below.

Running only oem main central radiator won't be enough even if you run 100% water.

As a general comment I have never ever had power reduction due to high oil temps on my car running two oil coolers. Highest I have seen is 140C which is still far from the power reducing setpoint (147C). I have had power reduction due to coolant reaching 118C with just the CSF radiator though. So I would say running an upgraded stock location oil cooler is all you need at first. All other efforts should be put towards coolant cooling and then finally use whatever space is left for an FMIC (for MT cars anyway). If no space left, consider water injection. It makes no sense to me that the 1M guys remove the aux radiator to cool oil. Instead it should be upgraded significantly.

As for the VBOX it is certainly nice. Yesterday I finally decided to order the AiM Solo 2 DL. I will use it to display coolant temp, split times and have the LEDs indicate if I am ahead or behind based on my predicted laptime. Later it is easy to upgrade with a smartycam as well.

FWIW, we retained the auxiliary radiator on my 1M. It works together with a CSF radiator (in place of the stock unit). We also replaced the puny oil cooler with a large 34 row Setrab unit with an external 215F Improved Racing thermostat.

Neil
Im impressed you managed to fit that 34 row unit. I literally just downsized to 25 rows because my old cooler was a bit too tall for the forward location I use. I guess the ducting etc is different on a 1M. It would take a huge custom duct to use a rearwards positioned 34 row on mine.

Anyway if you managed to fit a 34 row oil cooler on the passenger's side, you might also be able to fit a 34 row on the driver's side to use with coolant. I would certainly do that if it wasn't because I already had another 25 row oil cooler on that side.

There's an interesting idea.... especially combined with a hood vent... The condenser is also very loose in the car...

This starts to get silly in the amount of modification needed, especially because it would likely remove the emergency hood latch, so hood pins might be needed.

But, what if one was to change to a angled back radiator so it could be much longer, thus increasing its surface area. This is something I see a lot on race cars. It might require switching to a push rather than a pull fan setup.
Agree - would be good to make a V with an FMIC and radiator in a custom box. Not really feasible though.
 

gmx

Private
Dec 8, 2017
38
FWIW, we retained the auxiliary radiator on my 1M. It works together with a CSF radiator (in place of the stock unit). We also replaced the puny oil cooler with a large 34 row Setrab unit with an external 215F Improved Racing thermostat.
Neil
Forgot to mention, picked up one of those thermostats too. And a 185F element just in case I want to experiment with it.
On my setup, we don't really run outside of the efficiency island on OEM turbos for the sole purpose of keeping heat rejection / IAT and motor safe.
I ran out of channels to log coolant but the rest are pictured in imperial units as well for easy viewing (why do units reset on MHD???)
26890


You can clearly see Tq limit 512 which is 117C coolant...
Was a 30-33C day, the max speed we reach on this circuit is about 195km/h, avg speed 115km/h. Not a fast circuit by any means to make use of ramming more air in existing duct and bodywork.

Completely OEM cooling setup (1M, 135i PPKv2). Fresh oil, probably still on factory coolant fill. THe car barely lasted 2 consecutive laps. Just like Berns, last corner on a good lap, no warning on dash, nothing about the impending doom. And on the contrary to "bam", no power on exit.

You've got to post pics of the 34 row. I don't see how it would fit? It's already tight including running lines with the series 6, 25 rows. The top of the core is very close the radiator support where the headlight sits. and the custom ducts have to be bent to shroud it properly. We also open the wheel liner to exhaust heat into the well. The tyre is close, very close...
 
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Asbjorn

Sergeant
Mar 10, 2018
284
Europe, based in China
Forgot to mention, picked up one of those thermostats too. And a 185F element just in case I want to experiment with it.
On my setup, we don't really run outside of the efficiency island on OEM turbos for the sole purpose of keeping heat rejection / IAT and motor safe.
I ran out of channels to log coolant but the rest are pictured in imperial units as well for easy viewing (why do units reset on MHD???)
View attachment 26890

You can clearly see Tq limit 512 which is 117C coolant...
Was a 30-33C day, the max speed we reach on this circuit is about 195km/h, avg speed 115km/h. Not a fast circuit by any means to make use of ramming more air in existing duct and bodywork.

Completely OEM cooling setup (1M, 135i PPKv2). Fresh oil, probably still on factory coolant fill. THe car barely lasted 2 consecutive laps. Just like Berns, last corner on a good lap, no warning on dash, nothing about the impending doom. And on the contrary to "bam", no power on exit.

You've got to post pics of the 34 row. I don't see how it would fit? It's already tight including running lines with the series 6, 25 rows. The top of the core is very close the radiator support where the headlight sits. and the custom ducts have to be bent to shroud it properly. We also open the wheel liner to exhaust heat into the well. The tyre is close, very close...
Thanks for sharing this data point. Sounds exactly like what I experienced when I was only running the CSF radiator in 35C. My M135i buddy experienced the same with stock cooling. The first thing you notice is AC being reduced, and next goes the power. I am looking forward to see if I can get the coolant that high again also with my current setup.

As for the thermostat, even the M4 GT4 uses a completely stock one.

@MDORPHN any pics of the 34 row cooler install?
 
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