Originally Posted by jerg_064
1"...the factory hose to the intake is 1" ID....I just my CCV to atmosphere mod. Also keep in mind that on the factory closed system the turbo creates vacuum and PULLS the air out of the crankcase...Much like Header e-vac and belt ran vacuum pumps on drag cars, so with a CCV only or and inline filter/catch can/more tubing length (i.e. more restriction) you definitely don't want to go smaller than stock. I used 1" ID clear reenforced hose from Lowes'.
I got half a mind to take the oil filler off the pass side and find an elbow to fit in there and vent both sides like every gasser vent to atmos set-up.
I have installed a pressure/vacuum gauge on the oil dipstick to check the backpressure and/or vacuum after installing the ccv re-route (I installed a filter and returned the vent to the intake). Also, I did some pressure drop calculations using "blow-by" rates in cfm published by Racor. They recommended using 10 cfm flow for a well worn 6.0L engine (so this was a conservative rate IMO). At this rate, I calculated that you need AT LEAST 3/4 inch hose and you would be better off with 1 inch hose to avoid backpressuring the crankcase beyond 0.3 psi. THE PC/ED MANUAL STATES THAT THE MAXIMUM CRANKCASE PRESSURE SHOULD BE 0.3 PSIG. I used 1 inch hose to and from the filter.
I was hoping to get some vacuum, but the intake will not normally produce enough vacuum to put your crankcase under vacuum. Only at WOT accelerations, did I see a very slight vacuum being pulled - at most 1 inch of mercury. Typically, I saw a very slight back pressure- a few tenths of a PSI or less.
I was shooting for 0.25 psi or less backpressure at all times. I do not think I would have achieved this with 3/4 inch hose (according to calculations). I will say that the calculations required some fairly big assumptions and I tended to be conservative.