Heya, so basically, you’re seeing a 20 degree difference with the RMR cooler, in most conditions across the board?
That would be correct. Shocking really.
Ok more fun with graphs!
Let me set the scene. Yesterday I had to drive out to the middle of nowhere Mexico for a freelance shoot at a brewery. It was, perhaps, one of the most beautiful days ever. Temps in the low to mid-70’s Fahrenheit and not a cloud in the sky. The road leading to the middle of nowhere is a fairly undulating “fast” road. Nothing tight at all and it’s mostly high speed. I’d hammer it out and back which would enable me to get a different look at how the cooler performed.
Best laid plans.
An eighth of the way in on the testing road, I ran into construction. This would be the norm for the next 20 miles. It wasn’t just any construction, it went from a two lane to a one lane with extended stop periods while traffic heading the other direction came through. They even set up stoplights but those only added to the time sitting.
Great. Plan out the window. I get to my freelance assignment and find out they forgot to call and cancel as the power went out. Really??? Ok. Beautiful day and I saw some choice spots for car photos. All is not lost.
I decided to see just how hot I could get the transmission. I logged the entire trip back. The log is over 1.6 hours in length. Seriously.
I started out at the brewery. Beautiful building, I’ll use that as a backdrop. I positioned the car and left it running while I got out and shot photos. This lasted for a good half hour.
Once under way, the first half was nice and fast, no traffic, no construction. It was all high speed so there was a lot of airflow. Predictably, I was always running about 66C on the transmission temps, 80 on the clutch and gearbox.
Once I hit the scenic spot, I pulled over, left the log and the car running and proceeded to shoot. I found several locations and never turned the car off.
To my surprise, the temps remained in the cool range, only rising to 74 degrees after an extended period of time. It mostly stayed in the 60 degree Celsius range.
Hitting the road again, I hammered it until I came to the construction zones and invariably, other cars. At each stopping point, I purposely left the car in gear to watch and log the trans/clutch temps to see what they did. Both rose, slowly, to a point. Typically, sitting, car in D, the clutch would rise quickly into the 90 degree C range, but would stop around 94C max. And it’d stay there. Far different from the OEM cooler which would continue to rise into the 100’s. Once moving, the temperatures would all rapidly drop. The manual gear oil would drop in temp with every stop (predictably) so there’s definitely some heat transfer happening between the ATF and MTF side.
Overall, I was expecting temperatures to get much hotter when stopped or idling in D mode. It didn’t happen. It may be due to the Setrab cooler’s size and being able to radiate heat to the surrounding air. When I was shooting, I did not hear the car’s fans running. My typical oil temps were in the 222F range, fairly consistently. The car always runs hotter in mild and cold temps. If I could just get it to run at 206F all the time…I’ll save that for the next mod.
Graphs! This is the entire 1.63 hours. You can click on any of these and make them larger.
Here’s a closeup of the graph color guide.
Here’s a closer view of the entire 1.63 hour graph.
This is when I first started the car back up and was positioning it to take photos at the brewery. Notice the car is mostly at idle (white line on the top graph). The temps come down as the fluid circulates through the cooler and they stay almost completely steady the whole time. The a/c is NOT on.
Here’s a closeup of the “fast” section. Note, white is rpm on top, with white on the bottom being vehicle speed. Like I said, in Mexico. The only downside is it was mostly a 5-7 gear situation. Not a lot of acceleration to redline through all the gears. These are tiny “B” roads as they call them in Europe and quite rough in spots.
Here’s the “scenic” section. I was flying, came upon a few good spots to shoot, pulled over and left the car running.
This is a closer view of the construction section where I had to come to a complete stop, leaving the car in gear.
This is a slightly expanded view of a section of the above graph so you can see more detail. Overall, I’m completely happy with the way the cooler performed without the fan.
That’s great news looks like its doing the job without the fan packs ! It just show you that by it not running past the coolant in the rad and just having it run through a separate cooler is enough to keep the temps lower and more stable. Great work there getting all the graphs together its very interesting and i love the little story to go with it sounds like you had fun lol !
