Expert
Posts: 4458
Location: Jelling, Denmark | KLAS - 7/8/2016 6:17 PM
poor quality of the gaskets has been a problem some time ago. IIRC with the black Payen it was due to relocating the factory and poor setup of the machine. depending on what type you use
in general i would say if it only happens during racing that may be a problem with cylinder pressure being high enough to lift the head a bit and than burn the gasket. using the Metro Turbo torquing procedure may help, lightly oiled threads and 70Nm.
or it may be ignition related detonation, damaging the weakest link first, in your case the gasket. retarding the ignition may help.
or one cylinder is running a bit leaner and hotter, damaging the gasket. you won't see that at an exhaust gas analizer as it only sees all exhaust gases from all cylinders, not from individual ones.
Yes I use the black Payen bk450 gasket like most if not all mini racers. the gaskets were bought recently.
A guy suggested that the recent skim of the the cylinder head and block were enough to put the compression "over the top" and that the gaskets burn because of this, so this is in-line with one of the reasons you give.
He suggested a different torquing procedure and to torque it down harder. normally I torque it as haynes say, I believe its 7.5kg cold. he suggested to do that and then loosen all bolts a quarter of a turn, tighten them a quarter turn again and then torque them to 7.5-8.5kg with the engine hot. |