K04-15 Turbo And all you ever wanted to know.


Staff member
Well this info is not for a debate on if it's worth it or not rather if you do and what you will need.

Uprated k04 files from GIAC - requirements
Required for all uprated files:
- k04-15 (duh)
- Upgraded exhaust
- Upgraded intercooler (SMIC or FMIC)
- Upgraded clutch
Required for pc-16 file (1997-1999.5):
- 3bar FPR according to GIAC, but "real world" reports recomend an adjustable FPR running at 2.7 or 2.8bar (google this for more examples)
- 310cc injectors
Required for j31 file (2000):
- 3bar FPR
- 310cc injectors
Required for Hammer file (2001):
- 3" OD MAF (from auid TT 225)
- 380cc injectors (from audi TT 225)
For more info on the k04 in the 2001 a4, including places to source parts and prices, check out my unitronic build thread here. Not required for files but nice to have:
- test pipe (ATP 3")
- larger Turbo Intake hose (ATP 3" TIP or Neuspeed xtreme intake hose)
- silicone boost hoses (samco if you want to pay full price, Zena Racing if you don't)

Parts info

2.5" exhaust, DP back - I think it was about $850 new (techtonics). $400 and up in the classifieds.
The turbo needs to breathe. Any bigger than 2.5" will be overkill on a k04 though. Some will say go with the 2.75, but that can lead to overboost, and I already have a 2.5" so I'm not upgrading right now. This is about doing a k04 for less money, remember?
3" test pipe - range from $75 to $125 for used, up to $160 for new.
The cat sucks power. If you can, get rid of it. The 3 inch unit bolts right up and you can really feel the difference. This part is readily available in the classifieds, so if you don't have one avoid paying full price. It's just a 3 inch tube! I got mine for $125 new, and it's an ATP unit. Custom is an option here, but you may have trouble due to emissions laws...
Diverter Valve - $50 to $70 used, up to $160 new.
Your diverter valve is old and tired. Pick your favorite brand and get it in place. Buy it used if you can find one in good shape, should run $50 to $70 for that. Otherwise they are on every tuner's site for $150-ish
ATP 3" TIP - $260 new.
So this baby is a 3 inch metal pipe, with one end attached to your turbo inlet and the other end attached to you MAF. It's great for two reasons. 1) It makes it nice and easy to plumb up your new 3" MAF, and 2) essentailly you're making sure there is no bottleneck and allowing the turbo to suck in as much air as possible with this baby. You're building an intake with a 3 inch MAF sensor housing anyway, so why stop there? Let it flow 3 inches all the way to the turbo. It won't starve for air without it, but you want it to be able to take in as much air as possible. For my money I'd always rather have a big metal pipe than a stock rubber piece or the samco, APR, or neuspeed upgraded units. They're not as bid, and in the end they're still rubber and can get soft, flex, crack, melt, and whatnot. Also, DON'T get this used. I bought one secondhand, and it was a disaster because it was missing pieces. Took three shipments from ATP, and cost me more than it would have to just get it from ATP new to begin with because they sent me the wrong stuff so I had to finish it with a home depot trip. It was worth it though, that baby has no problems suckin in air.
Parts Needed specifically for the Unitronic file:
k04-15 turbo - $300 - 500 used, $800 new.
I highly suggest holding out for a low mileage used turbo. They run between $300 and $500 depending on the mileage. If you can't, or don't want to risk not having a warranty, click here to get one the next best way... from Rippinralf @ Kinetic
Do NOT buy one of eBay for $200. They're not real, and will not fit properly. See the main k04 thread in the DIY/FAQ for that.