I’m really kind of surprised but I’ll continue to monitor in different situations. This would be a very “American” situation but I can see the trans temps getting higher if you were to say get stuck on the highway while commuting in between San Antonio and Austin where you’re creeping along really slowly and stopping for long periods frequently. The fan pack is for the worst case scenarios and at the drag strip too. Its 100% foolproof.
I was helping an S5 owner with a trans cooler a while back. He’d already sourced his own Setrab core, different size, with a fan pack as well, but was using my cross bar to mount it. His idea was to hook it up to a digital gauge made by Aeroforce and use it to set a different temp for the fan pack to come on. I don’t think he’s gotten back around to working on it again but it was a neat idea and I may actually pick up one of those gauges regardless. https://www.aeroforcetech.com/products_interceptor.html
The system I use is automatic and has a thermal core which connects the circuit when temps get above 80C causing the fans to come on . With the gauge, you could theoretically set it at an even lower temp. There are no thermal triggers, like the one I use, which trigger at a lower temperature. 80C is as low as they go as they’re mostly designed for oil systems.
Wow that sounds ace and a good idea, but what would be the advantage of the Aeroforcetech apart from setting it lower than 80c how much lower would you want to go ? Is there an optimum temp for the ATF and is it lower than 80c if not then what you have already does the job does it not ? Unless there is more things you can do with the Aeroforcetech like pre set temps in stages depending on what your doing in the car ie drag strip or tight and twisty’s or traffic jam then all you would do is select a temp you want it to be at.
As for the testing your doing now i get what your saying if your stuck in that sort of traffic then yes you might see temps rise up, for that it would be great like you said to have the oem fans cut in to bring it back down, but saying that so far so good and its a surprise how well its doing so you never know it might surprise you with this situation !
Yeah it does a ton of stuff. One idea, for the drag guys, would be to just have the fans come on when in the pits. Could work with the road race guys too. Could cool down the half liter of fluid in the cooler and be ready for the next run. But you could set them to come on at 70C instead, providing that much more of a cushion when at the track and not moving. Optimally, you’re probably looking at 60-90C. The clutch seems to like 80C range. Rarely see it drop below that.
I kinda wonder if I can configure the car’s fans to come on with it. Might have to reach out to them.
Yeah it sounds good to me if it can do all these things it would be a big bonus for the drag strip, stuck in traffic and even track as like you say 70c would give you an extra 10c cooler running temps !!
There must be a way to get the fans to come on and off with this Aeroforcetech well worth looking in to, see what you can find out.
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Hi Ape,
Being a member of A5OC for years and not getting any good info or answers at problems there except costs a lot… Searching for a transcooler and info on the DL501 brought me to here…
I own a 2011 Audi S5 Sportback CAKA and somewhere I read that you where checking into a transcooler for the S5… I wanted to see what your thoughts are on the following:
Getting myself ready to do a Mechatronics rebuild (P179D) and spending lots of time diving in to the heat issues and failures of it, made me wonder why it does not have a dedicated oil cooler. (I have the P179D error and logging livedata with Carista (Yes the last update will give you live data on trans temp) on the transmission temp, the car makes me sweat to get it over 90c. (I have cleared the fault past startup of the car, but might be a hidden small limp/save mode is still active))
So my thoughts at the moment:
Transmission:
Change oil flow to dedicated oil cooler from Hel or Setrab to RS5 style right lower grill location
(This will decouple the oil cooling from the front radiator/ heat exchanger)
Engine:
Change oil flow to dedicated oil cooler from Hel or Setrab to RS5 style left lower grill location
Supercharger:
Supercharger oil flow to optional ADS cooler
Engine Coolant:
Change OEM radiator/ heat exchanger flow so the coolant can flow extra through the old oil loop
The idea came up that making the oil system separate:
- Will drop the loads on the front radiator, lowering the supercharger cooling IAT temperatures
- More cooling for the DL501 to make it more reliable
- Better engine cooling
- Less risk of mixing coolant with engine oil
Has anyone had any experience on this mods or thoughts to swap out.
