Discussion and questions related to the course Practical Engine Building
I am rebuilding my FA20 engine (BRZ) for forced induction and am concerned with the oiling system not directly feeding the mains. I have heard of track guys with oil pressure drop at high rpms and spun bearings. Do you have any specific advice on further modding the FA20 oiling system?
It's actually something I'm going through at the moment and unfortunately I don't have anything solid to share. I'll assume you're referring to the very long thread that covers Element Tuning's car in the US. So far I've found no conclusive modifications to fix the problem. The FA20DIT oil pump isn't a direct fit and also appears to not be a viable solution anyway. Personally I've used a heavier oil and found this to give me acceptable oil pressure. We run a 10W40 at the moment. What I don't like in the FA20 is the dramatic swing from cold to hot oil pressures. It's more excessive in this engine than any others I've built.
Hey Andre, I greatly appreciate your reply. Ya I read that thread as well as other info from online research and talked to some racers+workshops, which made me concerned and wanting to address this issue when building my engine. Would you recommend shimming the oil pump by adding a washer to the oil pressure relief valve?
It's a tough one to recommend. In some instances it can help but the part I worry about with the FA20 is the massive variation from hot oil pressure to cold oil pressure. I regularly see in excess of 120-130 psi during a cold start even when being careful of the revs I use. Shimming the relief valve may help hot oil pressure but is likely to make cold oil pressure even worse.
From those symptoms, I would suspect the oil pump is marginal for keeping up with the internal leakage (ie, through the bearings, valve train oil supply, etc) and a quick look suggests the REIMAX* pump may be a viable, though fairly expensive, upgrade - especially as there seems to be problems with the OEM gears breaking up?
Of course, if you have the budget, a dry sump setup might be the best cure.