S4 B8/B8.5 Heat Exchangers Overview

[Mat@1975]

Hello Guys,

I noticed that there were sometimes divergent opinions or misunderstantings about the several heat exchangers that are on our S4's

So: i took the initiative of staring a dedicated thread about the numerous Heat Exchangers and their functions

First, here is a schematic overview of all possible HX's ont our S4's:





1. Engine Water Cooler. Nothing special to say i would said.

2. A/C fluid heat exchanger. Same observation.

3. Supercharger water heat exchanger. It's a cooler for the S/C loop. It cools the water taht have been heated in the 2 HX on each side of the supercharger. The goal is to lower IAT.

4. Auxilliary Water cooler. Not clear on what version it is present, but i understood that it was only on early B8 models (2010-2011 ?). It is plug in the S/C loop between sc and electric the pump. It's a sort of pre-cooler for the #3. HX.

5. The Famous "ADS Cooler". This is a heat exchanger to cool the steering fluig (oïl) of versions specifically equiped with the "dynamic steering" option. It is only for the B8 models, as B8.5 models have Electric steering assistance.

6. Engine Oil cooler. This device is attached to the engine block. The engine oïl exit in this plates exchanger where the engine cooling water flows through it. The Water heats up the oïl at cold start/bormal driving, and then the water cools oïl when spirited driving.

Hope this will help.

Please feel free to react to this first post, if there are mistakes to adress or clarifications to add.

Best regards

Mathieu

[Loe]

Makes sense, I was very confused by peoples referencing in previous thread, but your chart cleared it up nicely!

[chaos2984]

all B8.5's don't have the Aux water cooler either. They deleted it.

[Mat@1975]

all B8.5's don't have the Aux water cooler either. They deleted it.

Yes, it's a pitty...
It could really lower IAT more. Don't understand why they put it and then deleted it...

Maybe one could buy all the parts of this cooler (support, air guide , hoses, and cooler) and then install it ? It could be a nice improvement then?

BR

Mat

[nunzo]

so do the 2010-2011 b8s show lower IATs compared to later models?

[Mat@1975]

so do the 2010-2011 b8s show lower IATs compared to later models?

Good question !

They at least must show more heat soak resistance.
It's exactly lika adding an additional tank like in the APR, AWE, ... cooling kits...

BR

Mat

[Mat@1975]

First thread edited with engine oïl cooler.

[AmanG]

Is the oil cooler present in all model years?

Sent from my SM-N910V using Tapatalk

[Mat@1975]

Is the oil cooler present in all model years?

Sent from my SM-N910V using Tapatalk

I would be surprised if not. it is really a part of the engine.


BR

Mat

[Laurent21]

To complete Mat's post, here is a picture of the oil cooler, taken from my car.

[cspcrx]

I think all 2012s have the extra cooler for the SC. Mine does, just not sure if there was a clean cut when they went to the B8.5 facelift.

[BernanksBeard]

The b8 uses a single pass front heat exchanger and the B8.5 uses a dual pass front heat exchanger. I bet they are pretty close in performance.

[miztahsparklez]

2012 has the cooler in the driver side for sure. I think the cost to add this would be more than getting a larger exchanger to start.


Sent from my iPhone using Tapatalk

[cspcrx]

The b8 uses a single pass front heat exchanger and the B8.5 uses a dual pass front heat exchanger. I bet they are pretty close in performance.

Until you add an aftermarket unit like your AMS then the B8 would technically have more cooling than a B8.5. As someone else posted I am curious if anyone ever measured that. Two identically tuned and outfitted cars, B8 and B8.5, in the same environment to see if the IATs are different.

[chaos2984]

Until you add an aftermarket unit like your AMS then the B8 would technically have more cooling than a B8.5. As someone else posted I am curious if anyone ever measured that. Two identically tuned and outfitted cars, B8 and B8.5, in the same environment to see if the IATs are different.

well not exactly if the B8.5 is double pass like someone has said. If you have that side radiator and a single pass main radiator you would probably get the same cooling effect as a double pass one. I bet the temps are very close to each other. The probably went to a double pass to save money with costing a little more but they are saving with the parts deletion.

[cspcrx]

Perhaps when stock.

But when you remove the stock cooler and replace it with an aftermarket unit like one from AMS, APR, AWE, etc. that advantage is gone. They will then have the same primary cooler but the B8 will have the precooler that the B8.5 wont have.

[acsgp]

The b8 uses a single pass front heat exchanger and the B8.5 uses a dual pass front heat exchanger. I bet they are pretty close in performance.

