Originally Posted by Jon(m600)
So is it wrong to vent from both cams (this is what i was told)because mine is.
Its not "Wrong" to breath from there but its not optimum.
You MUST "IMO" Breathe from the crankcase direct as well.
Pressure build begins mainly in the sump but dont let anyone tell you it doesnt reach the head as this is a myth and is EASILY proved.
Blow into a balloon.
Does the pressure you just blew in the bottom affect the bottom of the balloon only? Or does it compress all the air in the ballon and thus change the air pressure in the whole balloon pretty uniformly and inflate the whole thing at once? Ok....Good, thats that Myth squashed.
As well as the fact compressing any volume of air is a uniform task regardless of where the air is introduced, there is also the fact that valve guides can and do leak a little air into the cylinder head space.. especially ones that are running 2bar plus positive pressure on them. Its only a little, but every little counts...
What "Releaving" the pressure via the head
alone or mainly does do that is poor, is it allows the compressed air flowing upwards to your breather outlets slow the return of oil to the sump.. this isnt ideal and can cause the sump level to drop below ideal, risking expensive engine damage/failure. This is the main reason why you must also breathe from the crankcase
mainly or as well as.
Also bear in mind that breathing from BOTH sides of teh crankcase is prefferable to stop any oil surge covering the breather port in use and essentially dissabling your breather system at a critical time. (This is what happens as std when she dumps oil everywhere after a thrash..lol)
The final point to note is this.
It pisses me off everytime i see a nice new shiny and expensive breather on the market that has say.. for arguments sake... 4 nice 16mm intake ports, perhaps 2 for crankcase and 2 for camcover.. great eh? 4x the std breather outlets
It also has an oil return.. brilliant, should save a little on oil consumption/loss...
Finally it also has a 1x 16mm or slightly larger return to atmosphere/airbox for the relieved sump pressure...
Erm... who can tell me whats wrong with this design?
