Engine Bearing Failure
 

We don't want to hijack Toms engine thread so I figure we need to start one specific to this topic.

My comments, checking the good book it says that the filter will be bypassed above 23psi. Idle pressure is 14psi so in short 1,200 rpm and you have no filter as its bypassed.
Pump relief comes in at 85psi so we should have plenty of pressure.
My calcs say at 7,500 rpm the pump is pumping 84l per min.

A final comment thicker oil may raise increase oil pressure but this will reduce flow and if pressure goes over 85psi the oil will just go around the pump in a loop.

We need guages as Matt has suggested to know what is happening in the engine.
Tony

Re: Engine Bearing Failure
 

Thanks Tony,

Having now lost two big ends, one definitely heat related, and one of unknown, we are keen to chase some improved options now that we are pushing the motors more than Subaru intended.

It would also be helpful if the experienced folk offered some roadmaps for bottom ends. I know some generic stuff, but SVX specific (if you've got anything) would help.

Like...NA - 7000 rpm = do nothing
NA - 8000 rpm = light weight rods and good cast pistons
NA - 9000 rpm = etc etc etc

Anybody know the weight of the stock piston and rods?

Re: Engine Bearing Failure
 

Just sent Matt a text explaining his issue may have been cold oil. He told me the outside temp was -2 C. Remember he is not using a thermostate so the engine would remain cold. What I said to Matt was I have seen other engine have oil problems in cold weather.

The good book says below 0C to use 5W 30 oil.

This is of course is just a suggestion.

Tony

Re: Engine Bearing Failure
 

read this

http://www.circletrack.com/enginetec..._pressure.html

Re: Engine Bearing Failure
 

So basically Tony, is it healthy for the engine to constantly change oil grading during the year? I mean following weather temperature?

If the weather is variable between 0 and 35 degree during the year, shall we use one universal grade oil? or two grades at different stages?

Re: Engine Bearing Failure
 

That is pretty normal range so the good book says 10w30 were I am it gets really hot so I run 10W 40.

Re: Engine Bearing Failure
 

Centrifugal force increases with RPM and is an important consideration in respect of big end bearings. Think on this while examining the cross section and routing of the oil ways in the crankshaft. The length and cross section of passages leading outwards should equal those running inwards, so that there is a balance. However in any event, friction is increased due to substantial inertia and in particular, any abrupt changes in cross section result in increased resistance.

All in all this is probably the most critical section of engine in regards to oil flow/pressure, hence the first to give trouble. It must be remembered that the oil is a major and vital dissipator of localised heat, as well as being a lubricant. An added efficient oil cooler must surely be essential when the engine is being subject to above normal stresses.

Re: Engine Bearing Failure
 

One of the guys makes a real point I would never have considered. In short we set bearing clearance cold whic doesn't allow for when the bearings heat up and the clearance changes. Seems what Mike suggested was heading in the right direction (aim for 0.0018") it seems most of the engines chasing 8,000rpm run 0.003".

Here is the artical
http://speedtalk.com/forum/viewtopic...42ea3&start=15

Have a great day.
Tony

Re: Engine Bearing Failure
 

Good point Tony,

In my experience it has been normal to fit bearing used in racing applications with in excess of normal clearances, for the reason that the engine is going to be run at high speed without the run in period expected with a normal road car. In some ways not ideal, but necessary.

Re: Engine Bearing Failure
 

I was directed towards this thread via PM from Tony. I'll input my "thoughts" behind this and let you take them as needed.

There are many things I can add to this thread and I could sit here all night typing away but I'll hit off on some points that have been brought up first, let you ask questions as needed, and I'll answer as I see them here.

Aftermarket air oil cooler. I have been saying this for YEARS in the subaru community. These motors NEED and oil cooler, and no not that piece of garbage liquid cooler found on the EJ2-25 series motors. A good quality 10+ row air oil cooler is required; Setrab, Mocal, Modyne, etc, etc are all excellent manufactures of such heat exchangers and Bat Inc(www.batinc.net) is my wholesale supplier of all my oil cooler components(except setrab coolers). It is of utmost importance to keep oil temps in these motors below 110C. I've been running a "top mount" oil cooler on my motor since day one of the swap, and have logged oil temps between ~55-60C normal driving to about 85C running hard on a hot day. Dead cold, you can fire up the motor and the oil cooler will be hot to the touch long before the thermostat even opens to let coolant to the radiator, and this is not just on the EG33. Take that in for a bit of info.

