RS2 Turbo - Naked!

[twoqu]

Here is a closer shot of the shafts. You can see the slight differences. If you look closely you can see the lefthanded thread of the RS2 against the righthanded thread of the ordinary K26. The RS2 slopes from left to right, the K26 slopes from right to left.
Notice how the RS2 is undercut. Another point is that the RS2 has I believe an M7 thread whilst the ordinary K26 has an M6 thread. The shaft dimensions appear to be the same.

[twoqu]

This shot shows a comparsion between the back of the RS2 comp wheel and the comp wheel from the hybrid. Notice that the RS2 one has had one machining operation performed on it. The hybrid wheel has had a few touches of the grinder applied to it.
Another point of interest is that the RS2 comp wheel is domed whilst the hybrid K26 is flat.

[twoqu]

The seal plates are matched to the comp wheels. Notice the recess in the RS2 one. You can also see the difference in the size of the centre bore. The RS2 one is for the 14mm piston ring seal. The K26 is for the 19.3mm piston ring seal. Another difference is that the RS2 uses one seal at the comp end whilst the K26 uses two.

[twoqu]

So from what I have seen, In order to graft the RS2 cold side onto anything else you would need all the components, comp cover, comp wheel, seal plate and the matching internal parts from the centre housing that I have pictured earlier. We know the centre housings are common and the bearings themselves both the thrust and the sleeve.

[Jamo]

This picture shows the actual turbo thrust bearing. It is located on two pins, one either side. As you can see, the bearing has a segment missing where the oil gallery is. So it is a 270 degree bearing. A 360 degree bearing would have virtually a full circle of bearing material. I believe that 360 degree bearing are available for this family of turbos. So thats something to investigate before rebuild.

Seems 360 bearing are available individually or in service kits.

Could this be perfomred easily on a new turbo or would it have to go to somewhere like AET?

http://www.melett.com/pdfs/KKK/3K%20K26.pdf

Also twoqu what part number do you have on the RS2 turbo you have?

As there were a couple of revisions and would be handy to know if you have the later revision of turbo.

[twoqu]

Jamo,

There was no tag on the seal plate. Looking at the small punch marks on the various components I gather I wasn't the first to visit! I'm just trying to clean the turbine housing up. It looks different to me than Paul's one. Doesen't have any numbers on the back if I remember correctly.

Here is a picture of the sleeve bearings from the inside of the centre housing. Notice the heavy discolouration on the bearing from the turbine end.

[twoqu]

Here is a picture of the turbine housing. This seems to have a different style of numbering than Paul N's one. The numbers are closer together and it is a lower case d.

[twoqu]

Here is a picture of one large crack. This runs from where the turbine scroll ends to nearly all the through the exit. There are eight further cracks around the inside of the turbine.

[twoqu]

Here is a pic inside the turbine entry. Basically the dark lines are cracks!

[twoqu]

This pic shows that there are no numbers on the rear of the turbine housing other than the symbol.
I have attempted to get an accurate measurement of diameter of the turbine exit. It is slightly bigger than 54mm, possibily in the 54.2mm region. Due to the amount of damage the turbine wheel suffered, I cannot guarantee that is the true RS2 dimension. However the exit does not look particularly damaged.

[twoqu]

This is one of three pics I have stolen from Paul N.
This crack originates in exactly the same place.

[twoqu]

Another of Paul's pics. Notice the difference in the numbers between this housing and the one I have.

[twoqu]

Another Paul N pic. Notice that the RS2 on the left has the 3552 designation but not the symbol. The one I have had a symbol but no 3552 designation.
So that would indicate that there are more than one version of the same turbine housing for the RS2. Clearly if one was a redesign, it failed in almost exactly the same way!

[A80Avant]

are thes pict.of Pauls stuff from the turbo he bought from me?Are all those cracks found on Pauls turbo or yours?

[S2central.net]

This is some great stuff by Robin... A nicely documented stripdown of the RS2 turbo.

The crack pictures are scarily familiar alright - both the turbine housings on PapVas' old RS2 turbo (now mine) and the one that Robin has stripped are cracked from years of thermal abuse.

I'm going to get a quote from AET for a 360 degree thrust bearing and a balance job... Plus I'll ask them about machining my S2 hotside for RS2 application - I'm blowing cold on the hassle of locating the right combination of 'small hybrid' wheels and such.

Also weird that the two cracked turbine housing are numbered slightly different. My one appears to be 1994 vintage... The spare S2 housing is 1991 and is in much better condition !


Paul