Me vs my 2006 Audi A4 Quattro 2.0T Part III: The S3 K04 Installed!

So the S3 K04 needed some modifications to fit on my 2006 A4, including:

  • Diverter valve relocation since the turbo was not machined for it
  • Drilling and tapping the turbo for the diverter valve to have a place to inject air into when active
  • A custom charge tube, which now connects to the top of the intercooler instead of the bottom
  • The bottom intercooler transfer line being clocked at a different angle so it can now connect to the bottom of the intercooler
  • K04 exhaust flange is larger than the K03, so weld holes and drill+tap new ones (in stainless!)


Custom Turbo Charge Pipe

Custom Turbo Charge Pipe

This is the mostly finished product, you can see the custom diverter valve mount with a rubber tube that hits a 3/4″ NPT nipple that was added to the turbo before the compressor wheel.

Divert Valve Relocate Body 1

Divert Valve Relocate Body 1

The diverter valve relocate was made entirely from Schedule-80 tube, from the 1″ tube connecting at the bottom flange and and side flange (for the re-circulation tube) to the 2.5″ tube that brings it all together. Everything has been opened up mildly on the lathe, you can see the lip left over from the original thickness.


Divert Valve Relocate Body 2

Divert Valve Relocate Body 2

The top view shows the lip a little better, along with a slight angle cut to make welding the top flange for the diverter valve easier. The 1″ pipe entering this pipe was cut on a ~$45 end tubing cutter from Harbor Freight which worked better than expected.

Divert Valve Relocate Assembly 1

Divert Valve Relocate Assembly 1

Here’s a quick mockup of the assembly. I did mockups in PVC before machining anything.. partially because I was bored, partially to make sure my ideas would work correctly. The plate on the “top” of the relocate will have the small hole drilled out to 1″ to fit a coupling into the intake charge tube. The other long 1″ pipe actually seen in the picture will be cut short to allow for the recirculation hose to connect to the turbo.

K04 Modified Flange

K04 Modified Flange

The flange, modified. The outer bolt hole you can see in the lower left is the original K04 size. The other side needed to be cut off to avoid hitting the motor mount. Unfortunately I had some issues drilling the new top two holes after welding it, probably due to the type of rod used. The studs wound up getting welded in, but the important part was we now have a flange that fits the stock catalytic converter or 2006 A4 downpipe!

The car runs, at first it ran FAST and would pick up >15psi of boost with spikes above 20psi. It was pretty great, even if it was running lean. APR K04 tune incoming along with bigger injectors.

Keep in mind lots of stock parts needed tweaking, some of the oil/water lines needed to be bent slightly although they happily bolted up to the turbo.


Audi A4 K04 Installed

Audi A4 K04 Installed

The charge tube is a tight fit, it just about touches the radiator, AC lines, and the frame. I should’ve used 2″ pipe here instead of 2.5″ and tried to find some with tighter radii, but it worked out. Not the 2.5″->2.0″ reducer on the intercooler. I just welded some exhaust pipe on the core support to point it as well as I could at the intercooler, the silicone hose I used isn’t kinked so it appears everything turned out pretty good.

So my water pump replacement turned into replacing a water pump, timing belt, thermostat, and adding a bigger turbo. It also made me buy shiny new tools, like an Ingersoll Rand 2235Ti Max 1/2″ impact gun (WHICH KICKS ASS! 1350ft lbs of reverse torque — really?!), and of course “triple square,” tools and a few sets of security bit sets for Torx bits which I’d constantly drop and find later — and smaller triple square bits (like M5).

So Audi A4, I win today. Though I’m sure you’ll break some other way. But for now I don’t have a noisy turbo, and hopefully I’ll have lots of horsepower soon.

Me vs my 2006 Audi A4 Quattro 2.0T Part II: The Tale of Stuck Bolts, and the S3 K04 Turbo That Doesn’t Really Fit On An Audi B7 A4

DISCLAIMER: This is mostly a rant, not a how-to. I’ll post a “how I did it,” later — you know, once I actually do it. A good resource for the S3 K04 turbo on a B7 A4 and the parts you will need is available at Audizine Thread: S3 turbo on A4 2.0 Tfsi DIY:ish, there’s some good information on that post and of course throughout Audizine’s forums.