OE 225 TT 380cc injectors - $150 used, $450 new.
Why mess with things? Both files call for OE, and they're available. If you search, the going rate on 4T, Audizine, and Audiworld is about $150 give or take so hold out for that. They're not as scarce as people like to think. Unitronic specifically said to use them, so I'm sticking with their guidelines. If you can't find them your options are not as great as they used to be. All the pages say Genesis has discontinued their 380cc injectrs, but they're about $250 new if you can find them. Other than that GIAC mentions that Siemens Deka 1 380cc's work as well. If you're not going to get used parts out of the classifieds, talk to USRT as they have good prices and a great reputation around these parts.
A note on sourcing these (pay attention - this is a nice tidbit!): to find them you need to do two things. 1) watch the mk1 TT classifieds, and 2) post a WTB in the forced indcution classifieds. Don't post in the mk1 TT classifieds looking for the part. They have enough buyers coming to them, they're not going to find you and post for you. Plus if you wait you're going to get beat out for the injectors if you are not pro-active. The WTB in the FI forum will catch everything else... Geneis, Siemens, and even some TT OE injectors. I posted and injectors started falling in my lap. I missed good deals thought because people saw my thread and started short-stopping, and the people posting in my thread were posting elsewhere. If you get a good deal there snap it up right away. Work smarter, not harder, to find your parts!
Intercooler - $250 - $350 for eBay, $400 - 800 used, $500 - $1000 new.
I've decided on the Boost Factory SMIC for this project, because it will be efficient enough for the k04 (and still support a GT series turbo if I change my mind), while mounting in a stock location which will eliminate a need to hack my bumper, remove my fogs, and avoid any issues with the intercooler blocking airflow to my radiator or bouncing off the ends of a pothole in Boston and getting damaged. SMICs have show for be on equal ground with FMICs, and this is a great opportunity to demonstrate that.
If you want to go FMIC, and want to save money, the eBay DIY FMIC as discussed on another board seems to be a great route.
An upgraded intercooler is required for most more agressive files, so don't skip this.

click HERE to jump to more pics of the intercooler.
OE 225 TT MAF - $70 to $160 remanufactured, $150 - ?? new.
Audi Part number: 06A906461EX / Bosch part number 0 986 280 211 X - This part, for the AMU engine, has a 3" OD, and you should use the sensor AND housing. GIAC calls specifically for the OE 225TT piece, Unitronic says that most 3" OD hosings and sensors from Audi/VW should work. I think you'll be safe with a vr6 unit, which is supposedly cheaper, but I'm sticking with the TT unit on basic principle since either software company says it will work. MJM Autohaus sent me a part ending in MX, which is for, the BEA Engine, and they claim it is interchangable. We shall see.
Prices for this are ALL over the place. I'm heasitant to put any links in here because prices have changed TWICE since I began this thread. The two best prices I can find currently are at MJM Autohaus and German Auto Parts. Even if other places are cheaper GAP has some of the best customer service I have ever seen, and they are on top of their info (on par with DieselGeek, all around, if you've dealt with them you know!). MJM has been great as well, although in all honesty they seem a little more confused when you ask them questions. Can't go wrong ordering from either, as they are head and shoulders above most other places you're going to be able to source parts.
Software - $650
Even though I have Revo currently I've decided Unitronic is the way to go for this project. On paper they have a much more solid k04 program than GIAC's hammer file. They are able to remove the SAI, and make sure my test pipe does not throw codes, which GIAC does not seem to be able to offer me. Unitronic is confident that they can easily beat the 200whp provided by GIAC's hammer file, and I've heard a lot of good things about their software from tuners and users. It looks like nobody in here has tried this route, and the common conception is that GIAC Hammer file is the only way to go for the 01. Hopefully we will see in this thread that Unitronic is a fantastic alternative. If all goes well and the software lives up to expectations it will be the new standard. Only dyno time will show for sure though.
For more info, click here for GIAC's parts list for the Hammer file.
Some other bits and pieces:
SAI Removal - $45
twenty squared has a block off plate and resistor for this, I will be picking those up as well to get the dustbuster out from under my hood. One of the benefits on Unitronic is that they can code this puppy right out, so between the plate, the resistor, and the software codes from this are a thing of the past
MAP Relocation - Click here to jump to post
not as much a part as a few parts coming together. DBW cars have a MAP sensor on the Intercooler. If your FMIC/SMIC core doesn't have a bung welded to it, here's is a nice option that moves the MAP to a more accessable location.
Some parts I am not using:
ATP or Kinetic manifold - All the stuff I've read seems to say that these give you more top end but take a bit of your low end. Part of the reason I want the mild k04 upgrade is because the car lives and drives in the city. I'm not going to bomb down Comm Ave at 120. I do need to cross some intersections that would make you think twice about the existence of god, so I'll take the low end. IF of course someone wants to donate a manifold to prove the critics wrong, I will dyno before and after and allow you to use the charts.

