Originally Posted By: 1JZ_E46
Originally Posted By: Garak
I don't think there are any flow concerns on any of the synthetic filters, be they ultra high efficiency or not. For that matter, I don't think we have a lot of problems with restrictive oil filters of any sort on the market. There certainly are racing filters available out there, but I'd worry more about that if the performance engine had more flow than was the OEM norm for that engine.
Same flow as in stock form, except for an extra 1000 rpms until redline (8000). I think high-flow filters are used in racing, though, because they don't want any bypassing (I think a lot of race filters have no bypass valve). Most filters are bypassing during normal use, which is fine for street engines, but race/high RPM engines run the risk bypassing a large containment under load, taking out a bearing.
"Racing oil filters" usually have a higher bypass valve setting and are designed to take more delta-p across the media without failure. Racing filters still have a bypass valve ... it would be dangerous not to have one. It's the only thing that protects the filter from getting destroyed if the delta-p across the filter becomes too high.
The real "downfall" of a more restrictive filter is that it could make the oil pump hit pressure relief sooner, thereby cutting down the flow to the engine at very high RPM.
Most filters are not bypassing during "normal use". They will however bypass if you are running heavy oil and rev the [censored] out of the engine before the oil warms up and thins down some.