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Car overheating on track days...(Use distilled water or WaterWetter?)

Lao278

Passed Driver's Ed
I used to run into overheating issues before then I bought a spare hood and cut some hood vents and my coolant temps peaked at 235° but never overheated/lost power this past weekend at Gingerman raceway, 75° sunny day. I was pushing my car pretty hard too since I just upgraded my pads/rotors and got RE71R tires.
 

PandaGTI

Go Kart Champion
These are all great ideas.

In addition to this you can also
- run the stock tune in the AM sessions then as you get more comfortable and faster then do a session later in the AM on the 91 oct Ko4 tune (or 93 if your not in california) to get your fastest times then take it easy when the engine temps start to go up.
- during your actual "time attack" session maybe even use 100 oct combined with the 91 setting on the Ko4 tune or use a water meth setup to liquid cool then engine
- run an E85 tune
 

Lao278

Passed Driver's Ed
These are all great ideas.

In addition to this you can also
- run the stock tune in the AM sessions then as you get more comfortable and faster then do a session later in the AM on the 91 oct Ko4 tune (or 93 if your not in california) to get your fastest times then take it easy when the engine temps start to go up.
- during your actual "time attack" session maybe even use 100 oct combined with the 91 setting on the Ko4 tune or use a water meth setup to liquid cool then engine
- run an E85 tune


Water/meth injection doesn't help with the overall coolant/oil temps. Myself and another user have w/m and we both were overheating at the track.
 

jay745

What Would Glenn Danzig Do
Water/meth injection doesn't help with the overall coolant/oil temps. Myself and another user have w/m and we both were overheating at the track.

It most likely is helping with oil temps. Unless you have an oil gauge tapped at the oil pan you can't really say that it is or isn't helping. It doesn't appear to be helping with coolant temps by much though I will say that.
 

Lao278

Passed Driver's Ed
It most likely is helping with oil temps. Unless you have an oil gauge tapped at the oil pan you can't really say that it is or isn't helping. It doesn't appear to be helping with coolant temps by much though I will say that.

I doubt w/m helps with your oil temps that much or we wouldn't be overheating since oil temps and coolant temps are related with the OEM oil cooler in place.
 

D-saint077

New member
Hello OP, I changed all my liquids with Motul Sport. (Trans, oil, breaks and coolant) For coolant i use Mo-cool with water and it works fine, no over heating. Huge difference from the first time i went to the track. Some of my friends run with an oil cooler and never have any overheating problems.
 

PandaGTI

Go Kart Champion
Water/meth injection doesn't help with the overall coolant/oil temps. Myself and another user have w/m and we both were overheating at the track.

W/M + taking out the weather strip + running the heater + aux oil cooler + engine tune set to 91 oct + manually shifting the DSG rather than letting S mode shift would get me a few extra laps before having to let the car cool.

In moderately aggressive driving according to my oil temp probe it kept the oil temps maybe 10 to 15 degrees cooler... but once you go to 10/10's for your fast lap none of the above really mattered much.

I also had one of the few Arkym vented CF hoods that helped a little but at speed it would flex enough that you need the hood pins to make sure it doesn't fly open.

Still after all of that the car would still overheat and eventually led to another warped headgasket...

After getting rid of that car and transferring the major mods onto my wife's VW CC I am not having any overheat issues and this is without the aux oil cooler. I think the difference is that my GTI had a really aggressive tune meant more for drag racing than track use... my wife's CC has an APR tune and it's been fine on the handful of track days I've done with it.

I think another factor is that past 300crank hp the Ko4 is working outside of its efficiency range. That little turbo has to spin much faster to make boost than a larger turbo. The Ko4 on my GTI was running so hot that it melted the welds around the flange that connects the downpipe to the turbo and popped it clean off at the welds. I think a larger turbo would run cooler and within its efficiency range.

Another thing that may help is running an electric push fan in front of the radiator... On the higher speed tracks like Big Willow the engine temps would come down pretty significantly on the front straight running flat out... I'm thinking a push fan could mimic that kind of airflow.

Lastly a high performance radiator would help alot as well. When I had my GTI there wasn't any made at the time. I tried a Mishimoto radiator however I think it only fit the FSI engine unless the ends of it where modified.

