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Old 08-05-2006, 07:41 PM   #1
bugeyes
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Question Downfalls of the oem oiling system for high rpm engines?

It is a widely spoken "fact" that the oem oiling system will not handle sustained high rpms.
As I start to get the bits together for my new 2.5 build I am questioning why the engine had this reputation and how to overcome it. We see engine places such as axis and crawford modifying oil supply holes in the crankshafts to improve oil supply to the rod journals but why is this being done? I mean I have had many Nissan turbo engines that have run new standard oil pumps with non modified cranks that have never shown to have oil supply problems. The subaru setup runs grooved bearings, cross drilled crank and champhered oil holes and reasonably high oil pressure, it looks to be a good setup.

What is the cause of the oil supply problems then........
Does the pump lack volume capacity?
Are the engine tolerances too tight for high rpm use?
Does the oil system lack overall pressure?
Poor oil drainage causing the sump to run low and cause oil pickup problems?

I had a quick look at the oil pump Cosworth offers and was dissapointed to see it only a standard pump that has been given a flow port job through the passages, the actual pump component is the same, frankly I was expecting a larger pump gear to be fitted.

Could we locate the exact cause of the oiling problem so we can discuss the best way to overcome it........
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Old 08-05-2006, 09:02 PM   #2
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I've been leaning towards the belief that it has more to do with the lack of balancing in Subaru motors. No engine builders for Subaru can completely balance the rotational and reciprocal mass as they would in an inline engine because there's no room for large enough counterweights. I have a hunch that extra oiling holes are a band-aid fix for a problem which has little to do with the oiling itself. Poor balancing could certainly cause enough twisting on the crank to make the oil-film fail.

But this is just a hunch ...
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Old 08-05-2006, 11:25 PM   #3
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this has been a recent discussion at our shop and well, imagine that...a thread starts on it
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Old 08-06-2006, 01:24 AM   #4
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Quote:
Originally Posted by SaabTuner
I've been leaning towards the belief that it has more to do with the lack of balancing in Subaru motors. No engine builders for Subaru can completely balance the rotational and reciprocal mass as they would in an inline engine because there's no room for large enough counterweights. I have a hunch that extra oiling holes are a band-aid fix for a problem which has little to do with the oiling itself. Poor balancing could certainly cause enough twisting on the crank to make the oil-film fail.

But this is just a hunch ...
i agree with this theory, i rarely see these engines getting a proper balancing
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Old 08-06-2006, 03:38 AM   #5
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If it was a balancing issue (and I'm not saying its not), why do the engine builder which balance their engines still modify the cranks?

I recently started a thread based on balancing of subaru crankshafts. The fact is the subaru crank cannot accomodate counterweights large enough to cancel out the weight of the rod/piston. Therefore the crankshaft is considered to be a "coupled" type crank which relies on the two adjacent journal loads to cancel each other out. What I am saying is the 2 front cylinders cancel each other out due to them being 180 degrees apart on the crank. This puts extra load on the main journal between them.

What I am getting to here is if you fit heavy rods and heavy pistons you are increasing the load through the crank which would increase any amount of twisting and hence increase the chance of oil failure (if this theory is correct??).

Does anyone know the statistics of what typically fails, is it mains or rod journals and is it any journal in particular?
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Old 08-06-2006, 05:56 AM   #6
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Quote:
What is the cause of the oil supply problems then........
Does the pump lack volume capacity?
Are the engine tolerances too tight for high rpm use?
Does the oil system lack overall pressure?
Poor oil drainage causing the sump to run low and cause oil pickup problems?
Pump volume not a big issue, even in the big block V-8 world they are learning that stock oil pumps usually deliver plenty of flow. Over sized high flow pumps actually can be worse than stock pumps. They use up power that could best be delivered to the crank shaft. They heat the oil more than the stock pump, as they are doing more work on the oil, They tend to agrivate oil drain back problems, as they do a much better job of emptying the oil pan and do nothing for oil drain back.

The engine tolerances are a bit tight for sustained high rpm operation. Race motor builders frequently open up bearing clearences to account for the increased heating and higher loadings seen in high rpm operation. Running too tight of a clearence is a one way ticket to an engine rebuild.

