Broncobowsher
Total hack
- Joined
- Jun 4, 2002
- Messages
- 35,630
Air enters one valve cover, washes the air in the engine, picking up water vapor and other blowby stuff. Goes through the PCV valve and into the vacuum of the intake manifold. Idealy at the base of the carburator so there is an even distribution to all the cylinders.
The fresh air in is like opening a second window in a house on the other side from where you have a fan flowing stale air out. Keeps everything fresh.
A side benifit to the vent is under high loads there isn't any vacuum sucking. Blowby is at its highest levels as well. So the vent lets the gasses escape without building pressure in the crankcase.
EFI (factory) changes things up just a little. PCV pulls out of the valley instead of the valve cover. The make up air is metered by the MAF, the connection is between the MAF and throttle body. The MAF reads air entering the engine. The PCV is part of the air entering the engine. The fresh air that just goes through, still needs to be calculated and fuel added. Blowby, falls into two catagories, burned exhaust which does not need any fuel added and compression, which already has fuel added and doesn't need to be accounted for again. Non-mass air EFI doesn't need the calculation and is more imune to PCV plumbing. I've had EFI engines that had a rough idle because the oil fill cap was off and it was getting unmetered air through the oil fill.
The whole ides of PCV is fresh air flowing through the engine. Bad stuff coming out, burned. One of the best things ever done. Engines run longer as the fresh air keeps the insides cleaner. The blowby doesn't sit in the engine. Race cars don't bother with PCV, they get rebuilt so often it doesn't matter.
A hose from a valve cover to the air cleaner is very common. not to suck air out of the engine. Manifold vacuum does the sucking. But to give the engine fresh filtered air to make up the the sucking the PCV does. It also collects the blowby at full throttle and lets it go into the engine to get burned
The fresh air in is like opening a second window in a house on the other side from where you have a fan flowing stale air out. Keeps everything fresh.
A side benifit to the vent is under high loads there isn't any vacuum sucking. Blowby is at its highest levels as well. So the vent lets the gasses escape without building pressure in the crankcase.
EFI (factory) changes things up just a little. PCV pulls out of the valley instead of the valve cover. The make up air is metered by the MAF, the connection is between the MAF and throttle body. The MAF reads air entering the engine. The PCV is part of the air entering the engine. The fresh air that just goes through, still needs to be calculated and fuel added. Blowby, falls into two catagories, burned exhaust which does not need any fuel added and compression, which already has fuel added and doesn't need to be accounted for again. Non-mass air EFI doesn't need the calculation and is more imune to PCV plumbing. I've had EFI engines that had a rough idle because the oil fill cap was off and it was getting unmetered air through the oil fill.
The whole ides of PCV is fresh air flowing through the engine. Bad stuff coming out, burned. One of the best things ever done. Engines run longer as the fresh air keeps the insides cleaner. The blowby doesn't sit in the engine. Race cars don't bother with PCV, they get rebuilt so often it doesn't matter.
A hose from a valve cover to the air cleaner is very common. not to suck air out of the engine. Manifold vacuum does the sucking. But to give the engine fresh filtered air to make up the the sucking the PCV does. It also collects the blowby at full throttle and lets it go into the engine to get burned
