masterx81

iTrader: (4)

Hi! I'm doing some sort of study on the subby oiling system, and someone, please, have an open ej20 engine block to measure the restrictions that are found on the bottom of the oil holes that are feeding the main bearings?
They can be measured with some drill bits...
Would be nice to have the measures of a closed deck block (with oil squirters) vs an open deck....

Really thanks!!!

masterx81

iTrader: (4)

No one have, please, an opened ej20 engine to take this measurements?
Thanks!

masterx81

iTrader: (4)

Up

JohnD

iTrader: (5)

I can't help with your request but if at the end of your project you could post up your findings and conclusions, there would be an interested audience on here! The reasons for bearing failures on this engine is quite a contentious issue!

JohnD

masterx81

iTrader: (4)

From what i've understood (with some people on nasioc), a thouble in the subaru design is that the rods 1 and 4 are feeded by 1 and 5 main bearings (one for each), but rods 2 and 3 are feeded from the same n°3 main bearing (the flow is split inside the crankshaft).
They have tryied to balance the oil flow by using some restrictions on the galleries. This will reduce flow and pressure on some bearings: 1, 3 and 5 more flow (maybe 3 more flow than 1 and 5, but i need the dimension of the restrictions), and 2 and 4 less flow than the others. In this way if on the main gallery we have 80 psi of oil pressure, on bearings 1 and 5 we may have 50psi, on 3 70psi and on 2 and 4 30 psi (random numbers, only for example). In this way can be used a lower flow oil pump (less power loss), the rod bearings under most of the time are getting equal pressure, and so on.
But as the revs goes higher, the balance can be lost. Also changing flow at the bearings (increasing oil pressure or using greater bearing clearances) or oil density can change the balance.
I'm trying to figure if the problem can be moved far away by removing all the restrictions, with an uprated oil pump and using a relief valve at the end of the main galleries instead of the one integrated in the oil pump. In this way MAYBE we can get more stable oil pressure at the main bearings, and the same pressure will be diveded by the bearings. But the problem can't be totally eliminated because the rods 2 and 3 are always splitting they flow sent by the main #3...
I've not found this type of restriction in any other engine that i've dismantled, because other car makers had used 5 main bearings of the same and every rod bearing is feeded by only one main bearing. Subaru have used 2 and 4 smaller bearings maybe for shortening the crankshaft, and that main bearings wasn't good anymore for feeding the rod bearings. The 2 smaller main bearings actually can eat also less power than 2 full size bearings.

As now i've already drilled though the restrictions, without measuring the before, so i need the measures for doing a more accurte analysis on the oil flow distribution, and in case, reapply the restrictions (i don't like too much the ieda of destroying my newly built forged engine for R&D, if actually i'm not 100% confident on the mod....)

That's why would be nice to know if there is difference from oil squirted blocks vs open deck blocks, as the oil squirted block have the squirters feeded by n° 2 and 4 main bearings, so i'd suppose that the restrictions here must be a bit bigger....

masterx81

iTrader: (4)

Up... No one with an opened block under the hands?

MOTORS S GT

iTrader: (2)

The block measured is 2.0 open deck, Main No1 = 5.5mm, 2 = 3.5mm 3 = 6.4mm 4 = 3.5mm 5 = 5.4mm.
A 2.0 semi closed is as above also.
I have some EJ257 blocks from 08 STI's i will check if they are the same, & let you know.

masterx81

iTrader: (4)

Oh, wow, you have confirmed all my suppositions!!!
This is what can be called a 'compromise'...
And maybe is why the subby oiling system isn't that good, and we have a lot of trashed rod bearings in the garage...
There is a chance that #1 and #5 main bearings have the same measure and that the 0.1 difference is a measuring error?
I was excepting if they wasn't the same that #1 main bearing will have more restriction than the #5, because at the bearing #5 we have a bit less pressure due the 'leak' from the previous bearings....
Really thanks for the help!!!

merlin24

iTrader: (1)

You also have to remember that the main bearings on journals 1,3+5 are fed from the oil gallery on the R/H block half and journal 2+4 are fed from the oil gallery on the L/H block half.

