aryasura wrote:
>
> I installed Mikunis on my 311 this weekend, and I wanted to find out
> what to do with the blow off on the top of the engine
> which is hosed into the SU airfilters.
>
> Excuse me for ignorance of the correct part numbers, terms etc...
>
> Can it be plugged ? If not where should I re- route it?
>
> ed
> in NYC
No it can't be plugged. It is a crankcase vent and if you plug it pressure will
begin to build up in the crankcase. This causes the rings to seat poorly, as it
is the pressure differential across the rings that makes the rings seat against
the bore and ring lands (and not the static ring tension as many folks think).
Excess crankcase pressure buildup will also cause the engine to leak oil.
The best solution is to recreate the original venting system, however with some
carb conversions this is more difficult than the avg. DIYer is willing to deal
with. At the very least all stock breathers should be vented to atmosphere
through some sort of filter. If you car had a PCV system originally and you opt
to go with simple venting to atmosphere, you may find you develop oil leaks,
don't quite get the power you expected and/or start burning a bit more oil. If
so, what you have done is not adequately venting the crankcase and pressure is
building up.
There is a system racers run (though most racing bodies have outlawed as an
unfair performance advantage it for some reason) that uses both manifold vacuum
and the draw of fast moving exhaust gases to actually draw down pressure in the
crankcase. The system is called an evacupan system and it really works if your
exhaust system doesn't develop back pressure. It can create a significant vacuum
in the crankcase, and this can boost hp figures quite a bit due to better ring
sealing. So, do not discount this issue as unimportant, as the crankcase must be
properly vented for the engine to run properly.
Marc Sayer
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