K03 to k04 swap on Jetta 1.8T questions?

01 Jetta 1.8T Manual and completely stock.

Planning on changing out my stock turbo since its been over 140,xxx miles on my Jetta, and I also plan on doing more small upgrades in the future as well. Right now for the FIRST upgrade, I want to go just slightly a little bit bigger turbo than the stock k03. But before I even start buying stuff, I have a few questions I would like to ask all the VW tuners out there. I did do some research with, vwvortex and other vw fourums, but seems like nobody giving me a solid confirm answer. So I would like to try yahoo. Anyways, my questions are:

1. Is it a direct fit?

2. Will CEL comes on?

3. Do I need a software/file, or is not necessary?

4. Will the k04 turbo works with a stock motor?

5. Are there any difference between k03 and k03 S ?

Thank you.

2 Answers

  • 8 years ago
    Favorite Answer

    1. There are many variants of the k04 turbo, some are designed for longitudinal motors, some are designed for transverse-mounted motors like the one in your car. You will most likely be looking for a k04-020 or a k04-001 if you wish to use your stock exhaust manifold and downpipe.

    2. It won't come on as long as everything is installed and configured correctly.

    3. You can run on the stock file, but there will be no benefit to the larger turbo, and you may have some driveability issues arise from turbo surging.

    4. An aggressive k04 tune on race gas or E-85 ethanol is capable of generating enough torque to bend the stock connecting rods, but as long as you run pump gas you shouldn't have any problems with the stock motor.

    5. The k03s is a slightly larger version of the k03 that VW began using during the 2001 model year. In 2002 VW raised the factory boost pressure on the k03s from 8 PSI to 12 PSI and started realizing some of its potential.

    I would recommend you going with a k04 kit so that you aren't worrying about getting properly paired hardware and software. As an alternative, and what I am currently running on my 2002 GTI race car, you can get something called a k04 hybrid turbo kit, which will make more power and typically costs less. Check out frankenturbo and gonzotuning for two of the most popular hybrid kits.

    Source(s): VW tech and enthusiast
  • 4 years ago

    K04 Vs K03

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