Mick

masterx81

iTrader: (4)

As now i don't have the blocks under the hands, but if i well remember they aren't connected in this way. are something like 1+2, 3+4+5, or
2+3 and 1+4+5 or similar. 2 adiacent bearings are feeded by the 'other half' of the block (i don't remember if left or right), that have also the main gallery much shorter.

masterx81

iTrader: (4)

-EDIT- all wrong...
The flow and pressure flow will be more uniform to the bearings...

masterx81

iTrader: (4)

Any other confirmation on the measurements? Especially on the difference from main 1 and 5?
Thanks!

masterx81

iTrader: (4)

I've checked, the two oiling galleries are feeding one 1+4+5 main bearings, and the other side feeds 2 + 3. so it's quite strange the 5.5/5.4mm difference

masterx81

iTrader: (4)

Still searching confirmation and measurements of a closed deck block... Thanks!

D1CCY

Fascinating. I've wondered in the past about the common oil gallery. Didn't realise that Subaru had balanced the flow with restrictions. This raises what happens with different oil viscosities, higher than recommended may adversly effect flow in some areas.

masterx81

iTrader: (4)

Yes, and also different pressures or loosen bearings play can 'unbalance' the equilibrium established by those restrictors...
It's a compromise for the ultra-short design of the subby crank, and the split flow between 2/3 rods.

It's interesting how cosworth have made theyr cranks:
Seem that they have drilled through rod 1 to main 2 (normally used only for supporting the crank or feeding the oil squirters) to rod 2 and rod 4 to main 4 (same as main 2) to rod 3. I don't fully understand how this works, as with the restrictors in place main 2 and 4 have much less pressure then the others...

masterx81

iTrader: (4)

So no one with a cdb under the hands?

MOTORS S GT

iTrader: (2)

I have meassured a 08 EJ257 semi closed block, a EJ20 semi closed & a EJ255 open deck block & there as above within + or - 0.1mm.
But i must say the restriction drilling centre line is never the same from block to block.

masterx81

iTrader: (4)

Really thanks for the measurements! Your help is much appreciated! At least, to try to understand this strange oiling system (and maybe find a way to made it a bit better)
So with a measurement tollerance of 0.1mm the 5.4mm one can be 5.5mm? As i can't explain that difference from the main n°1...
There was consistency between the dimensions of the holes, or there was some tollerance? As other builders have noticed that some block are more prone to spun bearings that others, but they not know if can be tollerances on the bearings (especially on rods 2/3, that split the flow) or elsewhere.
There was consistency on the height of the restricted holes? What's that height?
Maybe the centerline misalignment was due to production tollerances, but it's quite strange, as i'd suppose that both holes are made in the same machining process...

Now would be nice to find a cdb to see if the 2 and 4 mains have different dimensions as excepted. And maybe a spec c 2.0 engine, to see if the change was only on the crank (that engine have a different drilling scheme, with timed holes on the mains) or also on the restrictions...

Still, really thanks for your time!

masterx81

iTrader: (4)

I've buyed some small bore gauges and i've measured an ej20 v2 1997 engine, with the following results:
main 1: 5.49mm
main 2: 3.46mm
main 3: 6.23mm
main 4: 3.47mm
main 5: 5.30mm

Next maybe i can put my hands on a cdb

Jamz_

iTrader: (12)

Interesting read this like... gonna keep my eye on this and see if you find anyway to make the problem a little better

masterx81

iTrader: (4)

I suppose that using a good baffled sump (absolutely no oil starvation, or a dry sump), with good quantity of oil, right oil visscosity and temperature, control with accuracy the clearances (main oem, and rod on the loose side, for have some more flow to remove heat from the bearing) and using some serious bearings can eliminate at least 90% of the common bearing failures. If they fail also with all this 'common problems' sorted, so wolud be useful to try, for example, the full flow oiling scheme of cosworth drilling the oem crankshaft...
For my first engine, i will try to optimize all that parameters (with much probability i'll go on the dry sump route). If the bearing survives in this way, there's no need for modifying the oem oiling scheme (in any case, the flow division between rod bearing 2 and 3 isn't a good compromise...)