The stock oil pump pressure in the turbo engine is adequate up to about 8000 rpm, but due to the use of a cross drilled crank, oiling problems begin to crop up at that rpm due to problems in delivering adequate oil flow against the building centrifugal force which is trying to throw the oil out of the crank journals. When the counter pressure developed by the centrifugal forces equals the supplied oil pressure oil flow shuts off. Also the high centrifugal forces in a cross drilled crank journal tends to induce bubble formation in the oil at the center of the journal (where the oil feed hole to the connecting rod comes in) and this delivers aerated oil to the con rod.

Poor oil drain back to the sump is very high on the list of problems that need to be addressed. The Stock oil supply routing can pump large quantities of oil into the cylinder head and the oil drain back path is not designed to "assist" oil return to the pan. Using thick heavy weight oil to "protect the bearings under high load" actually makes this problem worse as it drains back slower than lighter oils and takes longer to get rid of air bubbles entrained in the oil.

Balancing is helpful but not the primary issue.

Detail work on the oil pump passages (and engine oil gallery passages) is how the high end racing engine builders keep adequate oil flow without jacking the oil pressure to the moon. Cosworth knows what their doing.

The secret to keeping an engine alive at sustained high rpm is not one magic component it is a lot little details and detail work on the oil system.

Part of the problem is that most folks are measuring their oil pressure at the wrong location. They are measuring it near the oil pump, oil filter, or the main oil pressure switch which is just past the pump.

In a racing engine you want to measure oil pressure at the farthest point of the oil delivery system. On our engines the oil supply to the heads/cams and the turbo are at the far end of the delivery system. It would take some experimentation to find the best possible tap point for measuring the oil pressure, but the rear of the cam galleries, or the turbo oil supply would be the two places I would look at first. By the time the oil OEM warning light comes on as system oil pressure coming out of the oil pump drops below 2.1 psi (the set point for the pressure switch) you essentially have no oil pressure in the distant bearings. It is basically a "you just killed your engine light"


My suggestions for keeping a Subaru engine alive at high rpm.

Don't run a heavier oil than you need to.
Add an oil cooler (which adds to the oil system supply volume) and helps control oil temp.
Put a second oil pressure switch (and or gauge) and light mounted off the rear of the head oil galleries set at 15 psi or so.
Higher capacity oil pan, or an external reservoir such as an Accusump.
Run a crankshaft such as the STi drilling pattern or one of the after market designs that elminates the OEM cross drilled main design.
Do some detail work on the oil supply passages on the oil pump and the engine oil supply galleries.
Do some detail work on the cylinder heads and the oil drain back path to improve oil return to the pan. (paint the head surface in the valve cover with an oil shedding coating to speed oil return).
Use properly clearenced, high quality rods that are better able to keep the big end round under high enertial loadings at high rpm.
Get an engine builder that knows how to clearence the rods for a high rpm engine.
Properly baffel the oil pickup, and control its pickup to pan clearence.
Install a dry sump system if your serious about high rpm operation.
Understand how you are loading the engine and how that changes oil supply problems (ie a drag racer will have different needs than a road racer).

Larry

Last edited by hotrod; 08-06-2006 at 06:03 AM.
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Old 08-06-2006, 06:57 AM   #7
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Interesting points you make. One thing you touched on I want to take further.

The oem cross drilled crank.
It was always my understanding that the requirement for a cross drilled crank was on engines that only had half groove main bearings. I think an example of this would be some straight six engines. In these engines the lower half of the bearing cap had no groove. This was to provide maximum bearing surface area against the combustion load pressing on it from above. The top half of the bearing had a groove and in order to keep oil supply to the rod journals the crank had to be cross drilled.
Now on our subaru engines we dont use half groove bearings due to the boxer layout, however even though we have virtually full groove bearings (the rear thrust bearing is in fact a full groove all the way around), we also have a cross drilled crank.
When I mentioned this to my hard core "I'll never run anything but a chevy" friend he thought it was a peculiar setup.

I just did an internet search and found numerous accounts and several tech articles on how cross drilling has great potential to damage rod bearings. After reading several of these I'm and pretty much convinced this is our problem. Subaru's tend to kill rod bearings, not main bearings. We have an odd setup that is ok whilst the engine runs at reasonable speeds but will starve the rod journals at high rpms.
The typical solution is high oil pressure but this has other downfalls, what we really need is a 2 stage oil pump. A pump that runs at oem oil pressure at revs less than 5500 and boosts the pressure up over 5500 so it ensures we overcome the centrifugal force that work against our oil flow at high rpms through the crank.

