What is the (mechanical) reason for turbos to blow and why are K04s different?

S4Ca$hwhore · 10-08-2006, 10:18 PM

Imolavirus@BuehnEngineering · 10-08-2006, 10:25 PM

stock K03's usually blow because of the following reasons:
-increased oil temps due to the not so great oil feed line on the passenger side running very close to the exhaust manifold
-overspeed causing a fin to burst on the turbine wheel, this will then cause out of balance, premature bearing wear, ect...
-hot shut downs, not warming them up before WOT, ect...

The larger compressor wheel is the main reason for the K04's higher reliability. This leads to less oil starvation issues at extreme shaft speeds, lower heat, and higher efficiency on of the compressor wheel.

Justin:NorCal · 10-08-2006, 10:27 PM

from what I have been told the shaft speed often can have the finger pointed in it's direction. Now first understand that turbos are consumables. At some point, regardless of what you have given their nature they will not last forever. Anyway, the KO3 have a smaller compressor shaft than a KO4. The result is higher shaft RPM's. These can exceed 200k rpms!!!! Chipping obviously increases this shaft speed. The KO4 has a larger shaft, thus reducing the overall speed the shaft spins. Creating less strain.

2000SForce.free · 10-08-2006, 10:28 PM

Imolavirus@BuehnEngineering · 10-08-2006, 10:29 PM

the compressor wheel is what is going to be the main determinant of shaft rpm, but you're correct in the effect that shaft rpm can have.

UberVier · 10-08-2006, 10:32 PM

Imolavirus@BuehnEngineering · 10-08-2006, 10:36 PM

S4Ca$hwhore · 10-08-2006, 10:40 PM

ubalanced. Does that mean that zero clearance turbines have a higher chance of getting butchered? Maybe it doens have anything to do with clearnace, its just closer to the housing so a slight deviation would be a problem I imagine.

What do you think?

Mike2kS4 · 10-08-2006, 10:43 PM

Imolavirus@BuehnEngineering · 10-08-2006, 10:44 PM

so if something does happen the coating will wear off instead of causing damage to the wheel or housing. BUT, unless there is some reason for premature bearing wear, then the wheel is not going to wear the coating anymore past the initail break in.

We, including myself, have taken z/c turbos apart after 50K+ miles and there has been no wear beyond the initial wear of break in.

10-08-2006, 10:18 PM	#1
S4Ca$hwhore AudiWorld Senior Member Garage is empty, add now Join Date: Nov 2005 Posts: 1,056	What is the (mechanical) reason for turbos to blow and why are K04s different? __________________

10-08-2006, 10:25 PM	#2
Imolavirus@BuehnEngineering AudiWorld Super User Garage is empty, add now Join Date: Mar 2002 Posts: 17,943	they can "blow" for various reasons..... stock K03's usually blow because of the following reasons: -increased oil temps due to the not so great oil feed line on the passenger side running very close to the exhaust manifold -overspeed causing a fin to burst on the turbine wheel, this will then cause out of balance, premature bearing wear, ect... -hot shut downs, not warming them up before WOT, ect... The larger compressor wheel is the main reason for the K04's higher reliability. This leads to less oil starvation issues at extreme shaft speeds, lower heat, and higher efficiency on of the compressor wheel. __________________ -Jacob ^^^CLICK SIG FOR BUEHN ENGINEERING WEBSITE^^^ <big><big>Website Here!!!</big></big> <big>Items For Sale</big>

10-08-2006, 10:27 PM	#3
Justin:NorCal AudiWorld Senior Member Garage is empty, add now Join Date: Oct 2004 Posts: 630	My understanding... from what I have been told the shaft speed often can have the finger pointed in it's direction. Now first understand that turbos are consumables. At some point, regardless of what you have given their nature they will not last forever. Anyway, the KO3 have a smaller compressor shaft than a KO4. The result is higher shaft RPM's. These can exceed 200k rpms!!!! Chipping obviously increases this shaft speed. The KO4 has a larger shaft, thus reducing the overall speed the shaft spins. Creating less strain. __________________ 2000 Audi S4 Silver (stock) 2000 Audi S4 Stage 3 Black (Tip) Company Car - GT820 Nissan GTR

10-08-2006, 10:28 PM	#4
2000SForce.free Junior Member Garage is empty, add now Join Date: Jun 2006 Posts: 898	because bigger is better and what V V V said __________________ __________________________________________________ __________________________ 2000SFORCE'S MODS __________________________________________________ __________________________ __________________________________________________ __________________________ Race car driving is like sex, every man thinks they are great at it until they are with a pro. -Jay Leno

10-08-2006, 10:29 PM	#5
Imolavirus@BuehnEngineering AudiWorld Super User Garage is empty, add now Join Date: Mar 2002 Posts: 17,943	shaft sizes are exactly the same between the S4 K03 and K04..... the compressor wheel is what is going to be the main determinant of shaft rpm, but you're correct in the effect that shaft rpm can have. __________________ -Jacob ^^^CLICK SIG FOR BUEHN ENGINEERING WEBSITE^^^ <big><big>Website Here!!!</big></big> <big>Items For Sale</big>

10-08-2006, 10:32 PM	#6
UberVier AudiWorld Super User Garage is empty, add now Join Date: Mar 2001 Posts: 22,223	which is why I now have a self-imposed rev limit of 6k at WOT.

10-08-2006, 10:36 PM	#7
Imolavirus@BuehnEngineering AudiWorld Super User Garage is empty, add now Join Date: Mar 2002 Posts: 17,943	that will help......as shaft rpms start to rise very quickly the closer you get to redline __________________ -Jacob ^^^CLICK SIG FOR BUEHN ENGINEERING WEBSITE^^^ <big><big>Website Here!!!</big></big> <big>Items For Sale</big>

10-08-2006, 10:40 PM	#8
S4Ca$hwhore AudiWorld Senior Member Garage is empty, add now Join Date: Nov 2005 Posts: 1,056	Thanks, i was alwyas surprised to see those things chewed up and didnt see how they would get ubalanced. Does that mean that zero clearance turbines have a higher chance of getting butchered? Maybe it doens have anything to do with clearnace, its just closer to the housing so a slight deviation would be a problem I imagine. What do you think? __________________

10-08-2006, 10:43 PM	#9
Mike2kS4 AudiWorld Super User Garage is empty, add now Join Date: Jun 2002 Posts: 12,096	2nd. __________________ 2002 S4 Avant, 6spd. Bone stock. <a href="http://www.autospeed.us"> </a> Caveat: Any advice I express regarding potential tuning and such is purely informational. If your knowledge and abilities are not up to the task, no amount of advice can assist.

10-08-2006, 10:44 PM	#10
Imolavirus@BuehnEngineering AudiWorld Super User Garage is empty, add now Join Date: Mar 2002 Posts: 17,943	For zero clearance the coating we use is an abratable one...... so if something does happen the coating will wear off instead of causing damage to the wheel or housing. BUT, unless there is some reason for premature bearing wear, then the wheel is not going to wear the coating anymore past the initail break in. We, including myself, have taken z/c turbos apart after 50K+ miles and there has been no wear beyond the initial wear of break in. __________________ -Jacob ^^^CLICK SIG FOR BUEHN ENGINEERING WEBSITE^^^ <big><big>Website Here!!!</big></big> <big>Items For Sale</big>

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