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Old 08-05-2006, 08:41 PM   #1
Scooby Specialist
Member#: 64494
Join Date: Jun 2004
Location: Australia
2001 V7 sti

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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