Yet another cooling (IC/HX) thread....kind of nerdy

[qcrazy]

Good info! My S6 airbox is still hooked up on my car. I'll try and get out there tomorrow and get a 'full test' completed this time. Test it and see if it will confirm what you are seeing.

[jsilas]

Subscribed - great thread, thank you for doing all this research! I'm doing a Stage 3 build on a C7.5 S6 right now and cooling will be a challenge - I'm planning to let your findings in this thread guide me!

[qcrazy]

Still not seeing much with the S6 airbox (dashed yellow line). This is the only run with the S6 airbox (hence the dashes), the rest are all using the full SRM inlets. My foot got a little heavy, but the trends still follow...
HeatSoakWarmup2.JPG
Since it jumps at each boost iteration, that points to the fact that the issue is caused by the "turbo oven". The airbox being solely fed by outside air does not appear to be making a difference on dealing with the oven as it warms up.

Here is the run after it was heatsoaked. This run is real similar to the other (SRM Inlet) iterations.
HeatSoakCooldown2.JPG
On the far end of the run the S6 airbox is a bit lower than the other runs. While it is a small difference, it just may be enough to indicate a difference from the SRM inlets. I am not about to run a regression analysis on this, if it is a statistical difference, it is a marginal gain at best. While we are running about 35F higher than we want to at this point, the S6 airbox may actually provide a few degrees in the right direction....but just a few degrees, maybe 5F.

I do find it interesting that the S6 airbox is similar to the grey "removed scoop" run with the SRM inlets. This is when I removed the gooseneck scoop that connects to where the airbox would be when I was running the SRM inlets. The theory was that the air would blow directly on the "turbo oven" and help cool it down. Paradoxically, with the scoop removed very little fresh air would have blown on the actual SRM filters. It is curious that the S6 airbox that is only sucking fresh air, is similar to the "removed scoop" run that would have seen very little fresh air. That makes me think the difference with the S6 airbox is likely not statistically significant...but I don't know for sure. I do know it's not enough for me to mess with at this point.

[IHave2Turbos]

since i don't have a logging setup i will ask again. could you get numbers with the rear piece of engine weather stripping removed to see if/how temps are effected?

question for DS1, can you programmatically open the thermostat earlier to in theory run the engine cooler?

could you programmatically run the puller fans sooner/faster ?

[qcrazy]

I'll pull the weather stripping and test it one of the days this week. I played with this on a B5 years ago and it didn't do anything, but we'll check this too.

I would think the temp could be adjusted. The N489, switching valve, is fully electronic. There is also a typical wax thermostat (97C) in these cars, but Audi has a heating element with them so they can adjust when they open per the ECU. That said, lowering these temps won't do much for intake cooling. It is not directly the heat of the coolant that is the issue, but the heat of combustion. The EM's are much hotter then the coolant, and varying the coolant a few degrees will not effect the temperature of the EM.

DS1 has a max cooling map already. But they state it is based on a stock-like map.

[Dasquade]

Still not seeing much with the S6 airbox (dashed yellow line). This is the only run with the S6 airbox (hence the dashes), the rest are all using the full SRM inlets. My foot got a little heavy, but the trends still follow...
HeatSoakWarmup2.JPG
Since it jumps at each boost iteration, that points to the fact that the issue is caused by the "turbo oven". The airbox being solely fed by outside air does not appear to be making a difference on dealing with the oven as it warms up.

Here is the run after it was heatsoaked. This run is real similar to the other (SRM Inlet) iterations.
HeatSoakCooldown2.JPG
On the far end of the run the S6 airbox is a bit lower than the other runs. While it is a small difference, it just may be enough to indicate a difference from the SRM inlets. I am not about to run a regression analysis on this, if it is a statistical difference, it is a marginal gain at best. While we are running about 35F higher than we want to at this point, the S6 airbox may actually provide a few degrees in the right direction....but just a few degrees, maybe 5F.

