Racor 690 pre OEM comments & questions

[TDIwyse]

Installed Greg’s Racor 690S fuel filter system pre-OEM last Friday. So far so good (no loss of prime issues). Installation took me about an hour. Got a nice diesel bath from cutting the fuel lines (thought I was all the way through the line and removed the cutting tool only to find out a small section wasn’t cut through yet. Had to re-mount the tool and finish cutting before I could get the rubber hoses over the metal fuel lines to stop the flow).

The bracket that comes with the system allows the plastic water drain part of the filter to hang slightly below the side frame rail (but above the lateral rail that goes under the transmission). There is about an inch of room between the top of the filter and the bottom of the bed, so I’m going to re-drill the mounting holes and slide the filter up to get the water drain part above the frame rail. Greg said the bracket was originally designed for the 660 series, which is shorter than the 690 series filters.

A few questions regarding pre-OEM filtering:

I’m trying to decide if I will continue with the 2um pre-filter or move to a 10um pre-filter. With the 10um element, what is the efficiency at 5um? I thought there was a chart of particle efficiency versus particle size for the Racor 10um element somewhere, but I can’t locate it through the search function. IIRC it was about 85% or better for 5um and above.

For 5um particles and above, a 10um pre OEM combined with the OEM filter (let’s say it’s about 65% at 5um) would still give effectively (85% in series with 65%) 95% reduction in particles 5um and above. This would also increase substantially the filter change interval (a 2um pre OEM would have to be changed roughly 5 times as often as a 10um, wouldn’t it?) and reduce the pressure drop across the filters (10um has less pressure drop than the 2um).

Also, who has wired the heating element for the Racor filter assembly? Where did you connect the relay?

Thanks

[OC_DMAX]

If you just add the numbers up on efficiencies, it should work as you stated. However, in practice, it does not appear to work that way.

For example, take a look at the "Mega" filter (the one most talked about here). I have seen it stated that the filter has an efficiency of 98% at 2um. So when you use it in a Post-OEM position, you would expect the combination OEM+MEGA to result in something approaching 99% efficiency at 5 um. Now take a look at the data on Kennedy's website and you will notice that is not happenning (Not even close). Other factors are involved, even with the static measurements that people have been making on this website. Don't even think about starting the engine and driving the truck (vibrations, injector pulsing and whatever else).

I remember Hoot posting that the 2um Racors are really 98% efficient at 4um particle size (per his conversations with the Racor Corp). I would think you really need to stick with your current 690S filter. Going to anything else would put you in jeopardy of meeting the 15/13/10 ISO cleanliness level prescribed by George Morrison (and which is support by various papers I have reviewed on the topic). I think you need to be way overkill in this situation. Don't let the math numbers fool you.

I have a copy of that Racor performance graph you mention. Email me at "abetker(at)yahoo(dot)com and I will send you a copy. By the way, you do recall correctly, it shows an efficiency of 85% at 5um for the 10um filter.