Thinking aloud, would upgrading the B8 cooler to the dual pass B8.5 version, + the aux cooler lower the temps even more, without having to go all Cold Front? I like OE upgrades.

[amz]

Thinking aloud, would upgrading the B8 cooler to the dual pass B8.5 version, + the aux cooler lower the temps even more, without having to go all Cold Front? I like OE upgrades.

I just had the same thought. Can anyone send pics of a naked B8 radiator vs. B8.5? Hopefully its "plug and play"

[miztahsparklez]

It's not the hoses and locations are different. It's also probably just as expensive.


Sent from my iPhone using Tapatalk

[colby7]

Perhaps when stock.

But when you remove the stock cooler and replace it with an aftermarket unit like one from AMS, APR, AWE, etc. that advantage is gone. They will then have the same primary cooler but the B8 will have the precooler that the B8.5 wont have.

The aftermarket products don't replace the stock units. They work together.

[derek.kritz]

Lot of good info here...never knew that the supercharger water cooler was that small. Obviously the engine coolant and supercharger coolant is shared in the stock system. So, if I was to upgrade to, say, the revo unit, that just consist of the the larger heat exchanger and an additional coolant tank, the coolant is still shared through the whole system no??


Sent from my iPhone using Tapatalk

[Mat@1975]

Lot of good info here...never knew that the supercharger water cooler was that small. Obviously the engine coolant and supercharger coolant is shared in the stock system. So, if I was to upgrade to, say, the revo unit, that just consist of the the larger heat exchanger and an additional coolant tank, the coolant is still shared through the whole system no??


Sent from my iPhone using Tapatalk

Hello,

APR, AWE are divorced systems. I think REVO and Forge also.
Not sure about Alpha.

BR

Mat

[Mat@1975]

Thinking aloud, would upgrading the B8 cooler to the dual pass B8.5 version, + the aux cooler lower the temps even more, without having to go all Cold Front? I like OE upgrades.

I just had the same thought. Can anyone send pics of a naked B8 radiator vs. B8.5? Hopefully its "plug and play"

It's not the hoses and locations are different. It's also probably just as expensive.


Sent from my iPhone using Tapatalk

Hello,

APR, AWE are divorced systems. I think REVO and Forge also.
Not sure about Alpha.

BR

Mat

I had the same though also, about the add. cooler.

It seems that a lot of parts are involved, i will rough estimate the cost this week end...

https://www.partsbase.org/audi/audi-...l-coolant-rad/

Best regards,

Mathieu

[miztahsparklez]

I have the PLM exchanger. Probably one of the best mods I have. The car always feels quick, even on a hot day. I wouldn't spend all this time on labor just to get marginal performance.

Oem might be great in your mind, but OEM has also failed in the cases of rocks going through and puncturing the cooler. The same can happen to the aftermarket ones, so just because it's OEM in this case, doesn't mean it's better.


Sent from my iPhone using Tapatalk

[Mat@1975]

Hello,

Took a look on the parts costs.

A rough estimate is 350-400 € for the major parts of this additionnal cooler (hoses, brackets, cooler,...) excluding clamps, nuts, ...

Seems a good bang for the bucks ?

BR

Mat

[acsgp]

I had the same though also, about the add. cooler.

It seems that a lot of parts are involved, i will rough estimate the cost this week end...

https://www.partsbase.org/audi/audi-...l-coolant-rad/

Best regards,

Mathieu

Great, thanks Mathieu

Best
Andrew

[derek.kritz]

I have the PLM exchanger. Probably one of the best mods I have. The car always feels quick, even on a hot day. I wouldn't spend all this time on labor just to get marginal performance.

Oem might be great in your mind, but OEM has also failed in the cases of rocks going through and puncturing the cooler. The same can happen to the aftermarket ones, so just because it's OEM in this case, doesn't mean it's better.


Sent from my iPhone using Tapatalk

The PLM exchanger is definitely in the conversation for me. I have not heard anything but great reviews on it. Do you have the the expansion tank as well? I'd really like to get REVO involved in a group buy. I really like the look of it.


Sent from my iPhone using Tapatalk

[miztahsparklez]

The PLM exchanger comes with an aluminum tank. I don't think I needed another reservoir to divorce it from the stock cooling system.

PLM comes with all the hoses and clamps for both b8 and b8.5.

After doing the work, it's something I'd rather do only once. Don't skimp out on trying to just do OEM. The benefits just aren't there.

I would say get any of the exchangers you can get for the best price. They will all perform around the same, unless you're into road racing or something, where that fraction might actually matter.


