Another small update and more bad news...
Upon inspection of my cylinder head it was revealed that my
intake guides have all worn on one edge. JP has never seen this on a 1.8T head before - it's normally always the exhaust guides that wear, causing the valve stem seals to go.
Like my block, cylinder #1 is the worst affected - which begs the question, what has caused this?
I noticed that the car was consuming a lot of oil after the hybrid work was complete, but seeing as all this work was done in one hit (turbo, rods, WMI, etc.) then it makes it impossible to narrow anything down.
The only plausible explanations I can think of are:
1. Debris entering the intake and causing wear
2. Valve guides manufuctured from too soft a material, breaking away and causing the scoring in all bores
3. Running WMI that is too strongly concentrated (50:50), causing some form of crystallization that was then ingested into the engine, causing wear. We found that the WMI nozzle was blocked with some form of solidified chemical after just a couple of months of usage.
4. Unknowingly running the car on full boost when the WMI nozzle was blocked for a few hundred miles with very high CFs - possibly damaging the internals?
The engine only started consuming oil after the hybrid work was complete (or at least, became noticeable - perhaps the extra power exacerbated a
problem). Either way, it's a weird one - I just want to be sure that I don't put it all back together for it to happen again...
I find it hard to believe that WMI may cause this issue directly by consequence of a highly concentrated mix as a lot of people now run these kits - though how many have had their engines apart since. Also, you wouldn't expect debris to get in the exhaust guides; more likely they've broken down over time.
Needless to say we'll be meticulous in checking that everything is completely clean during reassembly, and I'm tempted to run a slightly more diluted mixture and wind back the timing if necessary. We'll see.
On a more positive note my pistons have now been machined by JE and are on their way to the UK along with my Ferrea valvetrain so there should be some more movement soon.