Pistons not cracking after all!

Well the head was removed and it was noted that the pistons look fine, certainly nothing like the bore scope image suggested we would find. Due to the poor compression test results I requested to carry on and strip the bottom end, however once the pistons were removed they showed nothing wrong with either the rings or ring lands!?

Potentially I could now save a bucket load of cash (although already bought the Arrow rods) and carry on with a stock bottom end, but that would mean swapping the cams from 403’s to 402’s due to clearance issues. That in turn would also mean more cash could then be saved from not needing valve springs. However, I don’t want to compromise the spec I have already decided on so it is still full steam ahead 😉

Can’t really explain the orignial bore scope image though, must be a low resolution trick of the eye. Possible the poor compression result is down to the top end, should find out in the next few days.

Cracked Pistons Pistons Pistons Pistons Pistons

Mapping results [aka Piston damage!]

Well fitting the R3 exhaust manifold and running unmapped for only 3 days has caused some pretty serious damage. Dan at SJM ran a compression test before mapping and found the car was only kicking out 170psi, about 20-30psi down on what a healthy example would be.
Seems that the manifold has caused the car to run very lean causing detonation, which has crumbled the pistons and fried the piston rings! Dan uploaded a generic pre-cat delete map to help stop things from deteriorating but ultimately custom mapping it would have been a waste of time. Looks like a rebuild is on the cards.

Here is the view from the bore scope:
Cracked Pistons