03-10-2018, 08:21 AM
We all await the outcome with great interest. I hope the tale does not peter out as so many other puzzles have.
( I think we are still waiting the outcome of the mystery drive clonk video of a few years ago!)
In such events it is often a puzzle whether the heating both preceded and followed mechanical failure, or just followed due to the leakage paths. I encountered a similar mysterious case with another make, of modest performance, car not being very hard driven and with nothing noticed by the driver.
I can understand weak mixtures causing trouble on a race car flat out and reliant on rich charge for cooling but not sure of the mechanism at moderate output. There is nothing more weak than a diesel and these survive at colossal outputs! With other makes I have driven extensive miles on somewhat weak mixtures to the detriment of valves, seats, but not pistons. Perhaps the slow burning causes a burning mixture to be compressed? I have had pistons on others crack across the crown such that blow through was notable, but no melting of piston.
For those that know far less than Alan the detonation failure sequence may be of interest. It is reckoned that normally an insulating layer a few molecules thick survives through each explosion .(Despite the colossal flame temp the film of oil on upper cylinder survives and often oil use is nil). But the shock waves from detonation (pinging) strip the insulating layer away and a damaging amount of heat is conducted to the piston crown and elsewhere. Once a leak path occurs the flame ripping through makes matters worse.
( I think we are still waiting the outcome of the mystery drive clonk video of a few years ago!)
In such events it is often a puzzle whether the heating both preceded and followed mechanical failure, or just followed due to the leakage paths. I encountered a similar mysterious case with another make, of modest performance, car not being very hard driven and with nothing noticed by the driver.
I can understand weak mixtures causing trouble on a race car flat out and reliant on rich charge for cooling but not sure of the mechanism at moderate output. There is nothing more weak than a diesel and these survive at colossal outputs! With other makes I have driven extensive miles on somewhat weak mixtures to the detriment of valves, seats, but not pistons. Perhaps the slow burning causes a burning mixture to be compressed? I have had pistons on others crack across the crown such that blow through was notable, but no melting of piston.
For those that know far less than Alan the detonation failure sequence may be of interest. It is reckoned that normally an insulating layer a few molecules thick survives through each explosion .(Despite the colossal flame temp the film of oil on upper cylinder survives and often oil use is nil). But the shock waves from detonation (pinging) strip the insulating layer away and a damaging amount of heat is conducted to the piston crown and elsewhere. Once a leak path occurs the flame ripping through makes matters worse.