So to sum it up... push fans to force more cool air into the radiator + run the heater to pull the hot air out + remove the weather strip to allow the hot air to vent out + fabricate a high performance radiator + run a mild tune or set to a stock tune with stock boost levels + big turbo + oil cooler
 

Lao278

Passed Driver's Ed
W/M + taking out the weather strip + running the heater + aux oil cooler + engine tune set to 91 oct + manually shifting the DSG rather than letting S mode shift would get me a few extra laps before having to let the car cool.

In moderately aggressive driving according to my oil temp probe it kept the oil temps maybe 10 to 15 degrees cooler... but once you go to 10/10's for your fast lap none of the above really mattered much.

I also had one of the few Arkym vented CF hoods that helped a little but at speed it would flex enough that you need the hood pins to make sure it doesn't fly open.

Still after all of that the car would still overheat and eventually led to another warped headgasket...

After getting rid of that car and transferring the major mods onto my wife's VW CC I am not having any overheat issues and this is without the aux oil cooler. I think the difference is that my GTI had a really aggressive tune meant more for drag racing than track use... my wife's CC has an APR tune and it's been fine on the handful of track days I've done with it.

I think another factor is that past 300crank hp the Ko4 is working outside of its efficiency range. That little turbo has to spin much faster to make boost than a larger turbo. The Ko4 on my GTI was running so hot that it melted the welds around the flange that connects the downpipe to the turbo and popped it clean off at the welds. I think a larger turbo would run cooler and within its efficiency range.

Another thing that may help is running an electric push fan in front of the radiator... On the higher speed tracks like Big Willow the engine temps would come down pretty significantly on the front straight running flat out... I'm thinking a push fan could mimic that kind of airflow.

Lastly a high performance radiator would help alot as well. When I had my GTI there wasn't any made at the time. I tried a Mishimoto radiator however I think it only fit the FSI engine unless the ends of it where modified.

So to sum it up... push fans to force more cool air into the radiator + run the heater to pull the hot air out + remove the weather strip to allow the hot air to vent out + fabricate a high performance radiator + run a mild tune or set to a stock tune with stock boost levels + big turbo + oil cooler

I do agree with you on the K04 being pushed way beyond it's efficiency once you get passed a 300HP, oil cooler, and having the heat on. I'm running a stage 2+ Golf R and I was overheating at the track until I bought a spare hood and cut vents into and my coolant temp never passed 235° on a 75° sunny day. Where as before on the same track, I was overheating on a mid 60°s cloudy day.


 

ebuuz

Go Kart Newbie
I wonder if it would benefit to take off the hood completely and track without one.. I guess you'd lose some aerodynamics and protection of engine bay components if anything were to happen
 

jay745

What Would Glenn Danzig Do
I wonder if it would benefit to take off the hood completely and track without one.. I guess you'd lose some aerodynamics and protection of engine bay components if anything were to happen

I would definitely not do that. There's a ton of stuff that is on the track that your hood takes a hit on. The aero would be completely messed up as well like you said.
 

MrFancypants

Autocross Champion
Has anybody spent any time measuring the air pressure at various points around the car while it's in motion using something like a Magnehelic gauge? If you're feeling fancy you can probably rig up a bunch of barometers and log it with a laptop.

To oversimplify the complex and unpredictable subject of fluid dynamics, air flows from higher pressure areas to lower pressure areas. Consider your tires, they're inflated to a relatively high pressure. When you open the valve air flows out into the atmosphere, the only way to add air is to connect a source of air that's pressurized to a higher level, such as a tank containing air compressed at a higher rate than the tire.

This is the best picture I could find....



The red spots are high pressure areas. Our cars are obviously not those, but they'll share two things, the high pressure area at the front bumper and at the base of the windshield (cowl).

So if I were having cooling issues, I would want answers to these questions...

1. what is the pressure differential between the various points in front of the grill (upper and lower) where air is meant to enter the engine bay, and the various points between the radiator and the drivetrain

2. what is the pressure differential between the back of the engine bay at the firewall and the base of the cowl, with the rubber strip on and off the car.

