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These pistons may be what is needed for higher output power mods, but does not make sense for a stock or lightly modified system.
But just for fun, how do the JE pistons compare to the Saab pistons?
fit AB $92 each
fit B $83 each
fit +0.5mm $222 each
fit +1.0mm $224 each
I think these include the rings, pins and clips, but if not add more $$$,
So for any overbore situation the JE pistons are not more expensive!
The stock pistons handle 'normal' loads well, and do not fail from being overloaded by the normal forces. If that were the case, we would see overload failures all over the place. What is happening is that there are a few vehicles with cracked pistons. What overloads these? Knocking certainly could cause this. And if such knocking is occuring, the JE pistons might not survive that either. But what is the root cause and solution? I do not know. There has been speculation that high amounts of crankcase oil mist might trash the effective octane. But that in turn requires that there be high amounts of blowby gases.... what caused that? A cracked piston could, but now we are talking about a post failure effect. Others have suggested that the ECU makes things lean on a transition to less throttle while still on boost. That could do it, if that is indeed the case. But again we do not know. If Saab knows, perhaps a fix for this was buried in one of the last ECU software updates. So there might be some merit in collecting data on these failures that also includes the ECU software versions.
If one were getting off of boost to a lower boost level and the ECU was managing all of the sensors, TB and injectors... could there be a problem where the TB does not close the throttle as expected and the air flow exceeds the air flow called by the ECU?... could the ECU then be caught fueling for a lesser air flow created a lean AF? Perhaps a fouled TB interfering with the throttle plate or simply a TB malfunction. On can imagine a throttle sticking in a fouled TB bore near closed/idle postions, but it does not seem possible when the throttle is opened widely.
So we are looking for a loss of effective AF octane. This could be from excess air or oil misting. I have trouble believing that the ignition is in some cases firing way advanced... but could a flakey crankshaft postion sensor cause this?
Another blowby gas generator could be stuck rings, loose headbolts allowing gases to reach oil supply or drainage passages, blowby past exhaust and intake valve stems when on boost, defective PCV check vavle. We do have all of these loose head bolts. Perhaps there is a connection. We would need to have the head bolt torques checked prior to head removal. If we found cracked pistons and heads that were tight, then we could rule out this connection as the sole cause.
, Wed, 23 Mar 2005 21:00:36
, Thu, 24 Mar 2005 12:12:04, Wed, 23 Mar 2005 19:58:06, Wed, 23 Mar 2005 20:08:05
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