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      10-02-2011, 04:29 PM   #123
Alpina_B3_Lux's Avatar

Drives: Audi R8 V10, BMW 530d xDrive
Join Date: Feb 2008
Location: Germany

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2009 335i  [4.45]
REVIEW: AR Design aluminium radiator

22. REVIEW: AR Design aluminium radiator


If you've read one or more of my reviews so far, you will probably have realised that I track my car regularly on the Nordschleife of the famous Nürburgring. Now, a 335i isn't really a track car, which is why some efforts are needed to make it at least reliable on a track (from an engine perspective; suspension and other stuff I will let aside here). As a forced induction engine, this means in particular that things need to be done to improve the cooling system of the car. The N54 engine that my 335i is powered with has two cooling systems, one with oil and the other one with water. Both also cool the two turbos that push air into the combustion chambers, which makes it even more critical to maintain reasonable temperatures in both circuits.

The stock oil cooling system of my car, which is in particular inadequate if you increase the power output of the car and/or track it, has already been substantially improved over the past two years, by installing an additional oil cooler from AR Design as well as upgrading the stock oil cooler with a bigger Setrab core. As a consequence, limp modes from too high oil temperatures are excluded.

But what about the water cooling system?

Actually, BMW itself gives you the option of installing an additional water radiator together with the - very mild - BMW Performance tune. That implies that the BMW engineers believe that the stock water cooling circuit needed upgrading in order to cope with a higher power output of the engine which automatically also increases its heat load. Which is certainly true: In the track section of this forum, you can read quite a bit about water temperature induced limp modes (see here: 335i limpmode party at the track), and a friend of mine also experienced one when doing 7 hot laps on the Nordschleife.


As a result of BMW Performance offering the additional water cooler, my first thought was to source the part for this BMW Performance water cooler and install it in my car. However, a friend of mine had already done this and still reported problems (including limp modes) with his car when tracking it. Therefor I decided not to go down this route, also because I was rather unsure whether the additional radiator would actually fit in the driver's side wheel well of my car, with the STETT cold air intake that already took up quite a bit of space down there.

Then I heard that AR Design was developing an all-aluminium radiator with much bigger capacity than the stock (plastic) radiator. As all AR Design products I've installed so far (two sets of downpipes, oil cooler, oil catch can) were well designed and until today functioned flawlessly, I decided to give that a try.

After some waiting for the final product to be released, there it was (see here: Announcing the ar design all aluminium Performance radiator. Here are some of the features:

• Made from aluminum, including extra thick, heavy duty end tanks
• Plug & Play OEM style connectors for radiator hoses
• Fan shroud designed to re-use OEM computer controlled fan
• 100% TIG-welded
• Individually pressure tested
• Re-uses factory mounting point
• Drain petcock
• Two rows of 1" thick tubes for maximum cooling capacity

That sounded very good and seemed to respond to my needs exactly - a replacement for the stock radiator that fit with the OEM connectors and without having to modify the factory mounting point. I ordered it and got it in the mail after a few weeks - well packaged as usual:

Aluminium radiator - packaging:

Aluminium radiator - mostly unpacked:

Here are some photos - from AR Design - of how it looks unpacked:

Aluminium radiator - front:

Aluminium radiator - back:

Aluminium radiator - side view:

It was actually quite big and heavy! But looked also well made, as far as I could judge that without being an expert for aluminium welding.

I therefor made an appointment with my garage (Daum Motorsport) for its installation.

Unfortunately, here the problems began…!

First problem - bad fitment (1)

A day after having dropped off my car, my garage called me and told me that there was no way to fit the radiator as it interfered with the intercooler tubing. Also, due to its greater height compared to the stock radiator it stuck out a bit over the edge of the engine bay. The latter issue could be ignored, but the former prevented any installation of it in its current state:
There was no way that it could be made to fit, safe removing and redesigning all intercooler tubing which I obviously did not want to do as it would have been even more of a hassle. Also, it would seem that then there would not be any wriggle room at all for the intercooler tubing, and it couldn't compensate for engine movements or largening of the tubes in size at full boost.

I've tried to make some photos to illustrate this point, although because of the extremely tight fitting it's a bit difficult to see:

Radiator interfering with intercooler piping:

Of course, this was contrary to what AR Design claimed - stock mounting point, Plug&Play installation. I wrote of course to Andrew @ AR Design pointing out these design flaws, but aside from stating that they could not test "every single intercooler available with our radiator before shipping" (which was not the point at all as the design interfered with the stock intercooler piping, not any aftermarket piece), nothing more came out of this exchange.