Here is a car with a full K04 upgrade running on a dyno



Staff member
Someone's install

The K04 install..where to begin? After having serveal people doubt the turbo, saying it will leak and just end up blowing up, I listened to the people who accuallty understand the 1.8t. And no, thats not the 1.8t forum. The plan was to start in the morning and do a straight K03 to K04 swap. Should be done by dark, not excatly.

Where all the work took place.

I got a late start that day and we didnt really start tearing into the car until after 2 that afternoon. It looks easy enough, a couple bolts here and there and it should be golden. Not really. Took off the inlet with all that good stuff, things were going fine. No major hold ups. Looks like we are going to get this done by dark, as planned.
Intake off.

Inlet off.


Now getting the top oil and coolant lines isnt all that bad, expect the coolant flows everywhere without reason. Gives you a nice new scent along with a nice puddel to lay in. The cat to turbo bolts werent that bad, just the bottom one was a little tough.
Top oil and coolant off.

I lost about half my coolant. Not fun at all with this stuff everywhere.


The old k03, the thing was eating my oil like crazy. Glad to see it go, we had some good times together.

The next one was the turbo bracket, the bracket from hell. It was a bracket that bolts to the side of the turbo then wraps around under the turbo and attactes to the block. I believe it was a 6mm hex, 10 grade or whatever they call them. Meaning you have to crank on them until you break it loose, or strip the bolt into the a round piece of metal. We had the 2nd option chosen for us. After stracting our heads for a good time and trying various things like trying to pound a socket on it wasnt working. So we just say screw it bust out the dremmel tool and decide to cut it off. Well, the dremmel head breaks off and delays us big time. Under the turbo is the oil return line, blocked by the damn bracket. The bracket had to go.

Finally got the damn bracket out and finished getting the oil return line out. By that time darkness set in.

Time came to put the new turbo in. The oil return line under the turbo is the hardest part because 1. you cant see anything. 2. your under the car on your back. 3. your fighting gravity. Everything else is pretty much in reverse order. It wouldnt of been bad at all expect we couldnt see anything. But we managed to do with a flashlight and a little light from the laptop.

The rest of the stuff went back tonight nice, except the turbo inlet pipe. We couldnt get it to clamp right on the turbo. I think we were just tired and wanted to get done. So with everything else ghetto rigged up the car was ready to go. Started it up, no cel. Everything sounded good. No coolant light either, I was surprised by that. So thats it, right? Hur-ray!...Not really.
There was still the issue of me getting home, a good 40 mins away. And thats at 80 mph the whole way. So first the issue was going to get disstilled water to add to the coolant. Giant Eagle was open, so I headed over that way. Then I took off slow, didnt feel any different. I knew my intake cone was off because the sucking sound was way too loud. Went about 10 mph the whole way and parked it.

Went in and got my water. Went to check out and the cashier took one look at me and said ''Working on a car ..eh?'' I smiled. I dont think I said anything, I was too tired to move my lips open. Went outside and filled it up. So the coolant was good. Now I needed gas. Ran down the road to the gas station. Its packed. 2 in the morning and the gas station is packed. Theres a line a mile deep inside and every drunk from the bars is there getting a cold cut sandwich paying with crumbled dollar bills and loose change that they didnt tip the bartender with. Finally got out of that mess and made my way onto the turnpike. Didnt boost at all the whole way home. I maybe saw 3psi at one point in time. Everything ran really well.
I was starting to see the light.

Sooner or later I made it into town without any problems at all.

Now, with home in sight, It was time for a full out run up and down the road a few times. It was past 3 am so everything was good as far as other cars, police, ect.
Now, I pull out first gear and at first when you hit boost it feels like a regural chipped K03. But once you get close to 4000 rpm, it steps it up to another level and the car takes off. The front end lifts and its just another level than Ive ever seen on my K03. Second and third gear was kind of a let down, wasnt the same kind of experience that it was in 1st gear. But it still felt strong. Didnt get a chance to really test 4th and 5th because I'm over 80 when running out 1st through 3rd. I went home, let the car cool down for a good while, shut it off and went to bed.

