Well looks like the vdub guys are jealous

[DSMConvert]

Ran into a 1.8t bringin the new 6 back from the dealership this afternoon at the gas station and after about 10 minutes of talking, turns out our stock k04 turbo is a fairly big upgrade for them...Talked for a little while longer and he gave me some sites that actually sell stuff for the k04. From what he told me this turbo also came stock on the rs4 version....just thought I'd share this if anyone is looking for parts, upgrades, or what to do with theirs when they upgrade...

On that note I haven't looked too much into it yet, so I'm not sure as to the actual housing similarities/differences and such...the kid was going to give me a call tomorrow to meet up with his buddy who had the k04 upgrade to compare to...

 

[buit9110]

wow, rs4...I didn't know that.

 

[CitizenPro]

Thats always good to know Nice info

 

[DSMConvert]

talked to the guy today with the "upgraded" k04 on his 1.8t...says the turbo is good till about 18psi(as was previously speculated on here). Hes going to check to see the trim and what not is on his to see if it is indeed the same cartridge...he pointed me to a few websites to get more info...

 

[avarela86]

They also like to go with a GT28RS, or so I was told by a buddy of mine that has an R32. He used to have a 1.8T on like 22 PSI or something and always wanted my turbo. Then he went with the beauty of VW....I love those R32.

 

[ssinstaller]

talked to the guy today with the "upgraded" k04 on his 1.8t...says the turbo is good till about 18psi(as was previously speculated on here). Hes going to check to see the trim and what not is on his to see if it is indeed the same cartridge...he pointed me to a few websites to get more info...

It might hold 18psi on that 1.8L, it wont hold that on our 2.3L...

 

[DSMConvert]

eh you can't reallly make that comparasion without knowing other factors...there are way too many factors to make a flat line association like that...remember holding boost is more than just engine displacement and cfm, it also must take into account backpressure/ect... so if the 2.3 has an exhaust flow restriction of 23% and the 1.8 has an exhaust restriction of 23% then the boost levels would be comparable(not necessarily equal)...however if the 1.8 had a freer flowing exhaust setup then there would be no way to compare the ratings based solely on engine displacement... When I say good for 18psi I mean the efficiency rating which is done on a flow bench not a particular car application...

Edit: Changed for misleading statements and clarification. This was to address ssinister's below comments...

 

[ssinstaller]

eh you can't reallly make that comparasion without knowing other factors...if their exhaust is restrictive on the same scale as a 1.8 vs a 2.3 then yes it would...there are way too many factors to make a flat line association like that...remember holding boost is a function of backpressure and cfm NOT engine displacement... so if the 2.3 has an exhaust flow restriction of 23% and the 1.8 has an exhaust restriction of 23% then the boost levels would be comparable...however if the 1.8 had a freer flowing exhaust setup then there would be no way to compare the ratings... When I say good for 18psi I mean the efficiency rating which is done on a flow bench not a particular car application...

How can you say boost is a function of backpressure and CFM, but not displacemnt, when displacement is a part of the equation to determine CFM??

ACTUAL compressor map for a K04 turbo.

Pressure ratio is calclulated by Absolute pressure/Atmospheric Pressure or 15.7 PSI+ 14.7 PSI/14.7 PSI
CFM need is...
CFM = (L x RPM x VE x Pr)/5660
CFM= (2.3 x 6500 x 90 x 2.068)/ 5660
CFM= 491.6
This is the minimum the turbo must flow with an engine with a 90% VE to HOLD 15.7 PSI to 6500 RPM.
As you can see at a pressure ratio of 2.068 the turbo is RIGHT on the edge of its efficency.
The MAXIMUM this turbo can flow at a pressure ratio of 2.068 is at the right hand upper edge of the map. Which just happens to be... 0.175 cubic meters a second. This converts to around 371 CFM.
Now we have already calculated the CFM needed to hold 15.7 PSI to redline. Thats 491.6 CFM at a 90% VE. This converts to 0.2320 cubic meters a second. This happens to be COMPLETELY off the chart and unattinable for this particular turbo.
This turbo is Maxed Out. It is pretty close to being maxed out from the factory...
This is why the ECM drops boost in the upper RPM band--to protect the turbo. Unless Mazda is using a different version of the K04, it will NEVER efficently support 15.7 PSI at 6500 RPM.

 

[Hambino]

Yeah, VW/AUDI guys love swapping the K03 to the K04, not to long ago a friend of mine swapped out his K03's on his B5 S4 for custom K04's with clipped wheels. Great turbo to have when you have two of them, however, just the one might merit a swap to a GT-series.

 

[dread]

How can you say boost is a function of backpressure and CFM, but not displacemnt, when displacement is a part of the equation to determine CFM??

ACTUAL compressor map for a K04 turbo.

Pressure ratio is calclulated by Absolute pressure/Atmospheric Pressure or 15.7 PSI+ 14.7 PSI/14.7 PSI
CFM need is...
CFM = (L x RPM x VE x Pr)/5660
CFM= (2.3 x 6500 x 90 x 2.068)/ 5660
CFM= 491.6
This is the minimum the turbo must flow with an engine with a 90% VE to HOLD 15.7 PSI to 6500 RPM.
As you can see at a pressure ratio of 2.068 the turbo is RIGHT on the edge of its efficency.
The MAXIMUM this turbo can flow at a pressure ratio of 2.068 is at the right hand upper edge of the map. Which just happens to be... 0.175 cubic meters a second. This converts to around 371 CFM.
Now we have already calculated the CFM needed to hold 15.7 PSI to redline. Thats 491.6 CFM at a 90% VE. This converts to 0.2320 cubic meters a second. This happens to be COMPLETELY off the chart and unattinable for this particular turbo.
This turbo is Maxed Out. It is pretty close to being maxed out from the factory...
This is why the ECM drops boost in the upper RPM band--to protect the turbo. Unless Mazda is using a different version of the K04, it will NEVER efficently support 15.7 PSI at 6500 RPM.

wow that is an excellent explanation of that chart I keep seeing and don't understand.

 

[DSMConvert]

Ssinister, I think you're missing my point. While I agree that it may not be in eff range on our 2.3, that wasn't the point I was tayloring to. Notice that I didn't say you were wrong. All I was trying to point out is you simply can't compare 2 different engines based on displacement and find when a turbo will bog out. As I mentioned there are several other factors to consider. I will edit my post, as I see it is misleading. What I meant was that when comparing 2 engines there are several more important factors to consider besides displacement(in the case where the difference is less than .8 liters). But the arguement is moot anyways, b/c according to the information I was given last night the turbo on the vw upgrade is not the exact same as ours, in particular it has a fairly different trim than the trim specs I've found for the mazda version. I'm assuming that the chart you have is for the "regular" k04 the vws use...I sent atp an email but I haven't heard back yet, as they seem to have a ton of exp with the k04. Whoops forgot the k04 info. Apparently there are several different versions of the k04 floating around. This gentlement said that teh vws use either a k04-15 or a -25 setup.