Originally Posted By: tommygunn
I'm not convinced purely looking at beta ratios indicates a smaller filter is better personally...
Perhaps not, but data is data. If it cannot be used to prove a smaller filter is better, then it cannot be used to prove a larger filter is better, can it? Beta data is certainly more informative than nominal ratings, which are nearly worthless.
Full ISO testing data would be even more revealing, but good luck trying to get filter makers to releaes that info. Wix was (as in past tense) one of the only major makers to post their full beta data, but that is gone now.
The beta data is reasonable and shows relative performance. The 51307 is indeed "better" than the larger 51515 that essentially has all other characteristics being the same when it comes to efficiency. Gary Allan and I theorized that it has to do with media density, etc. Part of Gary's "filtration triangle".
Regardless, the data speaks for itself. Larger is not always better when it comes to efficiency. One cannot look at the physical can and declare with impunity that any filter is "better" than another for efficiency.
About the only thing one could spend time debating is what "better" really refers to. For most people, they're are in a quest for contaminant reduction; better efficiency. But what most people don't stop to consider is that most all filters are already "good enough" to provide a level of cleanliness satisfactory to ensure a LONG equipment service life.
The typical benefits that can be realized are commonizing filters across many pieces of equipment, where the balance of the filtration triangle (size, lifecycle, efficiency) is suitable for a large range of the fleet equipment. And convenience plays into this as well; one member mentioned that he uses a larger filter so that he has no leftover oil from the 5 qrt jug. Fine - nothing wrong with that. For him, that is how he defines "better".
The OP was simply asking why not use a larger fitler if he was already going to pay $10 for a premium filter. He asked about flow, in particular. OK - yet another topic. A larger filter will not necessarily flow more, at least until the media would be closing down with particulate load, relative to another smaller filter that would go into bypass (full flow but with no filtration). Fact is this though; most common filters flow WELL more than the engine requires. Many filters are rated at 7-10 gpm flow rate. That is way more than the the engine will need, and much more than the real flow through the typical engine, probably on a factor of 2x. So, perhaps a larger fitler will flow a tiny bit more (although that's not typically borne by the filter data). But who cares? If you accept and understand that ANY filter is WAY MORE capable than needed to support good flow, the small minute differences between filters are meaningless when it comes to equipment protection. Flow through the filter is predicated on two concepts, and they are counter indicative. Which would you believe?
1) your filter application is engineered with a large safety margin, and no amount of swapping from brand to brand or size to size is going to effect the result because the filter is NOT the point of restriction; it represents a minimal pressure drop and flows far more than the engine needs.
2) your filter application is poorly designed and executed, and the max filter flow is so close to the critical minimum engine requirement that changing a filter will make a huge pressure and flow difference.
Which seems more plausible to you?
When UOA data shows that any properly spec'd filter is utilized, wear is not generally effected in the real world. Nor will flow be effected to a point that it makes any difference. Nor will small changes in delta P across the media. Size, efficiency and lifecycle are inter-related. If you hold one constant, the other two will become inversely reactive. But those changes in altering the characteristics do not usually manifest into perceptible effects in wear reduction, which is the real goal of any filter.
This thread (and the multitudes of so many like it that get asked over and over again) is about "is larger better?". In a real world pratical sense, when it comes to actual measurable performance that would lead to altered equipment life in the user's possession, the answer is "typically not".