Last edited by bugeyes; 08-06-2006 at 08:29 AM.
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Old 08-06-2006, 03:08 PM   #8
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Quote:
After reading several of these I'm and pretty much convinced this is our problem. Subaru's tend to kill rod bearings, not main bearings. We have an odd setup that is ok whilst the engine runs at reasonable speeds but will starve the rod journals at high rpms.
Correct, the OEM oil system is designed for long engine life at moderate rpm, that is why the Subaru STi crank (2.0 L) has a different drilling pattern to it. Cross drilling was originally used in diesel engines as I understand it, and gives great oiling and very long bearing life at moderate engine rpms, but basically shuts off oil flow when engine rpm hits a critical rpm where centrifugal force in the crank main oil gallery equals engine supply oil pressure.

Changing the crank drilling pattern to one that is more friendly to high rpm is less complicated than a high tech oil pump system.

In my opinion the OEM oil clearances on the rods are a bit tight. The OEM clearence is .0008 - .0018 with .0020 being the max limit on a 1.8891 - 1.8898 crank pin.

A rule of thumb for connecting rod oil clearance for performance engines is .0012 clearance per inch of crank pin diameter. Using that rule on the max allowable crankpin size of 1.8898 we get a suggested clearance of .00267 clearance on the rod journals. If a person buys an OEM short block and it happens to be a tight one fitted at .0008 rod clearance, you are way tight on oil clearance and at high rpm as the connecting rod pinches in at the top of the stroke as it sees maximum loading you will squeeze out all your oil clearance.

If I were building an engine today I would fit the rods at OEM max oil clearance or even slightly larger if I was going to be running serious rpm.

You also need to measure your actual rod big end diameters and standardize them to a uniform standard. For example John Lingenfelter, has two standard rod sizes he used on the Chevy V-8 engines he built. The OEM size spec for the small journal rod (nominal 2.00 diameter) was 2.1247 - 2.1252, he spec'd all his rods for this journal size at exactly 2.1250. On the large end rods (nominal 2.100 diameter) the allowable range was 2.2247 - 2.2252 from the factory, he spec'd these rods at 2.2250.

Note he did not spec a range of rod sizes there was just one rod size -- it is this level of detail that made him one of the premier engine builders in the industry.

Now for comparison, the OEM oil clearance spec on the 2.100 rod journal size for the Chevy 400 was .0013- .0035. (this equals .000619 / inch of crank pin diameter to .001666/inch of crank pin diameter.)

If you scale those clearences down to a 1.8898 crank pin used in the Subaru, our clearence which would be equivalent to the OEM Chevy clearence would be -- .00169 -- .00315 compared to our stock clearances of .0008 - .0018 .


In the for what it is worth department, the big name engine builders for high power V-8 engines tend to use oil clearances of about .003 - .0035 on the rods on their high rpm race engines. Any tighter than that and they do not live. In short they run max allowable or very slightly larger oil clearances to allow for the stresses in a high rpm environment.

It seems to me on a street build for a high performance engine a rod clearence of .0020 would be sensible, and for a no holds barred 9000 rpm engine build I would probably open them up a tad more to .0025 - .0030 on the Subaru rod journal size.

Disclaimer -- this is just my educated guess based on my experience, not a gurantee that this is the best possible setup. Consider this only with careful dimensional control on rod big end size, and crank journal size and at your own risk.

Larry

Last edited by hotrod; 08-06-2006 at 03:15 PM.
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Old 08-06-2006, 07:28 PM   #9
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Hotrod, I totally agree with your thoughts on the bearing clearances and I have thought a lot on this subject.
The main sticking point for me is how much does the block expand? Being alloy they tend to be quite tight when cold (never rev-up a cold suby engine, your playing with fire).

I normally plastigauge all my bearing journals prior to final assembly and on my last engine spoke with the crankshaft grinder which does the cranks for Rigoli racing. He told me they spec their bearings to 0.002" to 0.0025" clearance. I have setup my current engine with 0.0015" to 0.002" which makes it just that fraction "looser". As I have cams my engine spins up to 8k no problems but I always have the fear of the oiling system bug in the back of my mind.

I have a couple of subaru crankshafts lying about and I'll give the drilling pattern a carefull look at today. You mentioned the sti 2.0 crank had different oiling pattern, do you have more details on this? I would really love to see what the suby engineers tried.

Would anyone have any details on the sti 2.0 crank drilling pattern?