(Typing this out makes me feel like the Mad Scientist they give at work might be true)
I have searched a way to DM it to you, not found a way… Maybe cause I am a new puppy member haha
So first, you’re in luck. I’ve just started processing the first two S5 transmission cooler kits. Assuming everything is the same on the 2011 (are you across the pond?) then it should work just fine.
In addition to the actual transmission cooler kit, I have new brackets to connect and mount aftermarket heat exchangers for the 3.0T to the RMR cross bar. I actually posted this up in the S4 thread here with photos here:
This is, obviously a full-divorced system and it does free up radiator capacity to cool the engine.
I would highly suggest ditching the Carista and getting a Ross Tech VCDS. It’ll not only log faster but it’ll show you ALL of the transmission temps (there’s four you can monitor) and it’ll allow you to go into individual modules and clear codes instead of just doing it globally. That method doesn’t always work for some issues.
There should be an ATF side cooler for the transmission. It’s housed on the left side (in the U.S.) of the radiator and it’s a liquid to liquid heat exchanger. In theory, it helps heat up the transmission fluid sooner and then once up to temp, it cools the transmission fluid as long as the coolant in the radiator is at a lower temperature. In reality it doesn’t do either very well.
If you have NO ATF coolant lines on the 2011, you’d probably have to retrofit the later filter housing and ATF coolant lines.
Shoot me an email too, redmistracingllc@icloud.com and we can get a discussion going and you can share a few photos.
Hey Ape,
Thanks for the quick answer!
Yes I am across the pond… VCDS and a laptop on the passenger seat is not allways nice for daily driving. I have VCDS, Odis-S and Odis-E.
This is a schematic of the cooling system, I just do not have the side radiator:
Here are the pics of my car:
You’d have to take the front bumper off. The transmission cooler is located IN the main radiator. The RS5 is the only model that has the two auxiliary side radiators. The S4/S5’s here in the states don’t have them. Let me pull up Etka and see if I can find the right diagram for your car.
Looks like you have the same setup as the U.S. cars. If you open the bonnet (you may need to remove the intake) and look down on the left side of the radiator, you’ll see the upper coolant line where it attaches to the radiator. Here’s the Etka diagram.
It’s hose #15 which connects at the top of the radiator and #12 on the bottom.
Thats why I wanted it relocated RS style in the lower grill and reduce load on the main radiator.
Yeah you could do that but airflow is critical. You’d need a duct leading to and from the heat exchanger core for whatever purpose be it engine oil or a transmission cooler.
With my system, the cross bar is about 1/4 of the surface area of the OE crash bar. This lets in additional flow. The transmission cooler is positioned in a way that promotes airflow through it instead of around it. With the additional airflow provided by the cross bar, you’re really not limiting the air cooling charge to the HX or the radiator.
This would still give you room for an additional oil cooler setup in front of either wheel. But again, if you do that, you have to make sure air has a way to flow in and out of the core and you’ll need to modify your wheel well liner with an exit duct at the very least.
The B8 S4/S5’s had a left side aux radiator and the heat exhanger in the front had a cooling line going in from one end and coming out the other end like the one shown through the grille in Elemo299’s pic. The Aux radiator was standard with a Hot weather option which all N. American cars had a standard. When they did the B8.5 Audi dropped the Aux radiator in the N. American market but the heat exchanger in front for the Supercharger got a little bigger and both inlet & outlet were on the left side so the only other difference is pipe #6 in the diagram above comes down from the supercharger and both lines curve to the Left.
Latest batch is done, I have four left and not spoken for if anyone is interested. Just shoot me an email, sales@redmistracing.com or purchase directly off the website.
I also have these available for the S4 and S5 3.0 cars as well.