Asbjorn

Sergeant
Mar 10, 2018
292
Europe, based in China
So I went to chat with the racecar builder working on the 135i above, which is for a client. Basically they don't have any data on the car yet, as it still isn't running. But here are some key facts
  • Single rear mounted radiator with large underbody scoop
  • Stock water pump, thermostat delete, 38mm tubes, MoTeC ECU
  • System uses around 12L coolant
They are concerned if a helper pump is needed - only time will tell. The engine had something that looked like Zage 19T turbos and target is 600hp. Besides improved coolant cooling, they also moved the radiator to increase flow to the stepped FMIC.

Other comments from our conversation
  • To increase flow through the engine bay, do not open anything up below the windshield. It is a high pressure zone. A very common mistake. Better options are the sides behind the front wheels, or the hood area just behind the radiator (think M4 GT4)
  • Radiators in general do not benefit much from adding thickness past 50mm. (Probably also why my solution is not super effective)
  • The only option I have on my car is basically installing a new single radiator at an angle. Ie alot of custom work. But they were very surprised that I still have such high coolant peaks.
On a final note I also got to study this 1000hp drift car on saturday. It also had a rear mounted radiator with fans working 100% of the time:

956218311.jpg


458671382.jpg
 
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Asbjorn

Sergeant
Mar 10, 2018
292
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.
Here you go

mmexport1557913762339.png


One day, using slicks, I should be able to set a hotlap time on pair with the M4 GT4... one day...

More M4 GT4 pics

mmexport1557914264879.jpg mmexport1557914293133.jpg
 

gmx

Private
Dec 8, 2017
39
This is awesome, keep it coming.
Very interesting that the 718 Cayman is 20kg heavier and still earns 70kg ballast. Looks very well developed leap ahead from the 981.
 

Hydra Performance

Sergeant
Free Vendor
Jan 31, 2017
258
This is awesome, keep it coming.
Very interesting that the 718 Cayman is 20kg heavier and still earns 70kg ballast. Looks very well developed leap ahead from the 981.

Yet more proof, if any were needed, that FI > NA in terms of laptime performance for a given power/weight ratio...
 

Asbjorn

Sergeant
Mar 10, 2018
292
Europe, based in China
So a few more data points from yesterday. My friend and I participated in a track day at guangdong international circuit on an insanely hot sunday.

Ambient temp: 38C / 100F
Humidity: 65%

An N55 M2 won the time attack on Pirelli DMs. Set a time of 1.26 on the third lap. Half way through that lap the car gave a warning about high oil temperature in the cluster.
I also spoke to a guy in a 3.0 Z4 (N52). He saw peak coolant temp of 122C / 252F during his stint.

I did not do time attack, but instead participated in an 1h endurance race. My co-driver did qualification to get familiar with the car. He hit peak 119C / 246F coolant because I hadn't instructed him properly on the need for cool down laps. Iat peaked at 125F above ambient although I am now running a HD core. During the race we kept the coolant below 110C / 230F and iat below 70F over ambient by limiting the use of WOT at the end of the long straights. We only completed 55min of the race due to getting 30FF at the very end.

Here's the data. (if you switch logs you can also see the quali data):


1364855710.jpg


mmexport1558336995807.jpg


7a6cb0540b75810199380e6ced4bf1bb.jpg



On a related note it also looks like the M4 GT4 indeed uses the coolers listed on realoem for actual racing:

mmexport1558335069667.jpg
 
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Davidwarren

Corporal
Nov 6, 2016
120
Louisville
I got a big bump in cooling efficiency by removing my A/C. It was leaking in the cabin... But pulling the condenser from in front of the radiator and blocking off the openings that went to the OEM intake gets a lot of ambient air through the radiator. I also have a large hood vent right behind the radiator to pull hot air out. I run straight distilled water with WW. 30 minutes on track in 80F temps this past weekend and kept coolant temps below 220 according to HLT.
27364
 

Bnks334

Sergeant
Dec 1, 2016
275
New York
Edit: sorry i thought this was Asbjorn build thread lol I am referring to post #84 which shows the aluminum shrouding to all the coolers he has put into his car and is still struggling with temps. I just find it hard to believe doubling the radiator capacity did nothing. Either it's not getting air or it's not plumbed correctly and water isn't actually flowing through it.