I do find it interesting that the S6 airbox is similar to the grey "removed scoop" run with the SRM inlets. This is when I removed the gooseneck scoop that connects to where the airbox would be when I was running the SRM inlets. The theory was that the air would blow directly on the "turbo oven" and help cool it down. Paradoxically, with the scoop removed very little fresh air would have blown on the actual SRM filters. It is curious that the S6 airbox that is only sucking fresh air, is similar to the "removed scoop" run that would have seen very little fresh air. That makes me think the difference with the S6 airbox is likely not statistically significant...but I don't know for sure. I do know it's not enough for me to mess with at this point.

Thanks for testing ;) now we know at least. And yes, i also belief the main issue is in the "turbo oven" where whatever 'cold air' quickly heats up by the time it hits the throttle body IAT before charge cooler sensors. I only wanted to share and point out my in airbox temp sensor witch is/was for most a big unknown. Would have been nice if you were able to messure those in your test aswell, especially with the open srm filter setup (maybe as your data shows it doesn't mather that much...well at least under airflow/speed).

[Optimus247]

Time to put a shaker hood on or cut a vent in the hood ...??

[sepheroth86]

Time to put a shaker hood on or cut a vent in the hood ...??

While I think an "EVO" style vent would look terrible. I would be willing to wager it would help keep temps down a bit.

From all of the road course cars that I have seen, holes in the hood need to be no further back than the middle of the fender/hood from the front of the vehicle in order to be effective.

[qcrazy]

Time to put a shaker hood on or cut a vent in the hood ...??

Vented hood is unlikely to help. I've been down that road before. Even went with an extraction hood. Ended up having to go a completely different route to solve the issue on that car...

YelS4-Hood.jpg
P6050247.jpg

[qcrazy]

Put the SRM Inlets back in. Pulled the rear engine hood seal. Also, pulled the plenum cover, since the seal held it in. Looking it over, I thought it made sense to pull the engine cover too...since we are trying to blow the heat out. No difference.
HeatSoakWarmupNoSeal.JPG
As you can see it makes no difference on temps at all. Although, if you think SRM Inlets are loud try driving the car with the seal and plenum cover removed. Holy crap! Sounds like it is piped into the speakers!!

Out of curiosity, I also checked coolant temps during the run, to see if pulling the seal affected air flow through the engine. It doesn't appear to do so enough to change the coolant temps....
CoolantTemps.JPG

[IHave2Turbos]

wow its nuts that nothing seems to impact temps good or bad. thank you for doing all this work

[sepheroth86]

No hood time!🤣🤣🤣

[Optimus247]

Vented hood is unlikely to help. I've been down that road before. Even went with an extraction hood. Ended up having to go a completely different route to solve the issue on that car...

YelS4-Hood.jpg
P6050247.jpg

Not to completely start another discussion ... but, for the V8TT ... maybe a vent closer to the windshield ... since that is where the exhaust is ...??

But, since you did all that other trim removal ... probably answered that question ... just a thought ...

Aero dynamics around the hood would require some taped on yarn to understand the wind flow across the hood and windshield ... since the bottom of the car is a plane surface ...

A track car would be easy to fix ... just cut a hole and add a scoop ...

[Dasquade]

Not to completely start another discussion ... but, for the V8TT ... maybe a vent closer to the windshield ... since that is where the exhaust is ...??

But, since you did all that other trim removal ... probably answered that question ... just a thought ...

Aero dynamics around the hood would require some taped on yarn to understand the wind flow across the hood and windshield ... since the bottom of the car is a plane surface ...

A track car would be easy to fix ... just cut a hole and add a scoop ...

For what it is worth, my logging more and more show it is simply internal material heatsoak. My iats (after cooling) is almost identical as the heat buildup in the turbo valley and it raises and goes static in same line with those temps i read there.
Something tells me up top we have a pretty static pressure and not much flow (since the intake manifold blocking most incomming air). I still plan to mount two hoodvents and so far it looks i will mount them above where the hpfp are...if standing still and fans full blast, that is where all radiator heat first hit upwards.
Again, i think it is only an other heatsoak delay thingy :).
For the rest i will relay on wmi to do the rest and internal cooling...

