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Engine changes:
The 9-5 engine has "low tension" piston rings, which increases the amount of blowby (products of combustion into the crankcase) which adds stress to the oil. To help reduce sludge, it runs the oil at a higher temperature, which also reduces stress to the oil. As a result, oil changes are very, very important for this engine.
The 9-5 features an industry standard "geneva wheel" oil pump mechanism, versus the much more robust (and presumably more expensive) gear type mechanism. To be sure, the geneva wheel mechanism is completely sufficient for automobile engine oil supply, but because it is more easily damaged by stuff in the oil (the oil pump sees the oil before the filter does) there is a very fine mesh screen over the oil pickup. As a result, oil changes are very, very important for this engine.
The original PCV system designed for this engine was elegant and effective. Unfortunately it failed to meet US EPA requirements. Long story, but essentially it used a solenoid to switch paths when on/off boost, which required the ability to set a code if it failed. But there was no OBD-II code for failed PCV solenoid, so they had to use a less reliable, less effective Rube Goldberg conglomeration of hoses, check valves, and different orifice sizes, which took entirely too long to get right. As a result, until 2004 the engines had inadequate crankcase ventilation from the factory, and engines made earlier need PCV kit #6 for proper crankcase ventilation.
For a period of time, Saab's spare parts network was distributing oil pump assemblies that failed to meet Saab's own specifications, and therefore put out inadequate oil pressure. Whether any of these oil pumps made it into original production, we don't really know. Best idea is to measure oil pressure, and if it fails to meet the spec, replace the oil pump. The ones in the spare parts network now are fine.
Bottom line: for factory levels of tuning, so long as the engine has not been sludged and the PCV is up to date and the correct oil is used and changed often enough, the engine will not blow up. You can run full boost for as long as you like. People are reporting two and three hundred thousand mile longevity.
The only sure way to tell if an engine is sludged is to drop the oil pan. If you then find excessive crap on the oil pickup screen, you could either tear down the engine and have the block "hot tanked" or install Bob Bright's trick oil pan, the one with an access hatch below the oil pickup tube.
When you increase performance beyond factory levels, you are increasing stress on all the components in the engine (assuming you actually use the extra power that is available to you). In that case, I would recommend that you "blueprint" the engine: rebuild it and make sure that the tolerances are as close as possible to the design, not just "within acceptable tolerances." Also, I would definitely install stronger pistons, such as the ones that site sponsor Nick Talliafero sells.
posted by 24.165.15...
, Mon, 17 May 2010 15:01:29
, Thu, 13 May 2010 10:12:22, Thu, 13 May 2010 05:56:58
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