So, the Audi saga continues. After finding out I needed a water pump I ordered a timing set with the pump as it’s driven off of the timing belt on the VW/Audi 2.0T. I realized I had to take the nose of the car off, that’s everything forward of the fenders — core support, bumper, bumper support, headlights. I wasn’t fully prepared for how much of a pain that would be on a 2006 Audi with some stuck bolts.. but I did get it off, and I actually had access to the engine.

Changing the thermostat was now a possibility, so I decided to do that at the same time. As you may have read from Me vs my 2006 Audi A4 Quattro 2.0T Part I, Audi likes to make everything out of plastic. I actually couldn’t get one of the hoses free from the thermostat without possible damaging it, so I simply grabbed a pair of channel locks and crushed the thermostat. The pieces came easily out of the hose, and I didn’t have to buy yet another $110 hose (this one is semi-accessible without massive disassembly so I didn’t replace it for peace of mind).

After a few hours in the heat taking the car apart I decided to do something a little less intensive — I looked at my turbo caked in heavy oil deposits, and decided to match the S3 K04 turbo up to it. I had read that you needed a diverter valve relocation kit, but I could easily fabricate that. I wanted to make sure all the outlets were in the right spot.

They were not.

Of course they weren’t.


So here’s what APR offers as a K04 conversion package, with the outlets in all the same spots so you can reuse your factory hoses. I have a feeling they machine the K03 housing to accept the K04 compressor impeller.


APR K04 Turbo Upgrade for 2.0T Longitudal

APR K04 Turbo Upgrade for 2.0T Longitudal

Note how the turbo outlet (the pipe exiting the bottom of the turbo) points basically downward. The S3’s K04.. faces FORWARD! I didn’t do that much research, so I had no idea that I was getting myself into some fabrication.


Audi S3 K04 to A4 Overview

Audi S3 K04 to A4 Overview

Now take a look at the S3 turbo — you can see the long squiggly compressor outlet tube that they’ve fabricated and welded directly into the bolt-on turbo flange. You have to do that AND relocate the diverter valve. That tube is actually a good place to put the valve.

But I digress.


Further research after the fact showed what I should have known in the first place. Now my car will be apart longer since I’m not going to take the entire front end off again to change the turbo when that decides to bite the bullet next month. Of course now that I’m doing the turbo, my Tiptronic transmission will die. Mark my words. I bet it’s because of something made out of plastic, too.

Thankfully the inlet is in roughly the right spot and the exhaust manifold is actually part of the turbo, so I know it bolts up to the engine. The exhaust outlet is in the right spot, but I later found out the outlet flange bolt pattern is larger. That will necessitate some modification either to the turbo or the catalytic converter’s flange.

If fabrication scares you, if you don’t have a TIG welder, or access to a small machine shop — stay far away from the actual S3 turbo. The coolant and oil lines will bolt up easy enough, and obviously it’ll go right on the engine. But there’s no readily available turbo to intercooler charge pipe for putting an S3 K04 on an A4. Which means you have to cut up some pipe and do some welding (directly to the turbo’s outlet flange).

But the title says something about bolts, you say? Right. Audi had this great idea where they would put Allen-head bolts through the crank pulley into the crank, all the different types of bolts on this car befuddles me. They go from Allen to “Triple-Square” (12 point extrusion, similar to Allen) to Torx to good old fashioned hex head and 12 point bolts. Go figure.

Anyway, as my luck would have it I stripped two of those Allen head bolts. Considering the tight confines of the crank pulley and the fact that there were no edges to hit with an impact hammer or other tool I simply welded a 3/8″ bolt on to the first bolt and used a 9/16″ socket and the impact gun to drive it. It broke the weld at first, I couldn’t get good weld penetration due to the area constrictions. I ran it again and did my best to get a good weld around the circumference of the bolt.

I heard you like threads.. so we put bolts on your bolts.

I heard you like threads.. so we put bolts on your bolts.

It zipped right out. Bingo! The next one should be even easier, right?


It worked great for the first bolt, the second one was not so happy. I tried a 1/4″ bolt this time so I could actually sit it inside the existing stripped bolt. Sounds like a good idea, right? I was able to get a much better weld this way.. unfortunately this bolt I was welding it to was also a little more stuck than the last one, so the 1/4″ shank  simply snapped. I had more of a problem now since I also had to deal with the 1/4″ stub with a weld around most of it.

I welded a nut to what was left of the bolt. That weld snapped.

Then I remembered something great (and that I rarely have to resort to). I had recently bought a set of cheapo sockets that were basically junk – they broke easily. They were on sale for like $4, but even junk tools can have a purpose. This one was about to find out what its was.. because being a regular socket was certainly not it.