One other thing that I generally dont like is the shape of the oil hole reliefs on the surface of the journal. It has been proven the lead-in type of relief in the direction of rotation is very successful design for high rpms. Unfortunately, we are unable to adapt this method (unless we weld up the back half of the relief), thanks to the oem relief. I think this would be worthy modification. If you guys go to Crawfords website and look at the pics of his billet cranks you will notice that is exacty what they have done.

Whilst the subaru crankshaft is a clever piece of engineering it leaves a lot to be desired from a purely performance perspective.......
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Old 08-06-2006, 08:14 PM   #10
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Quote:
Originally Posted by bugeyes
I have a couple of subaru crankshafts lying about and I'll give the drilling pattern a carefull look at today. You mentioned the sti 2.0 crank had different oiling pattern, do you have more details on this? I would really love to see what the suby engineers tried.

Would anyone have any details on the sti 2.0 crank drilling pattern?
can you post some pictures of the crank? do you have anything to put through the 'cross drilled' hole and take pictures of this?
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Old 08-06-2006, 08:23 PM   #11
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http://forums.nasioc.com/forums/show...ight=jdm+cross


I wanted to post that link because on page 2 it has pictures of a 2.0l crankshaft....thanks to Hotrod. that thread is a good read.
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Old 08-06-2006, 08:47 PM   #12
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Beat me too it, that thread shows some of the differences, I know the 2.0L STi crank is drilled differently but so far have not held one in my hands so cannot comment on them from first person knowledge. I assume they used one of the drilling styles where the oil feed to the connecting rod journal intesects the main drilling near the surface to eliminate the issue with centrifugal force as much as you can.


On aluminum blocks thier higher expansion rates actually open up the bearing clearances on the mains as they get hotter, so the mains should not be much of a problem.

On the rods the issue is one of the detail of the construction of the rod itself and how strong it is.

The highest load the connecting rod big end sees is not on the power stroke it is at TDC as the intake stroke starts. Especially on throttle lift engine braking, where intake manifold vacuum is trying to pull up on the piston as the crank is trying to pull it down.

At TDC the load is upward (toward the piston) as the recipocating assembly changes direction and this pull tends to try to stretch the big end of the rod into an oval shape. Depending on how rigid the rod is (and how high an rpm your turning) this can pinch in the rod on the rod journal at the parting line. If it pinches in enough the journal grabs the bearing and instant engine salad follows immediately after as the big end of the rod gets ripped off as it tries to twist with the crank pin.

This is why engine bearings have extra clearence on the bearings at the parting line, but sometimes in high rpm usage this extra clearence is not enough. When that happens you have to open up the clearence, or get a rod that is stiffer on the big end so it can better resist the tendency to pinch in on the crank pin.

Larry
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Old 08-06-2006, 09:23 PM   #13
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Quote:
Originally Posted by bugeyes
If it was a balancing issue (and I'm not saying its not), why do the engine builder which balance their engines still modify the cranks?

I recently started a thread based on balancing of subaru crankshafts. The fact is the subaru crank cannot accomodate counterweights large enough to cancel out the weight of the rod/piston. Therefore the crankshaft is considered to be a "coupled" type crank which relies on the two adjacent journal loads to cancel each other out. What I am saying is the 2 front cylinders cancel each other out due to them being 180 degrees apart on the crank. This puts extra load on the main journal between them.

What I am getting to here is if you fit heavy rods and heavy pistons you are increasing the load through the crank which would increase any amount of twisting and hence increase the chance of oil failure (if this theory is correct??).
Yeah, I posted in that thread. The engine is "considered" a coupled type, but not such crank truly exists. I wouldn't be suprised if heavier rods/pistons did increase the chance of failure, but they may not necessarily do so.

Quote:
Originally Posted by hotrod
Balancing is helpful but not the primary issue.
Maybe, maybe not. But the inadequacy of the Subaru balancing system is going to send some very strong first-order vibrations all up and down the rotating and reciprocating mass in the engine. That could easily wreak havvoc on oil-film stability and cause significant fretting wear. Just the second-order vibrations inherant to inline-4 engines can cause problems with the oil film on the cyllinder wall and create issues with fretting wear.

I still think there's a strong possibility that, were the Subaru crank capable of being fully balanced, you wouldn't need to modify the oiling system until a significantly higher RPM. But, it is just a hunch and, since it isn't possible to fully balance a Subaru crank due to space restrictions, we'll probably never know.

