Filter Minders for Dummies

[davidbrady]

(03-26-2013 09:34)al perna Wrote:  Thanks David , sounds like a mod on the air intake makes good sense .

Hi Al,

Sure, I'd be glad to take some detailed photos of my intake system.

If the intake system's air flow restriction on our LXi's exceeds Detroit Diesels specs for clean and dirty air filters:

clean filter: 12 inches of H2O
dirty filter: 20 inches of H20,

then modifications make good sense. The point the others and I are trying to make in this thread is that we can't rely on the FM for that data - what the FM is telling us may be an anomaly. To determine if restrictions exceed spec we need to measure the pressure drop from the inlet of the intake system to 5 inches before the turbo. We need a differential pressure gauge.

If we're grossly out of spec, believe me, I'm going to be the first in line to make some mods, but for all the reasons listed above, I don't think we are. My hunch is that there's something else going on with the FM.

Before letting someone make changes I'd like to see proof of the actual pressure drop on our stock systems. Remember, there's always trade offs. BB and other manufacturers have a long history of positioning the air inlet up high, above the plume of road debris and moisture kicked up by our drive and tag axles. The stock air filter is well protected from excessive moisture, the air inlet is housed in a box of relatively still air protected by a louvered panel, plus the stock air intake system does a good job of keeping intake noise at bay.

Over the years I've grown to respect the choices made by Blue Bird. Often what seems odd at first glance is actually the correct thing to do once the science is understood.