I cut three deep V grooves into the cracked socket with the bench grinder so I now had 3 prongs attached to the 3/8″ drive base. It fit fairly well over the existing weld material.

Three Prong Sacrificial Socket

I welded it up as good as I could and popped the impact driver on it, and out it came viagra 200.

Three Prong Socket Saves The Day

I still have to figure out how I’m going to get the large crankshaft bolt out which doesn’t want to seem to budge with my impact driver. Of course nothing about this car is easy!

But hey, now I can’t forget why I hated Audi.

Disclaimer #2: I actually kind of like the car, I just hate working on it as it was apparently engineered by people on massive doses of hallucinogens.

Disclaimer #3: Excuse my writing and rants, I’m running on little sleep.

Me vs my 2006 Audi A4 Quattro 2.0T Part I

The last month has been trying with this vehicle.. I hated Audis earlier in life, to which most people for some reason thought I was jealous. I wasn’t. There was a reason.

And this is the month that I’m reminded of it.

Quick background: I bought the car about 10 months ago and have had no problems with it aside from a miniscule coolant leak and some squealing from the turbo. Those things I was willing to put up with until it was warmer out. I ordered an S3 turbo which is a K04, I believe slightly smaller than the one on my 2007 Solstice GXP — but much bigger than the stock K03 and the same price as the puny stock one. And who could argue with more power, right? And I really don’t mind working on my own cars so long as I’m not fixing them. If I’m UPGRADING them, that’s a different story, right? So it got warm out.

So it all started when I went to put UV dye in my coolant system to track down this little leak that left no puddles or obvious signs, it was extremely slow. I hop in the car and go to drive it to get it good and hot and try to see if I can get my UV light and find some signs of the leak. Can you guess what happened within the next 15 minutes?

The car overheated. Quickly. I put the heat on, and that wasn’t working which told me I had just lost a massive amount of water. I was very close to home and decided to risk the 1/4 mile trip with as little throttle as possible. Audi likes to do this cool thing where they make everything out of plastic. Like coolant flanges on that bolt on to the back of the engine in a nigh-unreachable spot and connect the motor’s coolant passages to the heater hose and upper radiator hose and god knows what else.

Plastic is awesome.

Plastic is awesome.


This little piece of plastic took hours. And they break. All the time. Awesome design, Audi! It’s a cheap part, I think I paid around $20. Then I paid $100 for a new heater hose that connects to it just for peace of mind, and about $15 on another hose that’s about 4″ long (it’s probably one of the more expensive 4″ pieces of black hose you’ll run into).

So I somehow get the coolant flange in there and manage to get the hoses on it, I bolt the cam-driven vacuum pump back on and the high pressure fuel pump — I buy another emissions related hose and that sets me back $75 as the clips on mine broke. The PCV valve which is plastic, of course (and no it’s not a Positive Crankcase pressure Valve, it’s Audi’s ridiculous idea of Crankcase regulation) has nice hot oil fumes coming up into it — which make the plastic very brittle. I’ve already replaced it, but it seems to break with minimal pressure. Guess it’s getting changed again. I find out my valve cover is made of plastic and there’s a screw with the head broken off in it that holds the PCV valve..

I remember why I hate Audi.

I start the car, take it for a drive, everything seems to be OK until I get about 10 miles out.. the car slowly starts overheating. I try to bleed the outrageous coolant system. It doesn’t help. I notice there’s no water flow unless you rev the engine.. with a bled system a sure sign of a bad water pump. Which means you get to take the entire nose of the car off so you can change the TIMING BELT DRIVEN WATER PUMP!


Did I mention the OE water pump impeller is made of plastic and all the replacements are cast iron? Gee, I wonder why.

Thanks Audi. Clearly I was just jealous all these years. The cuts all over my hands are a testament to that. I’m so glad I finally own some kind of Audi.

In all seriousness though, it seemed to be very reasonably priced for a comfortable “AWD” (It’s not really AWD, don’t let that Quattro stuff fool you — the rear diff is open!) vehicle, and I couldn’t drive my daughter around in snowy weather in a rear wheel drive car with large tires — because they just act like big sleds and you don’t get to go anywhere.

This story continues with a horrible tale of a timing belt replacement.

And I ask myself — why did my 1979 Firebird need less maintenance and why was it literally over one hundred times faster to fix mechanical issues on it?

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