-Adrian
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Old 08-06-2006, 09:24 PM   #14
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Quote:
Originally Posted by hotrod
The highest load the connecting rod big end sees is not on the power stroke it is at TDC as the intake stroke starts. Especially on throttle lift engine braking, where intake manifold vacuum is trying to pull up on the piston as the crank is trying to pull it down.

At TDC the load is upward (toward the piston) as the recipocating assembly changes direction and this pull tends to try to stretch the big end of the rod into an oval shape.

Larry
really? Ive never thought of that....huh. i always assumed the highest load was on the power stroke trying to 'compress' the rod.
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Old 08-06-2006, 09:45 PM   #15
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I've been at the computer for a while now and have just applied everything I have learned.
I had a EJ20 standard crankshaft to spare so I have modified the front main journal to see if its possible. Here is what I tried to do-

1- Single oil supply hole on main journal which would be used with a full groove main bearing shells.
2- Hole drilled so oil enters the oil hole in direction of rotation, this makes oil pickup easier (doesn't have to make a 90 degree turn in order to enter the crank)
3- back side of oem hole relief welded up
4- Oil hole does not pass through the centre of the crank therefore reducing the effects of centrifugal force acting against the oil flow
5- Oil lead in groove in direction of rotation, this gives the oil time to enter the groove before being scooped up by the hole.
6- Oil supply hole same diameter as oem 5.5mm.
7- New oil hole drilled to intersect the original hole approximately at the web.
8- Pressed in a steel pin to block off the original cross drilled oil hole.

I think this proves it is possible, I used one of the old hole positions so I didnt have to drill the bearing surface with a new hole.
Looking at this design I feel its a much better option for high rpms.

Whats your opinions on this design -
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Old 08-06-2006, 09:58 PM   #16
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Quote:
Originally Posted by bugeyes
1- Single oil supply hole on main journal which would be used with a full groove main bearing shells.
-single groove seems to be the way to go for high rpm applications
2- Hole drilled so oil enters the oil hole in direction of rotation, this makes oil pickup easier (doesn't have to make a 90 degree turn in order to enter the crank)
-is the hole 90* to the bearing surface? pardon...i havent seen a suby crank.
3- back side of oem hole relief welded up
-could you take pics or explain....i dont know what this is?
4- Oil hole does not pass through the centre of the crank therefore reducing the effects of centrifugal force acting against the oil flow
-where does it go if it doesnt go through the center of the crank? i dont follow. please excuse me...im trying to see/learn.
5- Oil lead in groove in direction of rotation, this gives the oil time to enter the groove before being scooped up by the hole.
-makes perfect sense!
6- Oil supply hole same diameter as oem 5.5mm.
7- New oil hole drilled to intersect the original hole approximately at the web.
-again...dont know exactly what you're talking about. where is 'at the web'?
8- Pressed in a steel pin to block off the original cross drilled oil hole.
-just dont want the pin to be too heavy.

I think this proves it is possible, I used one of the old hole positions so I didnt have to drill the bearing surface with a new hole.
Looking at this design I feel its a much better option for high rpms.

Whats your opinions on this design
^^^i like the design. got any more pics of the crank?
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Old 08-06-2006, 10:11 PM   #17
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Modaddict, let me clarify a few things, I'll refer back to original points-

#2- the oem oil hole is drilled straight across the journal. This means the oil must make a 90 degree turn in order to enter the oil hole. As you can see in my pic with the rod in the hole. I have angled the entry hole so the oil only needs to make a 50? degree turn to enter the crank. This along with some neat champhering should greatly help pick up of oil at high rpms.

#3- The oem oil hole has a lead in at both sides of the oil hole. In my modified example you can see there is a lead-in taper so the oil get "scooped" up. The subaru crank has this standard (although much smaller), but it also has it on the other side of the hole so it sort of defeats the purpose. So the oem crank has a lead-in and a lead-out shape. Not a good design for good oil pickup.

#4. This can be difficult to explain.The standand oil hole is drilled so it meets the cross drilling at the centre of the main journal. What I have done is drilled the hole at an angle so it no longer passes through the centre of the main journal. The new hole is at an angle and it meets the original passage at about where the crank web is between the two journals. Look at it this way. Originally the oil had to make a 90 degree turn to enter the crank, then at the middle of the main journal make another 90degree turn to follow the passage to the rod journal. My design is a hole directly from the main journal surface to the original passage half way to the rod journal. This means the oil has a much easier path. The new hole is off to the side from center, this is a proven design as used on high perf chev cranks. I hope that explains it.

