Oil baffel
10-20-2017, 11:23 PM
#31
Former Sponsor
10-21-2017, 11:18 AM
#32
Nordschleife Master
Different cars need different systems/ideas, totally dependent upon how they are driven.
Regardless of which engine family, the condition of the engine, or how it is driven, they all will benefit from a properly engineered oil baffle under the filer neck.
There are very good baffles, medium useful baffles, and baffles that have very limited usefulness. Pure common sense eliminates the baffles with limited usefulness. Just look at what you are about to use or buy and think about a rainstorm of oil hitting that baffle. If the part of the baffle that hangs down into the block has open sides, the oil/air is going to blow right around the sides of the metal hanging down and have a direct path to the opening/secondary baffle at the filler neck, going right through the open sides.These baffles are largely home made, "early" attempts at making something to help, or baffles from someone who doesn't have a clue what is happening inside the engine.
We've just made a post in another thread (https://rennlist.com/forums/928-foru...mparisons.html) showing how how my baffle works. There was a tremendous amount of engineering and testing involved in the design of this baffle.
Cars that have good rings, valves, and guides and are Sunday cruisers or daily driven cars which seldom get run up in the higher rpms can use just an additional baffle under the filler neck.
Vehicles that are run harder generally need more that just a baffle. I've got several different levels of pieces, completely dependent upon the model year, and how the car is driven. Most all of my various "systems" abandon the filler neck return to the intake. At high rpms for extended periods of time, there is no possible way to keep the filler neck area from becoming completely packed with oil and it becomes impossible to separate the air from the oil, in that constrained area.
Regardless of which engine family, the condition of the engine, or how it is driven, they all will benefit from a properly engineered oil baffle under the filer neck.
There are very good baffles, medium useful baffles, and baffles that have very limited usefulness. Pure common sense eliminates the baffles with limited usefulness. Just look at what you are about to use or buy and think about a rainstorm of oil hitting that baffle. If the part of the baffle that hangs down into the block has open sides, the oil/air is going to blow right around the sides of the metal hanging down and have a direct path to the opening/secondary baffle at the filler neck, going right through the open sides.These baffles are largely home made, "early" attempts at making something to help, or baffles from someone who doesn't have a clue what is happening inside the engine.
We've just made a post in another thread (https://rennlist.com/forums/928-foru...mparisons.html) showing how how my baffle works. There was a tremendous amount of engineering and testing involved in the design of this baffle.
Cars that have good rings, valves, and guides and are Sunday cruisers or daily driven cars which seldom get run up in the higher rpms can use just an additional baffle under the filler neck.
Vehicles that are run harder generally need more that just a baffle. I've got several different levels of pieces, completely dependent upon the model year, and how the car is driven. Most all of my various "systems" abandon the filler neck return to the intake. At high rpms for extended periods of time, there is no possible way to keep the filler neck area from becoming completely packed with oil and it becomes impossible to separate the air from the oil, in that constrained area.
Our experience has been different on breathing out of the chimney. With John's baffle box _and_ hooking up the hoses the way we do, we're only getting oil mist and water vapor from the breather ports. This is with a number of 5.0L engines that are spun to stock redlines, so it may not apply to larger displacements and higher rpms. The cars I'm talking about also have street tires, so we're talking about 1g or lower accelerations for most part here. With those caveats, when we breathe out of the oil filler neck top and route the gas thru the BMW cyclone separators, we get basically no oil out of the breather hoses. For example, the two Gatorade bottles on my car for testing are completely clean.
Breathing out of the top of the oil filler neck (like GTS does) helps in most operating modes, but then you don't want to breathe out of that port during hard braking. Hard braking pushes the oil spray that's on the baffle box walls and oil filler neck walls up the the oil filler neck, which is a potential problem if you breathe out of the oil filler neck top under deceleration. All factory configurations of the breather system do, they vent from the oil filler neck 2mm port to the intake manifold plenum which has vacuum with throttle closed deceleration. I don't think that's the best way to design the breather system. Similarly, the factory system breathes out from the rear valve cover port during hard acceleration. This makes no sense to me, as the oil is pushed backwards to the rear of the engine under hard acceleration. In my opinion, the correct way to hook up the breather system is to breathe out from the front of the engine during hard acceleration and breathe out of the rear of the engine during throttle closed deceleration -- whether you breathe out from the chimney or the valve cover ports.
In the end, I think most people (including me) are making a too big of a fuss of a small amount of oil making it to the intake to be burned. If it's some drops here and there, who cares? Stepping back, it's only a problem if a large amount of oil makes it to the intake, causing detonation, coking of the piston tops, and noticeable oil loss. There are more severe oiling problems in the 928 engine that are largely unrelated to the breather system and that become increasingly problematic as the displacement and rpms are increased. A perfect breather system alone that never lets out oil and that keeps the crankcase cycle average pressure close to atmospheric pressure isn't going to solve those problems.