Originally Posted By: ZeeOSix
Fram's quoted efficiency is based on the
average of those 3 filters listed. They do seem to cover a pretty decent range of size which is better than doing it for one filter. This gives the reader some assurance that the efficiency of the Frams are pretty consistent regardless of the size of the filter.
Purolator uses only their largest filter (30001) to quote their efficiency spec. Plus, there are some Purolator filters that they rate at 40 microns instead of 20 microns, and you'd never know that unless you looked at the box those specific filters come in.
Right, it is the average efficiency of those three filters, which may mean the PH8A is better than the average and the smallest of the bunch is not as efficient (which, if we look at the Purolator numbers, makes sense FWIW).
The cited number, the percentage, is based on (the average filtering efficiency) those three filters. So that doesn't mean the FL-820S is exactly that efficient, which is what the comments in this thread, and FRAM's numbers, construed in the light in which they've been taken, would lead us to believe. That's why I've singled out that comment on their page because while I understand the quoted figure in reference to these "reference filters", that isn't to be taken as all of their filters are that efficient, if they were, they wouldn't need that statement to qualify the figure.
And yes, that brings us to Purolator's quoted efficiency too, which is, as you've noted, based on the freakin' huge FL-1A, which yields the "best" (best to advertise) efficiency ratings. It isn't until you look at the specs for a specific can (as you've noted) that many realize this.
Which takes me back to where I was going with my comments: We don't know what the
exact efficiency is for the PH2 here, we just know that the series in which it is a part of is noted as carrying a stated efficiency rating, but it is an average of the three filters already mentioned, not an exact rating that goes with every part #. FRAM's data on the PH2 doesn't give a specific efficiency rating, which I was hoping it would.
So, as I said, I'd like to hear from Motorking on this. It would be nice to know what the specific ratings are for the three filters averaged as well as, if possible, the actual efficiency of the PH2. Maybe it is really quite close to the average figure, which would be great, but if that's the case, I'd still like to hear it from him.
Like you've touched-on, some of the really small Purolator cans aren't anywhere NEAR as efficient as the FL-1A sized filter, and while the FL-820S/PH2 is a reasonably big filter, so it may not be effected by this like they are, it still has me asking the question