I looked back through the thread and couldn't see much of your front bumper setup. Have you addressed AERO at all? You may actually have the cooling capacity you need you just might have to ensure air is flowing properly. There are an insane amount of minute details that go into a race-car and GT spec car that a lot of people don't notice. For example, the E92 M3 GT spec car BMW raced back in 2010-2011 used aerodynamically designed mirrors to draw hot exhaust out of the dump pipes and around the car...

You don't want air to be able to find ANY path around the oil cooler or radiator. If air can get AROUND the coolers it will NOT go through it. Path of least Resistance. All that bumper support that people hack out to fit large 7.5" intercoolers actually served a purpose. Look at OE fitment. Every little crevice is blocked off with either plastic or rubber strips. Same thing for the factory oil cooler... a duct funnels air to it from the bumper and then the slotted vent on the backside seals it to the fender liner. Look at the M4 GT spec cars front bumper in the above pics. Every single cooler is ducted and sealed to the bumper opening.

The vented hood is another excellent point. Every race car you see will have a vent right behind the radiator. A hood vent is in no way practical for any production car. Cooling is sacrificed by not having a hood vent to alleviate the pocket of high pressure air that forms from air hitting the front of the engine. Manufacturers compromise by trying to funnel the air underneath the car to keep the air moving around the engine. I think the factory intake design kind of exemplifies that. The scoops and ducting to the factory air box blocks off all the dead space above the radiator between the engine. The pocket of high pressure air it creates will serve to ensure that air flows down the face of the engine and under the car to exit...

Race cars go the opposite direction of this. They use body kits to seal the car to the ground (not lowering) and funnel all the hot air OVER the car and around it with hood vents and fender vents. This provide down-force, reduces lift, and massively increases airflow through the front fascia. Not so good for gas mileage or a daily driver but perfect for a race car.

Here is a quick link I found of some interesting bits about aero through a radiator. Event the radius of the bends in the ducting is important for ensuring you don't create vortices of air that restrict flow and do more harm than good: https://nasaspeed.news/tech/engine/rocket-science-achieving-better-engine-cooling-with-proper-aerodynamic-principles/

I think I've posted this here or maybe elsewhere but take a look at what Turner does with their M6... This car is amazing in person! A duct funnels the air from the back-side of the radiator right out the hood. The front fascia is completely sealed to the radiator. This car runs endurance races and doesn't need anywhere near the capacity or front fascia opening some of us have on our E82's. It looks so simple from the front bumper... almost factory street-car-like.
afe-power-air-filters-turner-motorsport-m6-gt3.jpg
 
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Asbjorn

Sergeant
Mar 10, 2018
292
Europe, based in China
Edit: sorry i thought this was Asbjorn build thread lol I am referring to post #84 which shows the aluminum shrouding to all the coolers he has put into his car and is still struggling with temps. I just find it hard to believe doubling the radiator capacity did nothing. Either it's not getting air or it's not plumbed correctly and water isn't actually flowing through it.

I looked back through the thread and couldn't see much of your front bumper setup. Have you addressed AERO at all? You may actually have the cooling capacity you need you just might have to ensure air is flowing properly. There are an insane amount of minute details that go into a race-car and GT spec car that a lot of people don't notice. For example, the E92 M3 GT spec car BMW raced back in 2010-2011 used aerodynamically designed mirrors to draw hot exhaust out of the dump pipes and around the car...

You don't want air to be able to find ANY path around the oil cooler or radiator. If air can get AROUND the coolers it will NOT go through it. Path of least Resistance. All that bumper support that people hack out to fit large 7.5" intercoolers actually served a purpose. Look at OE fitment. Every little crevice is blocked off with either plastic or rubber strips. Same thing for the factory oil cooler... a duct funnels air to it from the bumper and then the slotted vent on the backside seals it to the fender liner. Look at the M4 GT spec cars front bumper in the above pics. Every single cooler is ducted and sealed to the bumper opening.

The vented hood is another excellent point. Every race car you see will have a vent right behind the radiator. A hood vent is in no way practical for any production car. Cooling is sacrificed by not having a hood vent to alleviate the pocket of high pressure air that forms from air hitting the front of the engine. Manufacturers compromise by trying to funnel the air underneath the car to keep the air moving around the engine. I think the factory intake design kind of exemplifies that. The scoops and ducting to the factory air box blocks off all the dead space above the radiator between the engine. The pocket of high pressure air it creates will serve to ensure that air flows down the face of the engine and under the car to exit...