Couple things I noticed about the install.
1. If you reallllly dont know your car or how it works. Dont try to do this by yourself. It may look like a straight swap, but its not as easy as it sounds. Not by a long shot.
2. You need another person to help you, I have no doubt in my mind that a single person cant do this job by theirself. Its just not possible. Too much stuff needs to be held in place and its just not going to happen if your flying solo on the job.
3. Make sure you have probably 50 bucks in your pocket ready to be spent. Because your going to need the money to go by random stuff like tools or a few odds and ends.
4. Plan ahead! If your going to do this, start about 8 a.m. or earlier. You'll save yourself from working in the dark later. I made the mistake of starting too late and it hurt me in the end.
Last but not least. Thanks to Mark and Val for helping me on the job. Especially Mark. I would of been up **** creek without them. So, in the end. Is it worth the upgrade? Yes, especially if your going to be using special fueling, fmic, 5 bar, all the good stuff. With all the bolt ones, you should have a solid 280 ft lb.


Staff member
Lot's of people have been talking abot K04's for the A4 so I thought I would post up info that I have found and post it up, I figured you might make it a sticky will try and find info for Bigger turbo's at some point.


Staff member
Not my Shizzle but I know where to find it.


Staff member
A bit more

[FONT=verdana, arial, geneva]A4 K04 turbo upgrade[/FONT]

[FONT=arial, geneva]In the never ending quest for more power I present to you... [/FONT]
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[FONT=arial, geneva]The K04-015 turbocharger[/FONT]
[FONT=arial, geneva]From the outside there is no visible difference between stock and the K04. I'm told it's what's on the inside that counts -- a more efficient turbine which allows higher air volume at the same boost pressure.[/FONT]​
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K03 cold turbine
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[FONT=arial, geneva]K04 cold turbine[/FONT]​

[FONT=arial, geneva]As you can see there is a difference between the turbines. I don't know much about turbo design but the K04 seems like it has a more aggressive blade pitch. Seems like it would take a bigger "slice" of air while rotating. Just a guess.[/FONT]
[FONT=arial, geneva]The K04 sounds distinctly different from the stock K03 unit. Any 1.8T owner who has been running a 0.8 or 1.0 bar chip and has a sharp ear would be able to tell something was up the first time you spooled up some boost. While the K03 has a "ffffweeeee" sound the K04 has a higher frequency "swsssss" sound. Even with the stock ECU you can hear the K04 at 7 lbs of boost. The K03 with a stock ECU is completely silent at 7 lbs. The K04 whistles like it means business... even at 5 psi. I find myself easing into the throttle just a little now and then to hear it spool... cool sound.[/FONT]​

[FONT=arial, geneva]The 235hp turbo kit I purchased included:[/FONT]​
  • [FONT=arial, geneva]K04 turbo[/FONT]​
  • [FONT=arial, geneva]all required gaskets, bolts and washers[/FONT]​
  • [FONT=arial, geneva]software [/FONT]​
  • [FONT=arial, geneva]air filter[/FONT]​
  • [FONT=arial, geneva]the vendor claims an exhaust is not required for 235hp[/FONT]​

[FONT=arial, geneva]I've also installed Bosch Silver F2CS spark plugs (purchased separately from elsewhere) which are a cooler heat range to help curb detonation.[/FONT]​

[FONT=arial, geneva]It's right... finally![/FONT]
[FONT=arial, geneva]If you've been following my K04 turbo installation saga you know I've had months and months of problems with the upgrade -- 4 months of problems to be exact. I had no end of trouble with the car.. it just wouldn't run correctly and performance was nowhere near the claimed horsepower. We just couldn't get the software right. The vendor kept their nose to the grindstone and eventually found the magic combination that makes my car purr... or should I say growl. [/FONT]
[FONT=arial, geneva]The 1.0 bar chip upgrade from stock is a much more dramatic improvement overall than a K04 upgrade. However, the K04 turned my car into feisty beast that charges hard as low as 2300 rpm and makes it presence known until 6,000+ rpm. Driving around town and on the freeway it slaughters most traffic with or without a downshift when you lean on the skinny right pedal. 4500+ performance is good and the power drop-off experienced after 5000 rpm with the K03 turbo and 1.0 bar chip is gone -- the car has a satisfying pull until you bump into the rev limiter. No increase in turbo lag with the K04. I like this setup it was just a long road to get to this point.[/FONT]​

[FONT=arial, geneva]But, if you had visions of showing your tail lights to that pesky ///M3 you see on the way to work every now and then you'll need just a little more out of the little 1.8T unless you catch the guy (or girl) gawking at themselves longingly in the mirror, the M3 is equipped with a slushbox (a sin for sure... they deserve to get dusted) or the other driver is just not on the ball. My car is fast but it's not quite into the ///M3 neighborhood.[/FONT]
[FONT=arial, geneva]Comments from Steve Brown:[/FONT]​

