Tazz9924
Tazz9924 New Reader
3/4/23 10:41 a.m.

So im going to diy up an oil pan baffle, i can make things well but i want to know the theory better. I have an oil pan for an ej subaru that is heavily shortened compared to factory but still maintains the same capacity. I want to know that my plan wont hurt more than help. Im curious of the opening size of the trap doors, capacity around the pickup etc. So here's my initial design, minus the openings for the trap doors, and the doors themselves:

I cant run an aftermarket solution because they would all touch the ground. 

And the metal is 1/8th because im welding it in, and with dissimilar aluminum's, oil etc id rather weld thick. 

jimbbski
jimbbski SuperDork
3/4/23 6:13 p.m.

The size of the trap doors that I had on an oil pan was about 3"X 1". The openings in the baffles was of course a bit smaller so that the doors would seal when the oil slung against it due to "G" forces. 

adam525i
adam525i GRM+ Memberand Dork
3/4/23 6:28 p.m.

Make the doors as long/large as you can without them interfering with each other or the pickup. You should also do something to limit how far they can open so they don't flip up the wrong way or touch each other (they will also close quicker). You will want to seal off the outside of your 4 sections to the walls of the pan so the oil is forced into the centre section and doesn't just run around it. The stock clearance unde the pickup is probably what you should aim for. A horizontal baffle sealed to the top of the vertical baffles will keep the oil from running over the top of them, your's looks fairly tall so that is good.

You mentioned the pan has the same capacity as stock, if you are doing all this work and have the space for it, adding capacity on the left and right of the pan for long sustained cornering is never going to hurt.

Here's the pan I modified for the M30 in my E28. You can see the bent hinge pin to stop the door from opening too far with the other end tacked to the hinge itself to keep it from moving. I bought my baffle doors from McMaster, I used this and trimmed them to size.

frenchyd
frenchyd MegaDork
3/4/23 6:39 p.m.

In reply to Tazz9924 :

Location, location, location!!!!  Don't just put them in the pan. Run them right up to the mains in the block!    Use CAD  ( card board aided design ) to ensure they are snug against the mains. 
   One handy hint.  When making trap doors use commercial hinges.  Sticky homemade hinges  can really  mess up the trap doors functioning.  Hinges come in plenty of sizes. In both steel and aluminum. 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
3/4/23 6:40 p.m.

I was going to make one for an EJ205, then discovered I could buy one with trapdoors and such as for $100.  No way could I make something as nice in the time it takes me to make $100 of fun money.  (Not just make $100)

The key thing in a Subaru is not necessarily keeping the oil near the pickup, but keeping it from slopping up out of the pan and into a cylinder head.

This unit does require removing the stock "windage tray" which was designed just to keep oil from hitting the crank.  Without a scraper, these largely serve to ensure the crank is running in a bowl of oil, slightly defeating the purpose.

 

That helps in one direction.  A neat thing I saw in a drag race oil pan was not trap doors per se, but some 1" steel balls that were contained in little cages.  The cages would go on the inside of your box and the balls would seal against holes just small enough that the balls can't go through.

From what I understand, they were to fight the oil running forward away from the pickup after a burnout, and they could actually be heard knocking into place.  My inner 13 year old would want to make the balls out of brass, because they clank smiley

 

EDIT: Found the article! https://www.motortrend.com/how-to/sucp-0006-racing-oil-pan/amp/

Tazz9924
Tazz9924 New Reader
3/4/23 9:26 p.m.

In reply to adam525i :

Thank you for the ideas! I cant add left to right capacity but i could add forward capacity i think but probably a lit less than a quart but thats not a bad thing. capacity is capacity. As far as horizontal baffles should i be concerned with oil's return path too much, or do a couple holes do?

Tazz9924
Tazz9924 New Reader
3/4/23 9:28 p.m.

In reply to Pete. (l33t FS) :

keeping it out of the cylinder heads isnt something i considered! i pondered the idea of a drain back line from the valve cover to the pan but i dont think the elevation is steep enough. 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
3/4/23 9:33 p.m.

In reply to Tazz9924 :

In my '88 Subaru, on 175 width all seasons, I could generate enough lateral G to get enough oil into one of the heads to cause the PCV system to suck it up and kill all the mosquitoes in the area.

I cannot imagine that EJ engines are significantly better than EA engines against this oil slosh, they just have better engineered PCV baffles.

Tazz9924
Tazz9924 New Reader
3/4/23 9:56 p.m.

In reply to Pete. (l33t FS) :

ive seen an ea generation subaru do unspeakable acts on the race track. glorious machines. 

This is true though and i will address it

adam525i
adam525i GRM+ Memberand Dork
3/5/23 8:47 a.m.

Those check balls are a cool idea, with the trap doors I left just a bit of clearance under them so they would never jam but I do worry that an impact to the pan bottom could bind them up, that would not be a problem with the balls. 

The factory pan in my case had a decent horizontal baffle so I mostly copied that. The general idea to me was to direct as much flow directly into the centre section by the pickup and to not impede the rest of the flow from making it's way down into the sump while also trying to keep it down there. It was a learning process though and I've made a few changes to the pan since I first modified it (making the baffle deeper, sealing it to the horizontal baffle better and that extra little baffle at the front of the pan for a specific issue with the M30 oil pump), I'm sure there are still improvements I can make but I'm hoping they aren't necessary.  

wspohn
wspohn SuperDork
3/5/23 12:04 p.m.

I have found horizontal sheets brazed or welded to the sides of the sump with a plunged hole just slightly bigger than the pickup works as well as the swinging door style, plus it let's zero oil up the sides of the crankcase once it is below the sump. Simpler to design and install, too.  That and an Accusump and you are good to go.  Yours sure looks pretty though!

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