GT25R
- The first problem was that the exhaust flanges do not match, I plan to plug with an existing std and re-drill + tap
- the mount hole.
- The std lc mount studs are M10, but with the GT25R these are M8. Because the new holes slightly overlap the existing
- holes I will need to be careful to drill a true vertical and round hole prior to tapping. First job is to make to fixtures that I can bolt
- the manifolds on which keep the face of the flange normal to the pillar drill spindle axis. The other thing which I need to be
- careful about is that the cast material seems very hard, also the existing studs are stainless steel. The best drill and tap I
- can get are made from solid carbide, if they cannot cut this metal, not much will.
- Below is a picture of the 2 fixtures (angles of the flanges differ between the 2 manifolds) and the single drill jig which is
- adjustable to suit the small differences between the 2 flanges.
The drill jig plate is fully adjustable for alignment, and once positioned a vertical clamp prevents it from lifting.
Just need to obtain some second hand flanges and work can proceed (I want a route back incase all goes tits up ;-)
Finally got some manifolds, 1st job was to tighten any loose studs and trim flush with the face.
Drill jig carefully positioned, drilling started (with lube), the material was not as hard as I expected, which was a relief.
Next tapping the M8 thread, again with the material not as hard as expected this was quite easy too.
A nice clean thread was produced.
Next job was to adjust the port to match the gasket (the gasket already matched the turbine inlet port of the GT25R very
well so was an ideal template.
Black ink marker pen shows the material I need to remove.
Before After
Out of curiosity I had a look at the port match of std turbo turbine inlet to manifold outlet, I suppose not too
surprising was that there was no hand working of these ports, they were as cast and so their own tolerance
overlaps. Pictures here.