Bottom pic is the top of the tank. Filler neck's obvious, the other two pipes are the oil return which comes in at a tangent and centrifuges the oil to deaerate it. The pipe @ 90° to it is the vent. Pic at top right shows the outlet, detail of the pic up obviously can't be made out as it's on the underside of the pipe- typically a slot.
There's loads of ways of making 'em (no i'm not sharing detail pics of how i do it), some a lot easier than that allisport example off ebay and sometimes it gets a lot more complicated typically due to packaging issues... IMO ideally want at least 2.5:1 height-to-dia and sized for 1/3 of the volume to be air space i.e. 6 litres of oil = 9 litre tank. When there's no room for that end up having to shape the tank to suit the space and fit an air-oil seperator into it.
some baffle to seperate the air oil are just like wirewool, as the air goes past it hits the wore wool and drips back into the sump, the other way is using same principle but with plactic beads
One of the biggest mistakes people make is having too small a dia hose for the scavenge return, even down to 1/2" internal, also using hydraulic fittings without opening them out to relieve their restrictions,
I try to use -20 on the return for the main run. or go -16 for short run from pump to the bulk head then -20.
And a 1/4turn tap on the feed out of the tank that can be cable tied open and closed with the cable tie through the starter isolator key ! for cars that stand for long periods.
You don't really want a horizontal lip just below the oil return, the idea is to centrifuge the oil around the outside of the tank as it makes it's way down to help deaerate it. Dunno if this crude drawing of the top of the allisport example will help or not (between taking liberties with the layout, screengrabs to create a jpg and resizing the colours got messed up making it less clear)...
Both the vent and return pass through the tank wall, the former is terminated just short of the ID of the tank while the return stops past the centreline to spin the oil off the tank wall. The side of the tank acts as a baffle for the vent and note that it's positioned so that oil isn't getting thrown at it. Personally i'd say you don't want anything like wire wool or gauze anywhere near the thing. Didn't bother drawing any sort of lip where the top breather section meets the return stage, personally if using this design i'd have a vertical one i.e. the green cylinder passes through into the return section
As a general rule horizontal baffles do a far better job than verticle ones but if there's room for a decent height to width ratio the basic tank shape prevents oil from sloshing around too much anyway. If a conical base is gonna work (room/mounting it etc) then it doubles as a convenient spot for a horizontal baffle and/or joint (if making it a two piece tank for cleaning) as you need a joint there anywhere.
Not much really TBO
for a start I would have horizontal rings with holes as baffles I would not have the bottom tapered to the outlet and I would have the outlet slightly higher than the bottom because any contamination will lay at the bottom for instance I was filling a tank just before a stage start some numpty had pushed the aluminium seal down inside the oil can as i poured the oil in direct from the 5ltr container plop in it went, the car had to go, we drained the oil out later and there was the seal sat at the bottom chances are the pump would have mashed it but the flat bottom held it, even on a healthy car I have seen small debris held on the flat bottom, that would have gone into the pressure pump or worse jamming the relief valve.
Which 'swirler' design are you basing it on, this one which would be difficult to make and overkill in many respects (it's for something far more complicated and much larger than a car engine)
Or this Moroso example which is simple to fabricate
Although i'd offset the belled holes in the baffles so there isn't a direct 'line of sight' through them. Moroso notched the two lower baffles so the thing can be assembled
I realise it's probably a result of the rough sketch but you're drawing has the oil being deflected upwards. Centrifuge it off the tank wall and then have horizontal baffles or a swirler sitting a little lower to help as the oil loses energy on it's way down
Like i said, it's a bit overkill. Most important bits...
1. Decent size oil return that enters the tank at a tangent like the drawing in post #10 to centrifuge the oil
2. The vent is designed so that oil doesn't get thrown out of it. Both the Allisport design and central vent with a swirler accomplish this.
There is no absolute right or wrong way, everything has pros and cons to it
I think you are over complicating it,what revs is the engine doing? having as large a return from the scavenge pump is a big help on a high rev'er, I usually run my breather/s out into a small tank situated as high as possible, but have tubes quite deep into the breather tank so that the air has to do a 180turn then have a -3 from the bottom of the breather tank running down, into the main tank, but under the oil level, returning any breathed oil that has separated, back into the system. A -20 from the top of the breather tank down out to atmosphere, but below the bottom of the DST . Then if the car ends up on its roof any oil that comes out of the DST is caught and can run back in, when the car is righted.
Sorry to dig up and old thread is it not better to have the return on the main body of the sump so that as the oil returns it will spin around the body? Or is the above photo the preferred method, is there an advantage to vertical baffles vs horizontal