3. what is the relationship between those two points, as in... if the weather strip is removed does the pressure differential between the primary cooling hardware at the front of the car become less favorable

Regarding #2, I feel that is it a near certainty that the air pressure at the base of the windshield is higher than the pressure at the back of the engine bay. That means that air would be entering the engine bay at the base of the windshield instead of leaving it (this is why the vents for the interior are in that spot). This might be beneficial, maybe removing the strip increases airflow through the back of the engine bay and out of the bottom of the car, helping push the hot air around the turbo out.


But, what #3 would answer is..... that it might be counter productive. Raising the air pressure at the back of the engine bay might be having a negative effect at the front where your main heat exchangers are mounted.

The hooded vent on Lao278's car absolutely makes sense. He's created a low pressure escape for the air that entered through the grill of the car. He's created more airflow through his cooling stack and it worked.

A thought regarding the placement of the aftermarket oil cooler.... is right in front of the condenser really the best spot? Some MkVs could be had with auxiliary radiators located behind the bumper cover on the driver's side (US)...


http://www.golfmkv.com/forums/showthread.php?t=117682&page=5

There's surely plenty of room to fit an oil cooler in there. Remove the fog lights, put holes in the plastic trim, add this behind it...



Your radiator would probably be a lot more effective if you weren't sending air into it that had already passed through an oil cooler with 240+ degree fluid running through it.

Then there's this...



Yeah that's the R32 belly pan, but the stock one has NACA ducts in those same spots. If you go with a high quality, durable plate and fin oil cooler that seems like a safe place to try to mount the oil cooler as well.
 
Last edited:

red_stapler

Ready to race!
But, what #3 would answer is..... that it might be counter productive. Raising the air pressure at the back of the engine bay might be having a negative effect at the front where your main heat exchangers are mounted.

Thanks, that was much more eloquent than my attempts at explaining earlier in the thread.
 

MrFancypants

Autocross Champion
Thanks, that was much more eloquent than my attempts at explaining earlier in the thread.

Yeah, and moving hot air away from the turbo is something, but the turbo probably isn't the best heat exchanger. So I think a better approach is to focus on airflow through the actual heat exchangers.

That said I'm not going to claim to know that to be an absolute fact without taking collecting some data, but most information you can find out there regarding how air flows around a car in motion suggests that you want that portion of the hood to remain sealed unless you have a very specific reason to open it (like a cowl induction intake).

I also have to wonder what removing that strip is doing for your interior vents. If you're trying to use the heater core to shed a bit more heat removing the strip might be robbing you of fresh air to do that with.

I guess another way to test this is before and after logs of the coolant and oil temps. Assuming a four run day trying to get the two in the mid day window to minimize ambient temperature deviation would be interesting to see.

So what aspect of a tune is causing the heat? Is it simply higher turbine speeds creating more heat being passed to the oil and coolant? Higher IATs? More fuel burned in the combustion chamber? All of the above?
 

Cadubya

Autocross Newbie
Yeah, and moving hot air away from the turbo is something, but the turbo probably isn't the best heat exchanger. So I think a better approach is to focus on airflow through the actual heat exchangers.



That said I'm not going to claim to know that to be an absolute fact without taking collecting some data, but most information you can find out there regarding how air flows around a car in motion suggests that you want that portion of the hood to remain sealed unless you have a very specific reason to open it (like a cowl induction intake).



I also have to wonder what removing that strip is doing for your interior vents. If you're trying to use the heater core to shed a bit more heat removing the strip might be robbing you of fresh air to do that with.



I guess another way to test this is before and after logs of the coolant and oil temps. Assuming a four run day trying to get the two in the mid day window to minimize ambient temperature deviation would be interesting to see.



So what aspect of a tune is causing the heat? Is it simply higher turbine speeds creating more heat being passed to the oil and coolant? Higher IATs? More fuel burned in the combustion chamber? All of the above?



For the K04 it's a turbo operating way out of its efficiency range. High boost + low efficiency = lots of heat.
 

MrFancypants

Autocross Champion
For the K04 it's a turbo operating way out of its efficiency range. High boost + low efficiency = lots of heat.

So basically, ask your tuner to tune for peak efficiency according to the compressor map?


Regarding the weather strip, it looks like Modshack performed some tests...

http://www.golfmk6.com/forums/showthread.php?t=39763

He sums it up by saying that it will reduce engine bay temps, bit not necessarily engine temps. So this doesn't look helpful, but maybe not harmful either.
 
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