Sent from my iPhone using Tapatalk

[derek.kritz]

The PLM exchanger comes with an aluminum tank. I don't think I needed another reservoir to divorce it from the stock cooling system.

PLM comes with all the hoses and clamps for both b8 and b8.5.

After doing the work, it's something I'd rather do only once. Don't skimp out on trying to just do OEM. The benefits just aren't there.

I would say get any of the exchangers you can get for the best price. They will all perform around the same, unless you're into road racing or something, where that fraction might actually matter.


Sent from my iPhone using Tapatalk

Cool. I just asked about the expansion tank cause I see that they sell the exchanger with and without the tank. U obviously got the one with the tank.


Sent from my iPhone using Tapatalk

[miztahsparklez]

I got mine in a deal lol. Didn't know they had another flavor without it.


Sent from my iPhone using Tapatalk

[acsgp]

After doing the work, it's something I'd rather do only once. Don't skimp out on trying to just do OEM. The benefits just aren't there.

The benefit for me via the OE upgrade route is that the authorities here are pretty anal, and we have to send our cars for semi-annual inspections. One of the reasons why I went for the Q5 3.0T calipers instead of the 6 pot StopTechs with a 355 disc.

The PLM exchanger comes with an aluminum tank. I don't think I needed another reservoir to divorce it from the stock cooling system.

PLM comes with all the hoses and clamps for both b8 and b8.5.

After doing the work, it's something I'd rather do only once. Don't skimp out on trying to just do OEM. The benefits just aren't there.

I would say get any of the exchangers you can get for the best price. They will all perform around the same, unless you're into road racing or something, where that fraction might actually matter.


Sent from my iPhone using Tapatalk

Great, thanks for letting us know your experience. One thing about the PLM system - with the increased coolant capacity, why isn't the pump upgraded.

[miztahsparklez]

PLM is almost identical to another brand. That brand's reasoning was because it didn't actually change the performance much if any. Not sure if it was just a cost cutting measure or if that's really the case.


Sent from my iPhone using Tapatalk

[cspcrx]

The aftermarket products don't replace the stock units. They work together.

Yes they do. The aftermarket coolers completely replace the stock supercharger cooler. That is my point. At that point both the B8 and B8.5 have the same primary supercharger cooler but the B8 will have the additional pre cooler that the B8.5 does not have.

[Loe]

out of curiosity, with a divorced system, what type of fluid are you all using for the S/C coolant?

[cspcrx]

I looked at my car for the loop, I do not see it. Specs are in the sig. When I switch between comfort, dynamic and auto I can feel the difference in the steering so I know it changes. Is it in front of the radiator? Perhaps I am just missing it.

[infinkc]

out of curiosity, with a divorced system, what type of fluid are you all using for the S/C coolant?

stock coolant G12

Since we are on the topic of the heat exchangers, has anyone done a killer chiller yet?

[Mat@1975]

I looked at my car for the loop, I do not see it. Specs are in the sig. When I switch between comfort, dynamic and auto I can feel the difference in the steering so I know it changes. Is it in front of the radiator? Perhaps I am just missing it.

Hello,

I think you can't miss it.
If you don't have it, it means you don't have the "dynamic steering" option. However, to have the ADS able to set the steering more or less stiff.

Dynamic steering is not only able to stiffen the steeiring, but it also changes the "gearing" of the steering. ie, in dynamic, you need less steeering inputs to have the same wheels turning.

I don't know if it's clear... ;o)

BR

Mat

[theswoleguy]

stock coolant G12

Since we are on the topic of the heat exchangers, has anyone done a killer chiller yet?

this with a divorced system would be silly. winter year round

[cspcrx]

Hello,

I think you can't miss it.
If you don't have it, it means you don't have the "dynamic steering" option. However, to have the ADS able to set the steering more or less stiff.

Dynamic steering is not only able to stiffen the steeiring, but it also changes the "gearing" of the steering. ie, in dynamic, you need less steeering inputs to have the same wheels turning.

I don't know if it's clear... ;o)

BR

Mat

Makes sense need to look at the build sheet.

[Evan2]

I just found out my used s4 has GIAC stage 2. I have Intake and Exhaust plus some suspension mods, now that I do not have to spend the money on a tune I wanted to look into cooling mods. I am currently stationed in Great Falls, Montana. So very cold winters and summers in the 90s, I am at 3300'. The issue is that we can get stationed elsewhere whenever the AF decides its time for us to go. I really only do some spirited driving around town and have a 4 min drive to work. I assume I can forgo these mods for now but wanted to look into it. What is the most cost effective route I could go now? HE?