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Old 08-06-2006, 07:28 PM   #9
bugeyes
Scooby Specialist
 
Member#: 64494
Join Date: Jun 2004
Location: Australia
Vehicle:
2001 V7 sti

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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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