Race Engine Forum UK

Hello,

I just got an email from a customer, reporting piston failure. THe customer has Marea 16v, that his mechanic converted to turbo (stock pistons have been dished to reduce CR). He purchased engine management system from me.

His mechanic diagnosed that pistons have failed from lean conditions detonation (due to insuficient flow through the fuel pump). I am more into believing that pistons could not stand the pressure that was present under boost, so I suggested aftermarket items.

Here are some photos, any diagnosis help will be appreciated.

http://www.quartermile.ws/forum/viewthr ... &pid=47952

http://www.quartermile.ws/forum/viewthr ... &pid=47953

http://www.quartermile.ws/forum/viewthr ... &pid=47954

Thanks,
Nikola[/img]

Ive seen the same thing done to a 1.6 8V. It ended in the same result too. You cannot expect much from such an engine.

Steve,

why not, what is the limiting factor? Let's say if it had forged pistons and sufficient fueling and correct ignition advance, would it be quite safe?

I forgot to state CR (8:1) and boost pressure (0.8 bar). Any hints on what may have caused such a damage?

Regards,
Nikola

well, that is detonation, all lands fractured. Turbo pistons have heavier (thicker) top and second lands, but judging by the severity of the fractures they would not make any difference, the lands might hold up but the phenomenon would simply exhibit itself in other ways - crown and top edge eroded, scorching.

No doubt in my mind - this engine has failed due to any or all of: ignition timing over advanced for turbo use, too lean, exhaust back-pressure, overheating inlet air, wrong plugs, fuel octane too low/boost too high etc etc., in other words - the usual suspects that lead to 'converted-to-turbo' engine failures.

GC

Thanks... at least I know now how to distinguish one from another...

Nikola