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N54 rod bearing change

Engine Building Fundamentals

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Discussion and questions related to the course Engine Building Fundamentals

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My track car is a BMW 135i. Like others I have observed low oil pressure transients on track. Transients as low as 5 psi can be triggered by LH turns, particularly when there is a quick right - left transition with some unweighting. Oil levels below maximum definitely makes things worse. A bit of overfilling seems prudent, but overfilling by up to 1 liter doesn't fix the problem. One of my local tracks has a corner sequence that is a very reliable trigger, but luckily the lowest pressures occur at light throttle. A recent installation of dual (series) oil coolers in place of a single cooler has made the problem slightly worse, presumably because of the additional pressure drop across two coolers (the coolers being between the pressure pump and the engine). The N54 has a low oil pressure switch, not a transducer, and there must be some delay in the indication because the light doesn't appear on track (I think, I am kind of preoccupied with driving), but once I installed a transducer and started logging the data obliviousness was not an option. An accusump is an option I am considering, but addressing the problem at the source by adding a sump baffle seemed like a better first step so I am starting with that. I have changed all the rod bearings and would appreciate an opinion on the condition of the old bearings. There is a bit of wear and galling on the surface plating, and on a couple of the upper shells the copper substrate is just starting to appear. None show any sign of heat marks. How far from disaster was I with that level of bearing wear?

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