Unfortunately I recognized some cracks in my turbine housing (GT2871R) when changing my manifold (to weld and port it). An exchange housing (after only 7000km of driving) cost 160usd at ATPturbo inclusive shipping - this is ok.
See the picture 3451(http://service.gmx.net/mc/2mlUPT9aKTqheE7H2DpdE28QgvmbNp
- press "gmx mediacenter starten")

When optimising the manifold my specialist Hartmut Lohmann (formerly member of motor tuner F1-BMW) and me recognized two things (at GT2871R) who definitely will cause a loss of performance.

1. inlet of GT2871R - a terrible angle (two bevels) of the compressor housing, which leads to the compressor wheel - have a look at this:
http://us.st11.yimg.com/us.st.yimg.com/I/cheapturbo_1902_41097802
and now our changes:
Pic 3455
my specialist chamfered the complete inlet to get a better flow to the compressor wheel.
Ps: the bigger Garrett turbos all have this curvature...perhaps it is too expensive in production...

2. the inlet to the manifold - here we recognized that the outlet of the manifold is bigger than the inlet of the turbo - means - the exhaust gases - accelerated almost to sonic speed - will hit the border of the turbine housing...
therefore we ported the inlet of the turbine housing, too.
see pic 3457.

ps: Hartmut told me, that a lot of motorsports tuner let adapt their turbo inlets to the manifolds... this normally results in more predetonation...

Juergen

Morning Juergen <img src="/forum/images/graemlins/smile.gif" alt="" />

That's very interesting, I have done the manifold as there is an obvious step down in diameter from the exhaust port outlets to the manifold. We ran out of time to look at the turbo itself, but would make sense there also.


Do you know why this is,.. this is the opposite of what you would expect,.. did you mean it this way?

regards

joe

Hello,

in German language „you can go towards more predetonation“ means – you are able to adjust your ignition towards more power… because of later pinking.
Maybe you understood the opposite…sorry!
Thus after porting the inlet of the turbine housing (for a Audi A3 1,8T) a well-known tuner in Germany was able to gain 2° more predetonation (towards more power)… that’s really a lot!

Juergen

You could alternatively fit the 0.70A/R T04E or T04S compressor cover onto the turbo as this has a tapered shroud anyway and has better flow properties. The HKS equivalent turbo has this and the shroud is also polished which further improves spoolup

very very interesting Juergen!

Can all that work be done using a Dremmel?
[I bought one a couple of months ago anticipating it'll be usefull for various car related bits, so I'd be happy to spent a few hours myself when my turbo arrives!]

cheers

I think, for the compressor housing a dremel and some sand paper with skilled hands is enough.
For the turbine housing you will need a carbide cutter...
Juergen