Increased bearing clearances.......Increasing bearing clearances on race motors is nothing new. I do it myself on any motor I build that is destined for a life of track use. The increase oil film thickness works two fold in removing extra heat and also dampens the shock load of the combustion cycle better. It's best to stay within the high end of the max allowable spec, but everything is bearing and application specific and each builder has their own preferences and tricks. I have mine. However the oiling system must be up to the challenge to feed the motor in doing so. I will NOT run a subaru motor with increased bearing clearances without a 12mm oil pump at minimum. Period. The stock pumps lose the ability to flow enough oil volume at elevate rpms on clearanced motors as is, and cavitation compounds the effect. My preferred method is to dry sump the motors. Obviously this is a cost prohibitive method for most people and isn't the easiest thing to do.

For those with some pockets to dig into, I have performed some very elaborate case machining on EJ motors that reworks the oiling system path, most specifically related to a DS conversion but not all.

Cross drilling and modifying the crankshaft feed is also a highly recommended procedure. Although again, requiring an oiling system capable of the upkeep.


Big end distortion.......this is the #1 killer of high RPM motors, regardless of what people like to think. B.E.D. causes many things but the major thing is does is create localized bearing load and heat, caused by disrupting the oil flow around the bearing surface. If you can't control big end distortion you're just wasting your time and money in the build. If you don't get it under control, no amount of oiling, modifications, or supreme engine assembly will save your motor from becoming the next pile of parts in the corner of the garage. The motor must be built for the task at hand, and yeah it may not be cheap at all.

-Use proper grad fasteners. Any motor I build that's set for 8K+ rpms gets aged 625 rod bolts. If the customer doesn't want to pay for them, I don't build that motor. Period, done deal. Obviously not worth my time if they're dickering over an additional $350-$400 in parts in a multi-thousand dollar build. Those fasteners provide the required clamp load, but more importantly hold it at rpm. 99.99999% of the time rods don't fail from power, they fail from excessive rpm and fastener failure(either from distortion, or complete snap failure)

-Control the reciprocating weight. Weight is important down to the gram.

-Change the motor geometry to suit the intended purpose. If someone contracted me to build them an EG33 for high revs, you can bet I'd be building a long rod motor, possibly destroking it a slight bit as well with a welded/offset ground/nitrided crank.

If one can build 2.8L-3.6L flat six porsche motors to swing to 9k+ and last, the EG33 is not an impossible feat. It's just going to take someone with the money, or capabilities to do relatively free, to find the way.

Well it's 3am here and I've got to get some sleep. If my wording seems obscure above I blame it on the new asthma medication I'm on! haha:lol: I don't want to force my motor building techniques onto people, but if you have questions don't hesitate to ask. FWIW I may or may not have an EG33 sitting at the machine shop in pieces getting looked over for a build for some WRX here in the forseen future.....

Re: Engine Bearing Failure
 

Thanks for that.

Some things in there to think about for sure.

With your oil cooler, do you run a sandwich plate, or have you tapped into the pump correctly?

Have you ever considered shimming the factory oil pump?

thanks,
Matt

Re: Engine Bearing Failure
 

On non-dry sump motors, a sandwich plate is used. Thermostat is nice, but most of the time I run a non-thermostatic housing as I prefer 100% cooler flow. Oil can be "too cold" but you just have to pay attention to the climate and adjust things accordingly. If running a heavy weight oil, give it a few minutes to warm up, it's doesn't take long at all. Summer months in my car I'm running 15w-40, very hot months or track days I run 20w-50. Both non-synthetic(Rotella brand to be specific). During the winter months I drop to 5w-30 and cap the cooler duct 50%.

On DS cars I run the coolers inline between the pressure section and the motor(clean oil)

There's no way to tap the OE pumps without pressure loss(oil would flow directly from pressure to scavenge side of pump rotors), or without such extensive pump/timing cover modifications that you're pulling a stretch and might as well bite the bullet to go DS. in reality you need to run `10AN sized fittings, and there not lot of room behind the covers to

Shimming the pump is a bandaid. You can shim the pump till you turn blue but you're still working with stock gerotor flow. You have to increase the pump's displacement per rev to make a difference. Thicker gerotors do that(I have yet to tear apart an EG33 pump for specs, it's sitting on my bench to do so right now. Maybe i'll do that today.

-Adam

Re: Engine Bearing Failure
 

Adam, can you please share some pictures of the setup? You obviously tapped the block from somewhere I am not mistaken...

Re: Engine Bearing Failure
 

yes,will do. Didn't tap the block, used sandwich plate.

I'll take a few pics tonight.

Re: Engine Bearing Failure
 

Cool thanks :)