The radiator therefor had to be removed again from the car (some more hours and €€€), and my shop had to cut off the radiator outlet tube on the passenger side that was not correctly designed and weld it on again slightly higher and at a steep upwards angle (more €€€). That eliminated the issue with the intercooler tubing that was in the way and which interfered with the above mentioned outlet tube. Then the radiator itself was re-installed again (more €€€).

Second problem - bad fitment (2)

However, upon installing the radiator, it was discovered that there was another, however minor, issue: On the driver's side one of the struts on the backside of the radiator (basically the fan housing that you can see on the photos hereabove) interfered with the charge pipe tubing on that side (again the stock piping, not any aftermarket one).

On the following photo you can get an idea of what I mean:

Radiator - fitment problem (2):

This one also had to be rewelded and moved slightly in order to be able to properly mount the radiator and not interfere with the charge pipe tubing. Again, more €€€ and time spent to correct that issue…in total I believe that the install, uninstall, re-install and rewelding process has cost me around as much money as the radiator itself - 1000 USD.

Here's a photo comparing the stock radiator and the AR Design one - you can see the difference:

And here's how it looks installed, after all the fitment issues had been resolved:

Aluminium radiator - installed:

AR Design confirmed that they had changed the design of the radiator so that - as opposed to my obviously beta unit - the next units would not have these design flaws.


Now, after going through all that hassle, was there at least a significant improvement to be felt?

The first major difference I noticed was that the car took much, much longer to reach its operating temperature (judging from the oil temperature gauge). Where before it took around 5 minutes of driving to get to around 100 degrees Celsius, it now took more than 10, in colder weather even 15 minutes before that happened. So, obviously, the radiator did what it was supposed to do - provide more cooling to the engine.

When on the track, I did some datalogging with the BT tool and the water temperatures stayed significantly lower than before. Unfortunately, due to an IT incident these datalogs were lost, otherwise I would be able to provide you with more and more precise data than this.

As the installation was done in September 2010, the tracking season was almost over, so that I didn't have more than one opportunity to actually drive the car with the upgraded radiator on the track. But during that one session I could indeed notice a significant improvement in terms of water temperatures - so it seemed all was as it was supposed to be.

Or not?

Second problem - leakage

During the winter (beginning of 2011) I suddenly noticed the dash warning telling me that the coolant level was low. As I had never received such a warning before, I left my car at my garage (who had done the install of the radiator) and let them check it out. After removing the undertray they immediately saw that a significant amount of (blue colored) coolant had leaked out of the aluminium radiator. It looked like there were at least two leakage points at the back of the radiator, within the mesh. Due to the constrains in terms of space in the engine bay it was however difficult to make out details.

Here are some photos where you can see a few blue drops on various parts of the engine:

Coolant (blue) leaking out (1):

Coolant (blue) leaking out (2):

My garage removed the radiator and confirmed the two leaks, at the back of the radiator within the mesh that you can see behind the fan housing. Due to the leakage points (within the mesh) it was not possible to repair the radiator, such as by welding (the mesh cannot be welded). I therefor asked the garage to remove the radiator and install the stock radiator again.

Vendor's reaction?

Of course I contacted AR Design about this (in May 2011). Having dealt with them before on several occasions with different products, I've always had a very good feedback time and response from Andrew and his team (except the aforementioned fitment issues).

Unfortunately, not this time.

First, they ignored my messages for about two weeks. Several reminders didn't change that - only after I posted my experience here on the forum I finally got an answer (end of May 2011), and an offer to replace the faulty radiator.

That would not have compensated me for all the installation €€€ I had to spend again for removing and re-installing it a first time, and then a second time when the replacement arrived. However, I agreed to this.

Which is where we stand now - several months (and reminders) later, no reaction from AR Design and no replacement or compensation.


To my regret I therefor have to state that I cannot recommend this radiator to anyone - I have yet to see proof that the design issues have really been remedied, and it seems that there were (maybe still are) problems in the quality control of the manufacturing process.

Also, this experience has left me very doubtful about the attitude of AR Design to its customers and, in relation to the present issue, was greatly disappointing to me.

I will post updates here on whether - or not - any replacement or compensation will ever arrive. Of course I also invite AR Design to explain (maybe even apologise, who knows) this antithesis of customer-minded attitude.


As a consequence of the present post, a refund has been made which covers most of the initial price of the radiator that I paid.
Audi R8 V10; sold: BMW 335i

Last edited by Alpina_B3_Lux; 10-03-2011 at 05:59 AM.