Fitting an Aftermarket Intercooler on my Golf 5 GTI.

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The Golf 5 GTI is a really nice platform to have as a project car. The amount of aftermarket upgrades is endless and you will lose yourself on the net finding what you want. I was always looking at what is the next step, what can I do to make the car run better and more efficiently. How can I get more reliable power out of the car? This is when I started looking at an aftermarket intercooler. On all the forums I found the common answer was S3 intercooler is more than good enough for a K04 setup.

I started thinking, the S3 intercooler is a good upgrade for a K03 platform that is modified. So how can the S3 intercooler be good enough for a KO4 setup, surely when you up the power on a K04 setup you need to go bigger on the intercooler. Even the REVO website recommended a bigger intercooler for the Stage 3 tunes.

So what are the options?

There are so many options out there, one of them is a twin intercooler setup. This is basically an extra intercooler that gets mounted in front of the aircon condenser and then the boost pipes split to and from the 2 intercoolers. This seems to work for a lot of people. I personally don’t like this setup, if the extra intercooler has less restriction than the standard or S3 intercooler then most of the flow will be diverted to this intercooler. The Air will not split evenly over the 2 coolers. This basically makes the standard\S3 intercooler useless for this setup. This setup is also top bulky and to many hose clamps.

The next option was a complete aftermarket intercooler that fits into the standard mount position. This is a nice clean setup. The issue is there are so many variants of replacement aftermarket intercoolers. They all may be similar size but they don’t all perform the same.

I spent a lot of time looking for the perfect intercooler. I came across the Wagner Tuning intercooler for TFSI platforms. Although this was one of the more expensive units out there the quality and function of this intercooler were of the highest standard.

So what makes the Wagner intercooler special

The core size of the intercooler is 610mm x 440mm x 65mm, the frontal area of the intercooler core is 10% larger and the core volume is 50% larger than the standard S3 intercooler. The end tanks of the intercooler are properly designed so that there are no restrictions. The Intercooler just flows perfectly. The pressure drop over the intercooler is so little compared to the S3 intercooler. Why does this matter? Well, the less pressure drop you have over the intercooler the lower speed the turbo has to spin to get to the requested boost by the ECU. This means lower discharge temps by the turbo.

This also gives more room for performance improvement, as you are able to run higher boost if you set the boost setting higher. The overall temperature drop over the Wagner intercooler cannot be compared to the S3 intercooler. The intake temps are way lower.

Does the bigger intercooler cause lag in the system?

You do get that if an intercooler is to be you may sit with more lag, in this case, it is not. In fact, the standard and S3 intercoolers are so restrictive, with the Wagner intercooler it will feel like the turbo is spooling up earlier and quicker. The Wagner intercooler will transform your TFSI engine completely. What is also nice that hot days when the car feels a bit lazy well that is a thing of the past. The power delivery will always be the same.

Installing the Intercooler

This is one more thing that makes this the perfect option for an aftermarket intercooler. You don’t have to modify anything to install the intercooler. Everything that bolts onto the standard\S3 intercooler bolts on to the Wagner intercooler in the same manner. The kit consists of new intercooler pipes that will reduce restriction even further.

You have to strip down the nose of the car, there are a few “how to..” documents on the internet.

Golf 5 GTI is stripped down to the point you can access the intercooler.

You have to strip the nose of the car to the position as indicated in the pic above. Then you start to loosen all that is attached to the intercooler. The intercooler is the part that is mounted to the framework of the car and the radiator and condenser are mounted to the intercooler.

As you can see in the above picture the Wagner intercooler is a lot thicker than the standard or the S3 intercooler. Everything fits perfectly and goes back together like standard. I would recommend being two people to do the job. I did it alone and it wasn’t fun. Taking the nose of an Mk5 Golf apart is not a one-man job unless you like swearing.

So what were my findings after first log tests

I got a handy tool. Anyone doing constant changes to the VW should get a VCDS cable. With this, you can check out for error codes and also do log runs to see if the car is performing better or not. The thing I noticed was my intake temps that used to be around 70 to 85 Deg C was now sitting at around 30 Deg C. You always want to be as close to ambient as possible. Engines just don’t like hot air. Because of this, I could change my REVO timing settings 1 setting up. I did my logs and the knock values that I saw were within factory spec.

The car felt absolutely perfect, I felt like a new car to me. The car pulled strong, and it pulled strong run after run, there was no heat soak it could notice. Fitting the Wagner intercooler to my Golf 5 GTI was one of the best things I ever did. All the testing I did with the new intercooler was done with the water-meth system disable as I wanted to see what the gains were with the new intercooler without the extra cooling of the water meth.

Now I could enable the watermeth and set it up properly to make the car even stronger.