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Originally Posted by Tokay444
How do you fix the oiling issues?
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For the FA20 you have to add in an oil passage and restrict the flow on another to allow the journal bearings to be fed equally. A description of that issue is found on this very forum:
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Look at the FA20 crank mains and the rod journals and you should spot something unique where I oil starved the rod bearing. The third main from right to left has a larger oil port. Why? Because it has to feed two rod journals where all others only feed one rod journal. What happens to oil pressure when you increase the oil port size? What happens to your oil volume requirements when you need to feed two journals with one main? Guess which one failed?
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Additionally, there is problems with the design and manufacturing of the oil pickup tube which can be solved by swapping to the KillerB unit.
Finally, the oil pan capacity isn't really sufficient when pulling sustained lateral G. It's just a physical limitation of the horizontally-opposed design and gravity. A baffled oil pan can help some but you're safer with a higher-capacity baffled pan and/or an Accusump accumulator.
When someone mentions the "inherent issues with a boxer engine design" the obvious comparison - Porsche - comes to mind. Well, for their high-performance engines (most 911 models) they use a dry sump system from the factory. For the "lower-performance" early-gen watercooled engines in the Cayman and Boxter, their oil capacities were gigantic compared to the FA20 - almost 8 quarts of oil in the Cayman vs. 5.8(ish) for the Twins. And that's leaving aside design differences in oil supply and routing.
As far as I know - I haven't researched it as much as I wasn't even planning on build an FA24 - Subaru/Toyota didn't do anything to address the preexisting issues with the FA20's oiling, and in fact made it worse with the change to a multi-screen plastic oil pickup design. The addition of the now well-known issue of too much RTV being applied from the factory causing the oil pickup tube to become partially or completely clogged muddied the waters a bit, but overall it seems these issues will persist on stock engines.