Race cars go the opposite direction of this. They use body kits to seal the car to the ground (not lowering) and funnel all the hot air OVER the car and around it with hood vents and fender vents. This provide down-force, reduces lift, and massively increases airflow through the front fascia. Not so good for gas mileage or a daily driver but perfect for a race car.

Here is a quick link I found of some interesting bits about aero through a radiator. Event the radius of the bends in the ducting is important for ensuring you don't create vortices of air that restrict flow and do more harm than good: https://nasaspeed.news/tech/engine/rocket-science-achieving-better-engine-cooling-with-proper-aerodynamic-principles/

I think I've posted this here or maybe elsewhere but take a look at what Turner does with their M6... This car is amazing in person! A duct funnels the air from the back-side of the radiator right out the hood. The front fascia is completely sealed to the radiator. This car runs endurance races and doesn't need anywhere near the capacity or front fascia opening some of us have on our E82's. It looks so simple from the front bumper... almost factory street-car-like.
afe-power-air-filters-turner-motorsport-m6-gt3.jpg
You make a very very good point.

When I replaced my FMIC with the custom HD version last week, the workshop started making a duct for my oil cooler because they heard I was planning to do the 1h endurance. In fact I hadn't even asked them to do this, they did this on their own initiative.

Based on your input (and OP has been saying the same) I am going back to have them repeat what they did for ALL coolers. As it is now, there are major air escape/leak routes below the FMIC and around the sides of the radiators due to all the custom work.

244133992.jpg
 
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Asbjorn

Sergeant
Mar 10, 2018
292
Europe, based in China
Watched a video about a guy solving a corvette overheating issue by heat-shielding one of the catalytic converters running close to the oil pan. It made me wonder if anyone has tried completely heat shielding against the coolant + oil lines and pan down there.

Was further inspired by below aftermarket turbo with built-in heat shielding. The M4 has something similar stock, and @Hydra Performance obviously thought about it as well.

If working on this benefits engine cooling (coolant, oil), it would perhaps also explain why some of the single turbo owners claim that they do not see overheating on track.

1709933159.jpg
 
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Hydra Performance

Sergeant
Free Vendor
Jan 31, 2017
258
@Asbjorn,
Here's an older pic of mine, wrapping the DPs probably isn't a bad idea either. On an unrelated note, I would imagine that my particular setup, which allows me to run a ridiculous (for an N54) amount of timing on pump gas, lowers EGTs and allows less heat rejection into the coolant.
ss2.PNG
 
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shushikiary

Corporal
Jun 4, 2018
118
Yes, and this is why you can get your down pipes and turbo's ceramic coated. Not only does it help with spool (heat flows out of the turbo, and thus through it) but it helps keep engine bay temps down as well.

So both my turbo's and my down pipes are ceramic coated.

Another thing that would help is to get more air flow through the area. For some reason there are those holes in the wheel well on the left side of the engine bay but not on the right side. It makes me wonder if that's to help push air through, down, and out the right side of the engine, rather than let it escape out through the wheel well like on the left side.

This then also makes me wonder if we would see any changes if we tried to help air move through the right side of the engine bay.... only one way to really find out I suppose.
 
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gmx

Private
Dec 8, 2017
39
Wrapped/coated DPs will reject heat and raise turbine temperatures, EGTs. Tap and put an EGT gauge, and you will see. If the car has a good head (N54 exhaust valve is tiny), using ethanol/methanol fuels, sure. FBO/standard "fragile" turbos, definitely would not recommend. Each to their own.

@Asbjorn You could try a simple plate placed between the oil pan and downpipes similar to the head.
 

Asbjorn

Sergeant
Mar 10, 2018
292
Europe, based in China
Wrapped/coated DPs will reject heat and raise turbine temperatures, EGTs. Tap and put an EGT gauge, and you will see. If the car has a good head (N54 exhaust valve is tiny), using ethanol/methanol fuels, sure. FBO/standard "fragile" turbos, definitely would not recommend. Each to their own.

@Asbjorn You could try a simple plate placed between the oil pan and downpipes similar to the head.
Yeah no reason not to try that at this point.

Meanwhile, here's some water temp and water pressure data from a Reb Bull honda powered formula 1 car yesterday. :grimacing:

IMG_20190609_121819.png
 

Asbjorn

Sergeant
Mar 10, 2018
292
Europe, based in China
Does anyone here know if the temperature differential across the radiator / engine can be read with BMW diagnostic software while driving? According to the N54 documentation, there should be a temperature sensor both at the engine outlet and at the radiator outlet.