[sepheroth86]

For what it is worth, my logging more and more show it is simply internal material heatsoak. My iats (after cooling) is almost identical as the heat buildup in the turbo valley and it raises and goes static in same line with those temps i read there.
Something tells me up top we have a pretty static pressure and not much flow (since the intake manifold blocking most incomming air). I still plan to mount two hoodvents and so far it looks i will mount them above where the hpfp are...if standing still and fans full blast, that is where all radiator heat first hit upwards.
Again, i think it is only an other heatsoak delay thingy :).
For the rest i will relay on wmi to do the rest and internal cooling...

For hood vents to be most effective. One has to create a low pressure zone for the air to escape. On Miata's and many other track cars, they use a flat blade in front of the vent to create a low pressure pocket. See pic below.

[Dasquade]

And again sorry for adding, but since i have temp sensors before and after HX (not sure where qcrazy gets his coolant temp data from since we stock dont have exclusive charge cooler temps)....anyway IF my setup works and if my coolant temps are correct, it shows it works good. My charge cooling coolant loop (since non divorced) shows up equal to ambiant temp on cold. Super slowly goes +5/max10°C while driving and never goes higher then +15/20°C with a pretty quick recovery time back to +5°C ambiant (current 22-25°C ambient here). Granted i didnt do much full boost/long/multiple pulls as i'm still midway my ts1 upgrade build....but looks the base is there, decent enough flow on par with coolant volume/cooling surface. So dual cwa100 with decent sized HX definatly works for daily TS1 setup.

[qcrazy]

And again sorry for adding, but since i have temp sensors before and after HX (not sure where qcrazy gets his coolant temp data from since we stock dont have exclusive charge cooler temps)....anyway IF my setup works and if my coolant temps are correct, it shows it works good. My charge cooling coolant loop (since non divorced) shows up equal to ambiant temp on cold. Super slowly goes +5/max10°C while driving and never goes higher then +15/20°C with a pretty quick recovery time back to +5°C ambiant (current 22-25°C ambient here). Granted i didnt do much full boost/long/multiple pulls as i'm still midway my ts1 upgrade build....but looks the base is there, decent enough flow on par with coolant volume/cooling surface. So dual cwa100 with decent sized HX definatly works for daily TS1 setup.

The coolant temps I posted above where from the engine, I was just confirming the engine temps were staying in the normal range with the different set-ups...and they were.

There is not a big reason to check the coolant temps on the IC. IC coolant temps will mimic the air temps. You want your coolant temps MUCH closer to ambient, what you have is not ideal. For every one degree of coolant temperature you gain, you will be giving up ~four degrees of air temperature. Your coolant temps actually confirm the heat soak issue that we have already identified.

You are saying they are usually around 5/10C above ambient max...lets just say 5C above ambient. 5C above ambient in your coolant would be about 20C above ambient in the air (5 x 4). 20C is 36F (20 x 1.8). So this is telling us that your intake air is running about 36F above ambient. That sure looks close to...
HeatSoakWarmup2.JPG

Your coolant temps are indicating exactly why we've gone on this little tangent on air intake temps. High intake temps, heat up your coolant. Warm coolant limits the systems effectiveness. We want our air intake temps as close to zero as we can get them, because that will push our coolant temperatures close to zero. And that will make this all work better when we go under boost.

[kaploww]

Put the car on a dyno.

Disconnect and loop the coolant lines to the intercooler together with an adapter.

Connect a garden hose to the intercooler coolant inlet that connects directly to 40 psi of municipal water.

Connect a garden hose to the intercooler outlet that runs to a drain.

You will still have IAT problems at the end of a fourth gear pull if you are making around APR stage 2 power or better.

The problem is the charge cooler brick surface area is too small.

It doesn’t matter how cold you get the water going into the charge cooler, once the charge cooler is boiling the coolant, it’s boiling the coolant.

There’s nothing you can do about it.

Keep in mind I ran this test on a dyno utilizing cold water coming out of the ground that was dumped into the gutter after it left the intercooler.

I probably went through thousands of gallons of water.

The charge cooler brick is the problem.

Period.

[mpk1996]

Put the car on a dyno.

Disconnect and loop the coolant lines to the intercooler together with an adapter.