[FONT=arial, geneva]Well, Don came over on Saturday & was brave enough to let me drive his car (my last three vehicles were autos & my manual experience comes from my fathers TR4A & his MGA (no syncros to get back to first!). Anyway, I'll let him tell the tale of how he got the car to where it is now, but I'll tell you, his car is now (1) fast, (2) stable, engine wise, throughout the rev range, (3) fast, (4) fun, (5) fast. [/FONT][FONT=arial, geneva]The car gets up and moves! (He might try to say there is a bit of hesitation as you spool up the turbo off the line, but it's MINOR). Cruising at anywhere from 25-60 (no place for HIGH speed test), you could basically aim the car & GO, RIGHT NOW![/FONT]​

[FONT=arial, geneva]My humblest apologies to Don's clutch, getting moving & 1-2 were VASTLY different from a 75hp 30 year old car. [/FONT]

[FONT=arial, geneva]Wow...I realize now two things: (1) The 1.8T is an amazing piece of work, (2) I'd be completely in debt modifying one if I had it.[/FONT]​

[FONT=arial, geneva]There is a turbo whistle, but I only noticed it when I was outside the car. The car sounds like a MACHINE, but not at all offensive (still stock exhaust). [/FONT]

[FONT=arial, geneva]A consolation: My horns are WAAAAAY louder than his. [/FONT]​

[FONT=arial, geneva]Donp: [That's for damn sure... I was shocked! Really loud! I need these!!][/FONT]​

[FONT=arial, geneva]Steve[/FONT]​

[FONT=arial, geneva]98.5 2.8[/FONT]

[FONT=arial, geneva]Testing I've done so far has resulted in 1/4 mile times of 14.61@93.30 mph and 0-60 runs of around 6.01 seconds. These were the first runs I'd done with this configuration -- I suspect I can shave a tenth or two off of these times once I learn the powerband of the car and where to shift to squeeze out the most performance. If so, that would put me in the high 14.40s or 14.50s. That aint bad for a 3600 lb car with a 1.8 liter engine. I have not had time to do in-gear testing yet but I suspect those times will be good too. Yes my friends I've now got a sleeper -- A mild mannered looking A4 with a split personality. My goal has been accomplished.[/FONT]
[FONT=arial, geneva]Update: Since my initial 14.61 1/4 mile run I've done additional runs. My best time so far: 14.49@95 mph.[/FONT]
[FONT=arial, geneva]I did find that the car runs perfectly with the stock (ie. factory) prom installed. I wanted to verify I could run the stock software as I heard that the car would not run correctly with a K04 -- mine does just fine. Smooth (albeit slow) factory power right up the the rev limiter.[/FONT]​

[FONT=arial, geneva]The Bottom Line[/FONT]
[FONT=arial, geneva]Do I consider the upgrade worth it? Would I do it again? Yes and yes. Although, I don't think I'd be so patient the next time.[/FONT]
[FONT=arial, geneva]If you are one to expect an upgrade to be truly an install, drive and forget ordeal I suggest you do your homework before you take the plunge on an upgrade of this type. I've done heavy duty engine upgrades and such before and they always have a few rough spots... it's just the nature of high performance.... this one was no different.[/FONT]
[FONT=arial, geneva]Here's some interesting (and somewhat puzzling) information based on published dyno data for stock, chipped and chipped with a K04 turbo. The puzzling part is the stock dyno pulls indicate the engine was performing above the factory claimed horsepower and torque. Was this engine really performing above average or do we have dyno error or some other influencing factor. Personally, I adjust the numbers based on what stock should be knock off a few HP and LB-FT as some kind of crude normalization -- I suspect would be reality numbers. Note that this data was "eyeballed" off of pictures of graphs so this data is probably not entirely accurate. Repeat: Assume these numbers are very crude (and potentially inaccurate) data. I don't want any email telling me my numbers are bogus or misleading... I worked with what was available just to get a ballpark idea. You might say bad data is worse than no data at all... probably true... but since I did the work for my own curiosity I figured some others might care to see the info too.[/FONT]​

[FONT=arial, geneva]Dyno Data[/FONT]

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[FONT=arial, geneva]


