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Just adding a data point to the knowledge base: When the engine was dropped for coolant fitting welding, the Cup/RSR crankcase breather was installed. So far (~700 track miles + ~1000 street miles) it has not caused any leak.
No idea if it was giving me that extra 5-10hps, though.. but if it is on the Cup/RSR, it is good enough for me.
I think some clarity may be needed. The RSR/late Cup(03-05 long rod motor) crankcase breather is the same thing. The Main seal on the 04-05 Cup is what You want is double lipped and identical to the RSR seal. The crankcase breather valve can be installed on the early Cup(AND MK1 GT3) with no ill effects. If the RMS begins to seep/leak it will only do so when the engine is stopped, it will not leak when running. We have done this on 3 early cars so far and not one of them has leaked yet. All these cars we did it from the top with no trans removal yada yada...I carry a late seal with me all the time for when/if it does begin to leak.
so am I right in my reading of this that the 05 996 cup engine already has this breather fitted?
How can a crankcase breather increase HP?
Hw does it work?
good question. my assumption is that the rsr breather restricts blow by gases to the intake more than the regular breather under full load, but only momentarily until the crankcase pressure increases to some point. The crankcase acts like a reservoir to hold blow by gases instead of going to the intake and displacing fresh air and fuel. It's this incremental air and fuel which would have been displaced that creates more power. When the reservoir fills up (i.e. crankcase reaches a certain pressure) it is in equilibrium and whatever is blowing by goes to the intake. You could also make an argument that the total amount of blow by would be less with higher crankcase pressures but I don't think you can increase the pressure high enough to make a meaningful difference. If emissions were not a concern you could vent all the blow by gases to atmosphere instead of to the intake and also maintain low crankcase pressure to avoid seal leakage. Just my opinion.
01-29-2014, 02:12 PM