Connect a garden hose to the intercooler coolant inlet that connects directly to 40 psi of municipal water.

Connect a garden hose to the intercooler outlet that runs to a drain.

You will still have IAT problems at the end of a fourth gear pull if you are making around APR stage 2 power or better.

The problem is the charge cooler brick surface area is too small.

It doesn’t matter how cold you get the water going into the charge cooler, once the charge cooler is boiling the coolant, it’s boiling the coolant.

There’s nothing you can do about it.

Keep in mind I ran this test on a dyno utilizing cold water coming out of the ground that was dumped into the gutter after it left the intercooler.

I probably went through thousands of gallons of water.

The charge cooler brick is the problem.

Period.

does the merc unit help this at all?

[kaploww]

Maybe.

Once the charge cooler brick reaches its thermal capacity.

It’s done.

If your bank 1 and/or bank 2 IAT’s are at 170-190C for any length of time.

The best the post intercooler IAT’s are gonna be is 70-90C.

It removes about 100C worth of temp, but it’s done after that.

Your post Intercooler IAT’s will be north of 70C which initiate timing pull on any sane tune that’s not focused on wringing ever last bit of power out of the system at the expense of IAT’s and detonation/timing pull.

[Optimus247]

I checked the codes ... I might have an engine mount issue ... will investigate this weekend ...

But, I long coded the 'Lap Timer' and now I am Oil Temperature aware ... the boost gauge is a little useless, as it only shows a scale of how much ... no numerical value ... and not in the HUD ...

So, with the Oil temperature ... it only takes a few heavy pedals to make the oil temp soar ... it cools off well enough, but makes me want an additional oil cooler ...

I know the oil temp and water temp follow one another ... maybe add a mini remote oil cooler to help the water lose some thermal energy ...?

I see that my morning drive temps are 10 degrees cooler than the afternoon drive temps ...

[Audisom]

So what have we learned? Kaploww shared his research reguarding the limitations of the factory brick. Is there a worthwhile modification to be done or is air to air the only solution above stage 1? Sorry if this is obvious but the data which qcrazy collected is hard for met to understand

[ericw.]

So what have we learned? Kaploww shared his research reguarding the limitations of the factory brick. Is there a worthwhile modification to be done or is air to air the only solution above stage 1? Sorry if this is obvious but the data which qcrazy collected is hard for met to understand

Captain Contradiction? Yeah last time he was on here talking about cooling, he had the answer to 300% cooling efficiency gains and the data to prove it but was 'too valuable' to show anyone his work. lol I'm not religious for the same reason I wouldn't believe that excuse... everything he says should be ignored, his advice and opinion entirely depends on who he's talking to or what side of the fence he's on at the moment. (ie what's he selling right now? what's his motive to stop the research & development?) There's your disclaimer.

OP should continue his research and disregard anything else.

[ry0t05]

Nooooo don't do this shit to this thread

[ericw.]

Nooooo don't do this shit to this thread

glad I'm not the only one who remembers...



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[sepheroth86]

I would like to see a run (data) using the method Kaploww suggested. (Pumping fresh cold water from the tap through the system as quickly as the garden hose would allow) Would be an interesting experiment to test the maximum cooling capacity of the chiller brick.

That being said, I do hope that OP does continue with his investigation and comes up with something beneficial.

[ericw.]

I would like to see a run (data) using the method Kaploww suggested. (Pumping fresh cold water from the tap through the system as quickly as the garden hose would allow) Would be an interesting experiment to test the maximum cooling capacity of the chiller brick.

That being said, I do hope that OP does continue with his investigation and comes up with something beneficial.

Distilled water only when you're mixing concentrated coolant. Tap water has calcium and magnesium (among others) that deposit in the system and degrades performance. Minerals in the cooling system can cause a lot of other issues also including rust.

[sepheroth86]

Distilled water only when you're mixing concentrated coolant. Tap water has calcium and magnesium (among others) that deposit in the system and degrades performance. Minerals in the cooling system can cause a lot of other issues also including rust.

I wouldn't think that for a handful of dyno pulls (20-30 minutes of use) it would create any significant long term issues.