If we could read both temperatures, it would allow us to determine if the coolant flow is adequate. If engine out is 230F while engine in is 158F, then turning up the flow alone should be enough to keep temps down. If engine out is 230F while engine in is 212F, then there's a radiator or air flow issue.

In my build thread, I have documented the build and test of a new setup consisting of CSF + three aux radiators w/ booster pump and improved ducting. While an improvement, I am still not satisfied with the performance (tested at 100-110F ambient). I need to figure out if the OEM electric pump is actually the bottle neck, despite theory saying it shouldn't be.

Everyone I have spoken to from the racing world, claim that I just have an air flow problem. They say air flow solves everything. The counter argument then being that air flow wasn't improved between the M2 and M2C, yet only one has an overheating issue. Yes I know the side ducts were enlarged, but...

1798126775.jpg
 

Jeffman

Captain
Jan 7, 2017
1,047
Watched a video about a guy solving a corvette overheating issue by heat-shielding one of the catalytic converters running close to the oil pan. It made me wonder if anyone has tried completely heat shielding against the coolant + oil lines and pan down there.

Was further inspired by below aftermarket turbo with built-in heat shielding. The M4 has something similar stock, and @Hydra Performance obviously thought about it as well.

If working on this benefits engine cooling (coolant, oil), it would perhaps also explain why some of the single turbo owners claim that they do not see overheating on track.

View attachment 27725
This makes so much sense - heat shielding the downpipes - this way even more heat goes out the tailpipe rather than radiate to the engine block.
 

Jeffman

Captain
Jan 7, 2017
1,047
Does anyone here know if the temperature differential across the radiator / engine can be read with BMW diagnostic software while driving? According to the N54 documentation, there should be a temperature sensor both at the engine outlet and at the radiator outlet.

If we could read both temperatures, it would allow us to determine if the coolant flow is adequate. If engine out is 230F while engine in is 158F, then turning up the flow alone should be enough to keep temps down. If engine out is 230F while engine in is 212F, then there's a radiator or air flow issue.

In my build thread, I have documented the build and test of a new setup consisting of CSF + three aux radiators w/ booster pump and improved ducting. While an improvement, I am still not satisfied with the performance (tested at 100-110F ambient). I need to figure out if the OEM electric pump is actually the bottle neck, despite theory saying it shouldn't be.

Everyone I have spoken to from the racing world, claim that I just have an air flow problem. They say air flow solves everything. The counter argument then being that air flow wasn't improved between the M2 and M2C, yet only one has an overheating issue. Yes I know the side ducts were enlarged, but...

View attachment 27895
I agree 100%. You really need good air flow through the radiators and coolers to maximize heat removal. Of the three ways to remove heat (radiation, conduction, and convection), convection by moving the cooler air over a hot surface is most effective way to cool.
 

RSL

Sergeant
Aug 11, 2017
347
Does anyone here know if the temperature differential across the radiator / engine can be read with BMW diagnostic software while driving? According to the N54 documentation, there should be a temperature sensor both at the engine outlet and at the radiator outlet.

If we could read both temperatures, it would allow us to determine if the coolant flow is adequate. If engine out is 230F while engine in is 158F, then turning up the flow alone should be enough to keep temps down. If engine out is 230F while engine in is 212F, then there's a radiator or air flow issue.

In my build thread, I have documented the build and test of a new setup consisting of CSF + three aux radiators w/ booster pump and improved ducting. While an improvement, I am still not satisfied with the performance (tested at 100-110F ambient). I need to figure out if the OEM electric pump is actually the bottle neck, despite theory saying it shouldn't be.

Everyone I have spoken to from the racing world, claim that I just have an air flow problem. They say air flow solves everything. The counter argument then being that air flow wasn't improved between the M2 and M2C, yet only one has an overheating issue. Yes I know the side ducts were enlarged, but...

View attachment 27895
I think early N5x had a rad outlet sensor, mine doesn't. For those without the outlet sensor, a substitute value of ECT (at the head) minus 7.5C is used for the TCO2 value, so logging the delta through the DME won't shed any light because it's constant. If you have the rad outlet sensor, can monitor in INPA, log with Testo and maybe others.

I think the top level difference there is open vs. closed deck, but surely a sum of a lot of factors. Definitely need flow out of the bay though or air can't flow in/through.
 
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