Exhaust progress

The exhaust is more or less done at this point - all we have to do now is add the weld-in bungs for the EGTs, add the final tertiary section with a lambda bung, paint, and wrap the exhaust.  It's fully welded and leak tested at this point.  Costi did all of the welding before break, and I just finished the final merge collector weld and touched up a couple of leaky spots.

The initial leak test showed only three leaks (two were small, one was fairly large).  All three were sites with high concentrations of impurities - this just shows how important having a clean weld is - bubbles and pockets form too easily when the weld gets contaminated and these are difficult to remove.

Leak testing the exhaust - the four inlets are sealed by the head, and the exhaust is pressurized by continuously blowing air from the hose.  While the exhaust is pressurized, we spray soapy water over all the welds, carefully checking for bubbles which indicate a leak.