Inliners International Forums General Discussion Engines 230 full flow or not

Still looking for the filter.

The only one I have found so far, is Fram HP8... high performance, very high flow numbers, and constructed to withstand high pressures.. has both anti drain-back and bypass valve. Bypass opens at 22psi though.... is that bad? I have a high volume pump.

Two bad things can happen.. bypass doesn't open when it should, starving the bearings of oil. Or it is open too much, sending unfiltered oil through most of the time.


I should add.... the way the bypass works: at cold start, there is zero pressure ins the main oil galley, and heaps of pressure coming from the pump to the filter. The bypass should be wide open to protect the filter and allow adequate, fast flow to the bearings and such. Once oil fills the oil passages, it starts building pressure AFTER the filter. When the pressure after the filter has reached the trigger limit of the bypass valve, the valve closes and all oil flows through the filter. The valve opening pressure does not refer to the absolute oil pressure in the system, but rather, the pressure DIFFERENCE between different sides of the filter. If there is 30PSI on both sised of the oil filter, the relief valve sees ZERO pressure differential and will not be open. When the filter gets dirty, the pressure builds higher inside the filter as the oil cannot flow through as easily, and the pressure in the main oil galley drops. The difference in pressure then eventually reaches the opening treshold pressure of the built-in filter and it starts passing unfiltered oil through.

So... the only filter I have so far found that has the features I need, has a 22psi pressure differential opening point. Just wondering if that's good or bad. I have seen lower numbers on other filters (Just for reference, they don't fit this engine).