#8 the pin weight is not an issue. It it central to the crank so it wont affect balance. It really is just a steel rod 5.5mm diameter and 60mm long. Its only there to block the original cross drilling hole.
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Old 08-06-2006, 11:23 PM   #18
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Very interesting, I'm sure one of the drilling patterns common to other performance engines will be an improvement. Unfortunately it is tough to do testing with out actually spinning an engine fast enough to scuff the bearings to find out if you improved things much.

I would be very interested to see what sort of experience you see with those modifications.

I also favor the single entry style oil hole. The Subaru bearing is nearly a 360 oil design as it has a full oil groove behind the bearing shell in the mains, and feeds the oil through multiple oil holes so I'm not sure a true grooved shell would be necessary to benefit from the changes.

If I understand you correctly you appear to have created a "V" drill pattern with your modifications so the runner that carries oil from the main to the rod crank pin picks up the oil near the surface of the journal.

Larry
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Old 08-07-2006, 12:45 AM   #19
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Quote:
Originally Posted by hotrod
If I understand you correctly you appear to have created a "V" drill pattern with your modifications so the runner that carries oil from the main to the rod crank pin picks up the oil near the surface of the journal.
Yep, by having the oil passage like this it reduces resistance in flow in getting the oil to the pin journal. The other benfits being the hole is angled so it picks up oil easier and finally the reduction of centrifugal force acting on the oil flow.

I will be applying this oiling system to my 2.5L crank. The example in the pics was a rough test to see if it was possible which I have proven it is. I think with more time spent doing the job properly I should be able to come up with a very neat setup.
What I took pics of took me about half an hour to throw together and I only used basic hand held tools. I intend to do the 2.5 crank using a mill so I can accurately locate the drilling and improve on the angles.
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Old 08-07-2006, 01:48 AM   #20
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Then are you going to buzz it up to 12 grand and tell us when it blows up

Larry
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Old 08-07-2006, 04:28 PM   #21
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I have a picture of the drilling modification. I'll post it later today. If it works its becuase oil is being diverted down the extra hole in conjunction with the centrifugal force that is on it, instead of against it. Seems like it might help, but I think it's really hard to say. I'd rather see a non-cross-drilled crank where the oil is picked up from a central oiling bore that runs the length of the crank, or something like that.
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Old 08-07-2006, 05:13 PM   #22
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Quote:
Originally Posted by bugeyes
I recently started a thread based on balancing of subaru crankshafts. The fact is the subaru crank cannot accomodate counterweights large enough to cancel out the weight of the rod/piston. Therefore the crankshaft is considered to be a "coupled" type crank which relies on the two adjacent journal loads to cancel each other out. What I am saying is the 2 front cylinders cancel each other out due to them being 180 degrees apart on the crank. This puts extra load on the main journal between them.

What I am getting to here is if you fit heavy rods and heavy pistons you are increasing the load through the crank which would increase any amount of twisting and hence increase the chance of oil failure (if this theory is correct??).
making a good reason to choose piston size (for CFM: RPM differences between smaller and larger displacement) and titanium rods a good call
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Old 08-07-2006, 05:20 PM   #23
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Quote:
Originally Posted by SaabTuner
Yeah, I posted in that thread. The engine is "considered" a coupled type, but not such crank truly exists. I wouldn't be suprised if heavier rods/pistons did increase the chance of failure, but they may not necessarily do so.
add to that momentum of the rod and piston as the forces exerted are related to speed...
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Old 08-12-2006, 08:44 PM   #24
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Something to think about, the main shuts oil off to pins 1,2,3 at TDC on all 2.5's and non sti 2.0lts.

Mains that supply 1,2,3 pins, the main bearings are not full groove.

Pin oil holes are in the wrong spot too.
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Old 08-14-2006, 01:02 AM   #25
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Quote:
Originally Posted by MSR
Something to think about, the main shuts oil off to pins 1,2,3 at TDC on all 2.5's and non sti 2.0lts.

Mains that supply 1,2,3 pins, the main bearings are not full groove.

Pin oil holes are in the wrong spot too.
The rear main bearing is a full groove, the front and center are not. Yes the oil flow shuts off the rod journals 1,2,3 at TDC.

I dont beleive the pin hole position is causing oil starvation. The oil isnt getting to the rod journal because of the crappy cross drilled mains.
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