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Old 06-17-2009, 06:46 PM   #326
HamFist
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That makes sense, even if it is OT. Thank you.
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Old 06-19-2009, 11:14 AM   #327
hotrod
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Quote:
Hotrod - What oil pan were you using? The STI or the WRX pan?
Stock oilpan (2002 wrx). Engine itself was bone stock in all regards.

Larry
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Old 07-09-2010, 06:56 AM   #328
masterx81
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Sorry for bring up this really interesting one year old reading...
Imho, this is what's wrong on the subby oiling system:
-Narrow bearings
-split flow between rod #2 and #3, feeded by the same main #3 (with restrictions on the mains to balance flow)
-Quite tight oem clearances
-suffers a lot of oil starvation

What we can do to made it better:
-Use top quality oil, with the right grade, right temps, not areated, etc
-increase bearing clearances (increase flow)
-increase a bit oil pressure
-avoid oil stavation at any cost...

I not see cross drilling a bad thing (as i've read on this long and interesting thread). It increase flow at the rod bearings. It's still true true that not slove the centrifugal force problem, but you forgot that while the 52mm bearing (from the center 26mm) it's trying to 'push' away the oil that it's entering in ressure in the pin itself, on the other side there is a column of oil of half stroke (37.5mm for the 75mm crank) that it's subjected to more centrifugal force (due to the more distance from the center of rotation). So actually the oil in the center of the crank is under a bit of vacuum. On the main there is oil pressure that try to push the oil in, on the rod side there is the bearing that restrict the oil exiting.
Seem that the double drilled spec c crank it's less prone to spun bearings, so adding more flow the the rod bearings seem help a bit. It's a bend aid fix, but if it works...
It's curious that on the spec c crank the drillings are 45 off phase from the old drillings, maybe it's made for avoid that a drilling goes straight in the gallery that then goes at the rod bearing?

There are 79mm cranks made with the spec c drilling pattern?
Else, will be possible to plug the stock drilling and cross drill it like the spec c rank? Maybe 3 through holes ewaks the crank too much...
And leaving the stock drillings and made the other 90 drilling? All the holes will be out of phase by 45 vs the spec c crank...
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Old 07-09-2010, 07:01 PM   #329
charliew
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with restrictions on the mains to balance flow

It's been awhile since I looked at the case gallerys but I don't remember the restrictions you are talking about. I sorta remember the #3 main might have had a bigger gallery or thats was something I was going to try next on one of my projects. Wittmer25 has a 12mm pump thats been cleaned up along with the gallery to and from the pump with a external adjustable bypass added at the filter adapter. It is adjusted to by pass through a 3/8 id line. It has about 100 psi at 7k hot. It has hit 9k on a missed 5th shift and so far seems ok with 5-30 pennsoil syn. it also has a 8qt pan though. The oil does run about 230-240 at wot on a 100 f hot dayand only about 15psi at 800rpms idle but it jumps to 40psi at 2500. It's still probably bypassing too much in the pump. It's a 2.5 sti with stock clearances on the bearings.

In my opinion I think if the oil is the right viscosity for the temp of the motor, is kept good, not run diluted, and topped off the sti motor will survive as long as it is not revved past 8k. I also think it could be run 1 qt higher in the stock pan.
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Old 07-11-2010, 05:50 AM   #330
masterx81
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Yes, there are some restrictions to balance the flow between the rod bearings 2 and 3 (that split flow from the main #3) and rod bearing 1 and 4 (that have both a dedicated supply from main #1 and #5). I've opened a thread recently speaking about this restrictions ( http://forums.nasioc.com/forums/show....php?t=1983477 ).
The only downside that i see using the external bypass is that MAYBE the stock oil pickup pipe can be too small (and cause cavitation at the pump due to lack of supply). While the engine is at maximum rpm the pump is recirculating most of the oil in the pump itself, actually not sucking it from the pickup. If you move the recirculating valve, at high rpm, the pickup pipe is flowing much more oil...
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Old 10-30-2010, 08:26 PM   #331
masterx81
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I see more ando more aftermarket cranks with 2 and 3 rod bearings feeded also by mains 2 and 4.... I'm quite interested to see the results of applying the same schema at an oem crank...
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