Post by
WDRacing »
https://forums.nicoclub.com/wdracing-u3125.html
Thu Mar 07, 2013 5:04 am
The part in the video is called the intake port on the head. On the opposite side there is a matching exhaust port. The crud he's talking about is what I was referencing when I said your motor ingests blow-by gases from the sump.
To elaborate just a little, when normal combustion occurs some of the combustion gases leak past the piston rings and into the sump. In the sump they mix with the oil. This is the main reason your oil gets dirty, not engine wear. Blow-by is greatest when the engine is under a load, max load occurs at peak torque. But that doesn't matter, just think about blow-by being the worst whenever you're accelerating.
Under acceleration the sump actually gets pressurized because of the blow-by. It's the job of the PCV system to remove this pressure. The PCV system works on engine vacuum. the long short of the PCV is that it sucks blow-by out of the sump, through an air/oil separator and feeds it into the intake manifold to be re-ingested. It's done this way because venting it to the atmosphere would be bad for the tree's and fuzzy little bunnies. The EPA doesn't care that ingesting combustion gases mixed with oil gums up your entire intake manifold, pistons, valves and basically anything else it comes into contact with. It also reduces your octane ratio. So if you have bad blow-by and your motor requires 91 or better octane, you're not getting it regardless of the fuel you're using.
This is why a lot of people, especially those that use some sort of power adder, run an extra catch can, oil/air separator. Or they have the valve cover vented to the atmosphere. Some people use a vacuum pump, be it electric or belt driven. I'll be using a vacuum pump on all of my future builds. Using a vacuum pump not only removes blow-by, but if causes the piston rings to seat against the cylinder walls by creating a vacuum in the sump. More seal = more efficient combustion.
just kidding it's a Rogue forum joke.
