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, Fri, 11 Feb 2005 08:00:20
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The new rods were lightened, but not neccessary stronger because of that.
The reduction of weight is a concern for reciprocating mass where the loads increase with the square of the RPMs. If you flog the engine to the red line, then that might be something to consider. But many folks like to drive on boost at lower gears and for those applications, an expense to reduce the weight of the rods might have no benefit, real or percieved.
So when did the nitrided wrist pins get introduced?... with the first Viggens or with the increase of power with the 9-5 230-250 HP engines. Pistons also lightened at some point as well? We know that some Viggen/Aero pistons can fail (to both lightened and earlier?), but it is not clear that the pistons are lacking or simply damaged by knocking. There are some credible thoughts about the/a knocking problem, but with Saab being tight lipped about these things, we simple do not know the truth. If there is knocking happening, then some super dooper aftermarket pistons may not standup in such a situation. Some speculate about a lean event coming off of full boost, and other speculate about PCV gases carrying oil mist into the intake that kill octane and leads to knock. With all of the oil sludging and PCV systems not been able to cope with blow by gas volumes, this mechanism does seem to have some merit. It fits with the pattern of everything else that is going wrong. But once a piston cracks from any cause, the blow by gas situation gets insane and the oil mist situation might be an effect and death mechanism, but not a primary pathology.
So ARC interals the same as Aero? Good question for the EPC, but do not have time for that today. Perhaps a current engine swap is much better than a rebuild for cost effort as well as updated internals. Lower miles on cams and bearings also good. Need to see if exhaust valves and cams are the same as well.
, Fri, 11 Feb 2005 08:00:20, Fri, 11 Feb 2005 16:39:07, Sat, 12 Feb 2005 07:28:51, Sat, 12 Feb 2005 17:32:43
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