Staff member
Just a little more

K04-015 Turbo Installation

I originally planned to have detailed, step-by-step installation instructions for the turbo. But, after doing the install myself I came to the conclusion that if somebody needed detailed nut-by-nut, bolt-by-bolt, part-by-part instructions to do the install they probably should not be doing it. There are way too many steps to lay them all out in a straight line and document. Robert Bentley Inc. may do it... but I'm not Bentley. IMO, if the thought crossed your mind or you have to ask, "Can I do the install myself?" the answer is probably "No". I'm not suggesting the install is hard -- it isn't. It's pretty straight forward and really doesn't have any big "gotchas" along the way but it does require a certain amount of mechanical ability and a reasonable complement of tools to do the job. I would think nothing of yanking a transmission in my garage on a saturday morning to replace an input shaft seal... would you?​


The Tools
(Note the band-aids... flesh sacrifice to the wrench gods ensures success)
I took 4:15 to complete the job. 25 minutes of that time was spent looking for one stupid bolt that I dropped (the gods snickered). I also spent time taking pictures and comforting my 7 month old Golden Retriever who was none to happy with the noise of my air ratchet and the air compressor suddenly springing to life... off into the house with him after a romp in the back yard to chill him out. Oh yeah, I ate an unfrosted blueberry pop-tart too.​

So, what I decided to do is skim the surface, hit the high points if you will. The nitty-gritty details are up to you and your ability. There are a few things worth noting along the way and I'll cover that kind of information.​
  • You'll need to put the car up on stands or on ramps for access from below.​
  • You do not need to drop the exhaust.​
  • Plan on an oil change. The turbo oil drain line connects to the bottom of the oil pan so the current slippery stuff is history unless you catch it and <gasp> put it back in. You wouldn't do that... would you?!? I didn't think so...​
  • If you're careful you'll only loose a couple ounces of engine coolant.​
  • Obviously, you need to remove the belly pan.​

[FONT=arial, geneva]Removing the engine cover first requires undoing the snaps at the front and rear.[/FONT]​

[FONT=arial, geneva]Then, if you have a car with the 2-piece engine cover, pull up on the rear section to free the small cover then slide it forward to get the cover finger out of the cover slot. At this point lift the main cover from the snap side and it will "hinge" off the mounting tabs. [/FONT]

[FONT=arial, geneva]You must remove the air box for access to the turbo. Remove the airbox cover, the one bolt that secures the airbox, 3 hoses, the cold-air intake snorkel (secured near the radiator), the turbo inlet hose on the airbox side and the one electrical connector that leads toward the front to the boost control solenoid. Push down on the spring wire on the connector to release it. Audi chooses to use one-time crimp type clamps on the hoses so pick up some clamps. Note that the heat shield remains attached to the airbox. The airbox will just flop up onto the cowl once disconnected although still tethered to the car by hoses and wiring.[/FONT]

  • [FONT=arial, geneva]Remove the heat shield (2 bolts, 3 screws) [/FONT]​
  • [FONT=arial, geneva]Later disconnect the coolant and oil supply lines. Pinch the hose of the coolant line before removing. You'll want to do the lines later I just mention it here cuz the picture is convenient. [/FONT]​

[FONT=arial, geneva]On the floor with ya. Drain the oil and loosen the oil drain line. While you're down there loosen the clamp for the turbo inlet hose. If you are double jointed pull the hose off... if not go back upstairs and disconnect the hose.[/FONT]​

  • [FONT=arial, geneva]Remove the turbo mount bolt. [/FONT]​
  • [FONT=arial, geneva]Note that there is a plug and the bolt. Remove the bolt, not the plug.[/FONT]​

[FONT=arial, geneva]The bolt is a 6mm allen head. If your 6mm is looking a bit ragged I strongly suggest you get a fresh one before starting. This bolt was extremely tight and will strip easily with a worn wrench. No, I didn't strip it. The bracket remains on the engine for the duration of the install. Now is a good time to remove the oil coolant supply lines (19mm & 17mm) with the exception of the banjo line. Ignore it for now. [/FONT]
[FONT=arial, geneva]Loosen the turbo to cat bolts. The bottom bolt is easier to access from underneath if you have a looooong extension and reach in from behind toward the front. Do the 3 exhaust manifold to turbo bolts too.[/FONT]​

