K03 part numbers

[vwmk3jon]

need a new turbo as im pretty sure mines now goosed after it was rebuilt (not by me i may add) and now only boosts at 0.5bar

anyway... i see turbos listed as K03-*** with three numbers. what do these mean and which is best?

cheers

[Andy]

From memory:

K03-005 - the most common 150bhp 1.8l 20v turbo from a Passat or A4.
K03-029 - turbine side is larger than above, so boost threshold is higher but flows better at higher rpm than a -005.
K03-073 - from a 190bhp A4, is a -029 turbo with a larger compressor. Kind of a 'K03s' for the longitudinal engines.

With the 268° turbo cam I think the common K03-005 is a great all rounder. The -029 is handy if you're happy to sacrifice a touch of responsiveness for a few more bhp and I quite liked it. The -073 is what I run now, biggest issue I have is getting the Forge actuator to control boost properly at 21psi without creep.

[vwmk3jon]

Thanks Andy

mines not boosting at all well now. still sits at 0.5bar boost and sounds as tho its loosing boost (leak) somewhere but ive checked the pipes ive removed and theyre all tight as hell so im putting it down to the turbo being royally fubared.

[GR40]

Did u check the small pipe under the black plastic tube leading to the idle valve? I once forgot to put a clamp on that and the car would stay exactly at 0,5bar no matter the rpm. I could hear it hissing from inside the cabin and took me a while to figure out where the leak was cause it was under the manifold where I couldn't reach or see!