[Alabama]

Distilled water only when you're mixing concentrated coolant. Tap water has calcium and magnesium (among others) that deposit in the system and degrades performance. Minerals in the cooling system can cause a lot of other issues also including rust.

I wouldn't think that for a handful of dyno pulls (20-30 minutes of use) it would create any significant long term issues.

As far as I know, you're both right! Calcium causes "scale" build up, but over time and more when there is no flow. Calcium concentrations will vary among tap waters, but distilled should pretty much always be much less (but not necessarily zero) so would be preferable for long term use. I imagine after the brief experiment one could flush the system to remove the vast majority of the water from the garden hose. Maybe some member has an industrial water chiller that could circulate ericw.'s proper coolant mix, or is willing to donate their radiator to Science!

[AudiC7Owners]

As far as I know, you're both right! Calcium causes "scale" build up, but over time and more when there is no flow. Calcium concentrations will vary among tap waters, but distilled should pretty much always be much less (but not necessarily zero) so would be preferable for long term use. I imagine after the brief experiment one could flush the system to remove the vast majority of the water from the garden hose. Maybe some member has an industrial water chiller that could circulate ericw.'s proper coolant mix, or is willing to donate their radiator to Science!

Additionally, the coolant hardlines that run down the front of your engines are already restrictive. Replacing them with 3/4" coolant housing will increase flow a good bit

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[qcrazy]

Additionally, the coolant hardlines that run down the front of your engines are already restrictive. Replacing them with 3/4" coolant housing will increase flow a good bit

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No they won't. My flow testing clearly showed where the system restriction is. And it is not in the hoses/lines.

[AudiC7Owners]

No they won't. My flow testing clearly showed where the system restriction is. And it is not in the hoses/lines.

So having larger diameter hosing won't aid in recovery?

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[qcrazy]

It's not that it wouldn't aid in recovery, but it would be a bad place to put any effort. You could likely aid your recovery more by just pulling your bumper and cleaning the dead bugs out of your heat exchanger.

Below is all the system curves...on a stock S6/S7. The white line is the entire system; the other lines below that are the individual components that make up the full system. The solid blue line is the "hose" system curve.
AllSystems.JPG
For those that don't remember, the steeper the system curve, the worse it is. A theoretical "perfect" system curve would be a horizontal line (this does not exist IRL). You can see the blue line is pretty flat already, and this includes all the hoses, the hardlines, and all the bends. Typically the bends in piping create most of the restriction, and I am sure this is no different. There is just not much to gain in this portion of the system.

On a stock system with a stock pump we flow 3.6 gpm. On a stock system with an EMP we will flow 6.4 gpm. Most people on this forum are likely to fall somewhere between those two flows. At 4 GPM all the "hoses" create 1.5 psi of restriction. If we say that half of that restriction is the hardline, that means you can only affect 0.75 psi worth of restriction at 4 gpm. Just not much there to chase. But the stock hx at 4 gpm has ~8psi of restriction, there we have something to work with.

If we were running really high flows, like double digit flows it may start to make more sense. But where most people on here run, it is not the best place to start. My last post was done at 6.7 gpm. I plan to go out tomorrow and check two pumps and I should be at 7.9 gpm. After that I install the EMP in my set-up and should then be 10+ gpm from that point on. Even at 10+ gpm I would bet the gains will still be minor. We'll see what happens soon enough I guess.

[AudiC7Owners]

It's not that it wouldn't aid in recovery, but it would be a bad place to put any effort. You could likely aid your recovery more by just pulling your bumper and cleaning the dead bugs out of your heat exchanger.

Below is all the system curves...on a stock S6/S7. The white line is the entire system; the other lines below that are the individual components that make up the full system. The solid blue line is the "hose" system curve.
AllSystems.JPG
For those that don't remember, the steeper the system curve, the worse it is. A theoretical "perfect" system curve would be a horizontal line (this does not exist IRL). You can see the blue line is pretty flat already, and this includes all the hoses, the hardlines, and all the bends. Typically the bends in piping create most of the restriction, and I am sure this is no different. There is just not much to gain in this portion of the system.

