For the past month I've been split between either getting a new K03 or doing a K04 conversion (injectors, intake, sports cat downpipe) so i'd like y'all's opinion.
Long story short, my stage1 K03 is dying because it's constantly underboosting by 0.3-0.4bars. It peaks at 1.4 bars then drops down to 1.1 almost instantly. My mechanic (and tuner) thinks that it's 90% the turbo failing because almost every K03 he's worked with was either cracked internally or had a failing wastegate. We've smoke tested the engine and there are no leaks. DV is new.
Right now the car is stage 1 and it's supposed to push 270-275bhp but realistically speaking I don't think the turbo in it's current state can push more than 230-240.
Mods are as follows:
- R8 coils
- NGK BKR7EIX plugs
- Sachs X-tend OEM replacement clutch and DMF supposed to hold 430nm of torque
Compared to stock, the car is super responsive and allows me to snap around in traffic. When merging, I can floor it and it'll get up to speed fast and kick me back into the chair, which I love. Basically you see a gap, you take a gap. What the car lacks is power in the upper powerband or when trying to overtake on open roads past 100kph. It still pulls better than my stage 3 1.4 Jetta but I feel like I'm starting to want more.
Now as for the K04, would I be sacrificing this snappy responsiveness between 2k and 4k rpm for top end power? or would I retain the same low-down kick that the K03 can deliver to zip around town?
For the K04 conversion I'd go with upgraded injectors, rail pressure valve, sensor and map sensor along with a 200cell cat and an intake. I'm not very keen on a full sports exhaust because I quite enjoy how quiet the car is and would like to keep it that way. I think I've had enough of sports exhaust by driving the 1.4 for 4 years.
All thoughts and opinions regarding the K04 swap are welcome
Below are some graphs of my boost issue with wastegate duty cycle at 95%. Red is requested, green is actual boost.