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<x-charset iso-8859-1>Hello- > I was going to post this when things calmed a bit but Shad has probably > already delt with this so: > > With the new Notch engine the hot oil pressure is about 5lbs lower than it > should be... > well, when compared with a stock engine. Im running full flow on the Notch > and I was told by a mechanic locally here that there have been issues with > pressure drops over the Fram oil filters. The mechanic is correct, but that doesn't directly reflect the oil pressure problem. That's like me saying: "What's the temperature like outside today?" and you saying: "Well, there's a couple clouds in the sky." > Are fram too restrictive? is there a better brand to use that is less? > what should I expect in pressure reduction? The primary sucky point of Fram is the filtering itself. Get a K&N, Purolator, Mann, Wix, etc. filter - they are good quality. > Lastly... why is there an issue with oil filter pressure problems with full > flow? Again, it's the temp vs. clouds problem... First, let's look at your oil system after the cooler, pump, filter, etc. Pretend that you put a fitting into the galley and you pump whatever you feel like from somewhere else. For given rpm and given load and given oil temp, you can determine the flow rate needed to make a certain pressure. More flow = more pressure. If the bearing clearances are too big (or they're too old), the oil is too hot, the load is too high, or the rpm is too low, the galley pressure will be less. (Yes, it is LOW rpm that kills correct lubrication, not high rpm, so no hard lugging with hot oil :-). Now, put the filter and cooler back in. What you'll find is that the cooler and filter create a pressure drop. For the same galley pressure, you'll get the same flow, but the pressure BEFORE the cooler and filter is higher. This is normal. Now, put back in the oil pump. Idealized, it is a constant flow device - more rpm = more flow. But, in reality, it is not a constant flow device. If it has to pump to a higher pressure, it will leak back some oil. This is okay - they all do. While it is possible to make a nearly perfect gear pump (like in 5000psi hydraulic aviation systems), they aren't needed in our cars due to complexity. So, we have this problem. Now, with thin oil and a needed certain pressure, the oil pump can't keep up at the rpm you are at, so the flow and pressure drop. Swapping out the filter *might* help a *little* bit. However, unless the filter was totally clogged, it won't do *that* much. Get a new pump (perhaps a bigger one), blueprint it, and watch the pressure jump back up to the happy range. Next question: why do we need X oil pressure for Y rpm? Ah, complex answer... I have to leave soon, but if still interested, I'll respond in a week or two when I get back to IL. Remind me. Take care, Shad Laws LN Engineering http://www.LNengineering.com ------------------------------------------------ To unsubscribe, E-mail to: <type3-off@vwtype3.org> For more help, see http://vwtype3.org/list/ </x-charset>