K04 Turbo Exhaust Turbines and Compressor Wheels

[AudiAR01]

So I have built my own k04 turbos. Using BW turbine housings, Turbo Rebuilders UK Enhanced CHRA's, and Knock off compressor housings. I have standard 4+4 comp wheel it's just billet over the standard cast wheel. But I have seen other comp wheels with a different amount of blades. And the standard turbine wheel is a 12 blade. But they make an 11 blade and 9 blade turbine wheel. Supposedly the 9 blade causes less back pressure over the standard 12 blade by allowing more exhaust to pass through relatively faster. And spools more in the upper RPM range. And the 12, blade spools up faster but doesn't provide as much boost in the top end. I know the smaller A/R doesn't help with the k04 running out of breath in the upper RPM range. They are good for the bottom end quick spool. Has anyone have any definitive information on the difference between the 9 blade and 12 blade turbine wheel. And or the difference in the 4+4 comp wheel and the 11 blade billet wheel. I'm thinking about possibly changing over to a 9 blade turbine wheel and the 11 blade comp wheel over the 12 blade ET and 4+4 comp wheel.

2003 A6 2.7T 6spd Stage 1+ (motor pulled for stage 3+ upgrades)

2001 Allroad TIP Stage 1
2006 A3 2.0T 6spd Stage 1

[AudiAR01]

I'm debating on having my spare k04-025 and 026 turbos machined out to accept a bigger turbine/ and or complete 064 Chra inserted. Factory turbine size is 42/50mm and with 40/51mm compressor side.

K04-025/k04-026
Turbine
42/50
Compressor
40/51

K04-028/k04-029
Turbine
44.5/50
Compressor
41.9/56
Shaft
7.0-turbine side/4.6-comp side

K04-064
Turbine
44.5/50
Compressor
46.38/55.94

The 064 turbo compressor exducer side is bigger than the rs6 k04-028/029 turbo.

Has anyone tried machining their k04s out to accept the larger 064 comp wheel. You can definitely take a k04-025/026 turbo and machine them out to rs6 specifications. I believe there is still enough room to go out to the 064 comp wheel. So my plan is to take my extra Chinese comp housing and exhaust turbine housing and try to stuff the 064 Chra into it. To use the 064 comp wheel. And have twin 064 turbos on the 2.7t or Biturbos to be correct. They all 3 use the same size shafts. On both turbine and comp sides.


Thoughts????

Something different than bi k03, k04s both rs4 and rs6 upgrades. Or TTE, TC, frankenturbos, ECT ECT. Are the options we have now. Why not another option. You could even machine rs6 comp housings to the larger 064 comp wheel if this works out.

2003 A6 2.7T 6spd Stage 1+ (motor pulled for stage 3+ upgrades)

2001 Allroad TIP Stage 1
2006 A3 2.0T 6spd Stage 1

[Stock B6]

Dead thread, I know, but I was literally just thinking about this and found this thread. I have no idea why nobody else is interested in this, would be a fairly cheap and reliable upgrade path, capable of well over 600whp.

AR01, did you figure anything out in machining the comp housing?

[AudiAR01]

Sry got a new phone and didn't re-download the Audizine app. I ended up just staying with the comp wheels and turbine wheels that came with chras from turborebuildersuk

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[FrankD400]

I looked into this a lot a few years ago, you know anyone that can machine the housings for the CHRA from the 0064? Probably not enough meat in the 025/026, but the RS6 turbos should be able to do it.

[shoguncito]

it is possible, i have a 064 stufed inside mu k03 029, lots of work but i made it work, cannot go bigger turbine, as i tried a mazdaspeed one and cut through, guess that is how you find out, but as far as compressors go 50 probably 51 mm is the biggest you could fit

[AudiAR01]

it is possible, i have a 064 stufed inside mu k03 029, lots of work but i made it work, cannot go bigger turbine, as i tried a mazdaspeed one and cut through, guess that is how you find out, but as far as compressors go 50 probably 51 mm is the biggest you could fit

How's the spool with 064? Probably be better in a k04 housing than a k03. But awesome that you stuffed a 064 in a k03 housing.

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[Sjjarvis92]

I'm planning on doing a project like this as well with the goal to bridge the options between the typical RS6 Hybrid turbos that we have now and get closer options to TTE780s or higher without having to spend $4000. Planning on buying some of the cheap replacement K04-028/29 and or the K04-025/26 turbos off ebay to start the project. It seems to be the easiest way to get cores for the comp and turbine housing. plus a chra to rebuild with good parts, ebay turbos are sub $600.