Cheers lads
Did you mean 'Kompressor' pistons Alex?
The Merc Cosworth had bores of 95.5
whereas my pistons are a Knats chuff under 83mm.
I've completed the dismantle now and the fun
really starts.......

As for 'machining' XRon40's, the rods I've got have had a file taken
to them to remove the tell tale manufacturers markings
(it's a secret remember) and presumably to allow the crank
to rotate some material has been removed from the rods around the bigend. And, (for goodness sake I'm reminded of a particular tea commercial
from way back/pass the monkey wrench) half the tops of the rod studs have also
been milled....I can't wait to see the difference in weight of each rod as I
can only imagine the lump must have been very poorly balanced judging
by the ovalised bores and broken pistons skirts/still at least the rod bolts
held (amazingly)for the massive 28,000 miles the engine has completed......
Whoever built this should be dragged out to the car park and kicked
repeatedly till the police arrive/still it could be worse guys 'someone'
might still be selling these and one of you could still shell out for one...
I'm off for a lie down whilst I contemplate the sheer engineering genius of cast pistons in a turbo charged motor!