On a stock system with a stock pump we flow 3.6 gpm. On a stock system with an EMP we will flow 6.4 gpm. Most people on this forum are likely to fall somewhere between those two flows. At 4 GPM all the "hoses" create 1.5 psi of restriction. If we say that half of that restriction is the hardline, that means you can only affect 0.75 psi worth of restriction at 4 gpm. Just not much there to chase. But the stock hx at 4 gpm has ~8psi of restriction, there we have something to work with.

If we were running really high flows, like double digit flows it may start to make more sense. But where most people on here run, it is not the best place to start. My last post was done at 6.7 gpm. I plan to go out tomorrow and check two pumps and I should be at 7.9 gpm. After that I install the EMP in my set-up and should then be 10+ gpm from that point on. Even at 10+ gpm I would bet the gains will still be minor. We'll see what happens soon enough I guess.

Thanks for the explanation. I actually forgot your tests were on a 4.0t.

I was taking about the 3.0t coolant lines, which are much easier to swap out (super simple job when divorcing the system).

You need to get someone with a 3.0t to volunteer their car to you for the same kind of testing

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[hunter_killer]

I’m gonna ask here and I haven’t personally had enough time to look at a 4.0 under the hood, but is it worth while deleting the intercooler bricks entirely and changing the intake system to a W2A or A2A setup and just have the intake manifolds empty? Or making new intakes that are accommodating for larger intercoolers?
Is there space for a large external cooler or two smaller ones in the bumpers not possible?

Plenty of turbo builds run without having a intercooler in the manifold so unless it’s absolutely needed in this platform is my thinking wrong?


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[IHave2Turbos]

it has been explored, i think the one A2A setup that is available is like $6000

Edit: https://dmt-racing.net/en/catalog/ai...r-cooling-kit/

[Alabama]

You could likely aid your recovery more by just pulling your bumper and cleaning the dead bugs out of your heat exchanger.

Really good reminder! It's the simple things . . . . .

[135Hoser]

it has been explored, i think the one A2A setup that is available is like $6000

Edit: https://dmt-racing.net/en/catalog/ai...r-cooling-kit/

SRM is making one as well. Should be coming to market "soon"

[kaploww]

I wouldn't think that for a handful of dyno pulls (20-30 minutes of use) it would create any significant long term issues.

Correct.

It’s a nothing burger.

You’re also not going to get any rust from this test.

Kinda hard to get rust when the entirety of the coolant system and components are brass, rubber, aluminum cylinder heads, aluminum radiators, aluminum hard pipes, and a high silicon content hypereutectic aluminum sleeveless engine block. There’s nothing to rust in the system.

Then when connecting the intercooler back to the factory lines, I flush with OEM spec coolant for a few seconds and call it a day.

Zero adverse affects on the system.

It was a pretty cool test, that was conducted over the course of two days while tuning this car.

https://www.audiboost.com/content.ph...duces-666-awhp

The most interesting thing of note was the recovery time required between pulls.

Keep in mind the system itself at this point is just a hose from the water municipality, and the intercooler brick.

There’s no heat exchanger.

Just cold water dumping into the intercooler, then dumping out the outlet, and into a drain.

Even with the hose running wide open, the IAT’s at let off would hover around 60-70C which still pretty high, and took about 5 min to recover to the flowing water temp which was around 30C before we could conduct another pull.

One thing.

***I am no longer with SRT/SRM, and have not been for over a year. I am also no longer working in the tuning industry in any way shape or form.***

I’m just another enthusiast for the platform at this point trying to pass on some info from my lessons learned calibrating the ECU, TCU, and hardware development.

[qcrazy]

So did they just use cold water in the intercooler to hit their high marketing hp number?

I would be curious what your fan arrangement and output was when you did the testing. 60C is not great, but doesn't sound all that bad depending on the temperature of the shop and your air flow through/over the engine. If it was heat soaked bad (high pre IC temps), the temps would not have to climb all that much to see 60C. On the road, 30C for recovery is about impossible with this system... except for maybe in deep winter.

I still need to get my findings posted on heat soak. A few interesting findings in that area.