Spook, I've added a few of my thoughts in red. I haven't heard of the value of introducing extra air into the engine (via a breather), only to suck it out with one stage of the dry sump pump. Seems like it'd be the same as putting a humidifier and a dehumidifier in the same room and letting them fight it out
Quote:
Originally Posted by spookypt
Hi everyone, I'm chasing some info....
My cobra basically is running a NASCAR Spec 351w. 4 stage dry sump with all the bells and whistles 13:5 comp bla bla.. And sounds TOUGH!!!
What I'm curious about is my dry sump pulls substantial vacuum and yet it isn't fitted with a crankcase vent. Have you measured it? Most guys are running 10 to 15" of vacuum with a vacuum control valve such as http://www.gzmotorsports.com/vcv102.html
It has a vent on the DS Tank but essentially the engine is sealed. As it should be, and as the pump is designed.
So at high rpm (say 8500) what stops it sucking its guts in. (Gaskets etc) Usually the only gasket that is at risk of being sucked inwards is the rubber seal at the front of the oil pan. Doesn't seem to have been a problem with SBF motors in the past.
I also understand without this its bloody hard to get piston ring seated? Vacuum in the crankcase sucks the rings out to the cylinder walls, so it helps with ring seal. |