[FONT=arial, geneva]At this point wiggle the turbo forward to gain access to the banjo nut for the coolant return.(watch the oil return line -- it likes to hang on part of the body down below) Watch those banjo washers... then loosen the coolant line mounting bolt (10mm) between the wastegate servo and the cold side turbo housing. Back under the car, remove the oil return line from the turbo. (2 allen head bolts) [/FONT]

[FONT=arial, geneva]Survey for anything attached that shouldn't be... Wiggle the turbo out.[/FONT]
[FONT=arial, geneva]Over on your bench, install the turbo to cat studs in the new turbo and transfer the oil and coolant line fittings. I chose to prelube the turbo bearing. I just dipped a straw in some oil, put my finger over the end of the straw to hold the oil, and then filled the oil passage. Make sure you put oil in the oil hole and not the coolant hole. Oil feed is the bottom hole. The thought of starting the car with a dry bearing just makes me queasy. [/FONT]
[FONT=arial, geneva]Ok, now just throw yourself into reverse and put it all back together.[/FONT]​

[FONT=arial, geneva]Oh, don't forget to install the upgraded software... after you've washed your hands of course.[/FONT]

[FONT=arial, geneva]Take a look at the cool looking belly pan. Air ducts and all.[/FONT]​

[FONT=arial, geneva]Points to note:[/FONT]
  • [FONT=arial, geneva]Be sure to put in the turbo mount bolt before you snug up on the exhaust manifold to turbo bolts.[/FONT]​
  • [FONT=arial, geneva]The banjo nut washers, technically, should not be reused. My kit didn't come with them and it was too late for me to get replacements. Call me anal.[/FONT]​
  • [FONT=arial, geneva]Have fun with the oil return line on the turbo end... it was a pain to put back on for some stupid reason. The line also likes to wedge on part of the body down below while your scooting the turbo back into position. If things won't move $5 says the line is wedged below.[/FONT]​
  • [FONT=arial, geneva]Take care not to overtighten the oil and coolant supply lines. They are compression-type fittings and don't need much more than "snug".[/FONT]​
  • [FONT=arial, geneva]Fill 'er up with fresh oil.[/FONT]​
  • [FONT=arial, geneva]When you're all done start the car and let it idle until it's up to temperature... check for oil, coolant, and exhaust leaks.[/FONT]​


Registered User
Pretty good suff posted here.:thumbsup:

I am trying to piece together a K04 kit for my B5 ANB for quite some time already. There is no problem for gathering the hardware parts, but nobody was to be able to sell me a software for my ECU (4B0906018K). I contacted GIAC and some other US based software companies, but all their answers were negative - they had files only for US marketed AEB, ATW and AWM. It is acommon problem for me and few guys from local forums.

Do you happen to now a company that sells a K04 file for European marketed B5s?


Staff member
You would have to get a custom map done just post up in the main section someone will point you in the right direction.

Samuel c5 Q

Registered User
VCDS Map User
Silver Supporter
Did you measure your wheel sizes at all of the k04-015 turbo. I finally measured a k04-023 I got and was surprised to find it didn't match internet information. The compressor wheel is what the usual is at inducer 42mm and exducer of 56mm. The turbine however matches the sizes stated for a k04-015 turbine wheel of inducer 50mm and exducer of 42mm.


"Stick a V8 in it!"
Staff member
VCDS Map User
50/42 is correct for a K04-02x turbine.

the k04-015 is smaller, something like 46/42.

The -015 is a fairly pointless turbo, you might as well just use the K03-073 from the 190ps B6, as its essentially the same thing.

Samuel c5 Q

Registered User
VCDS Map User
Silver Supporter
Thank you. I was hoping they were the same size and I could buy a turbine housing to mate to my manifold. I read of someone modifying a k04-023 to fit to a longitudinal engine so will have to find that post again and check what it was that he done to make it fit. The tt or s3 exhaust manifold would be the simplest thing but don't believe it would fit and would foul on the chassis leg /air box. OP, sorry for hijacking your thread a bit.


"Stick a V8 in it!"
Staff member
VCDS Map User
A3 or S3 manifolds mount the turbo the other way round, and would have the exhaust pointing towards the radiator.

Oranoco was running a K04-02x turbo, but it had a machined standard K03 A4 turbine housing fitted to it.

Samuel c5 Q

Registered User
VCDS Map User
Silver Supporter
I have the same thing a k03 machined to take a k04 turbine wheel but was hoping to use a k04 housing. I'll look for a solution. Thanks again.