Filter Minders for Dummies

[davidbrady]

Hi Al,

Thanks for asking. Yes, with a reduction in intake restriction, fuel economy and throttle response should improve do to a lessening of pumping losses. I don't think power will improve unless the fuel map is changed, turned up.

My intuition is that we haven't identified the root cause of our yellow and red zoning Filter Minders, and blindly throwing air flow improvements at it may mask the root cause and result in unnecessary intake modifications.

I believe this for a number of circumstantial reasons:

A) my bus runs too good for there to be an out of spec induction system, I have low turbo lag, power and fuel economy are exceptional, and it never smokes. It just doesn't behave like a bus that's choked,

B) a visual inspection reveals an intake system that should conform to spec: starting at the turbo, there's a 6" ID 90* elbow, into a 6" ID x 48" tube with one 90* elbow, into a 7" ID 18" air filter, then out the top of the air filter into a bell topped 7" ID x 18" tube which pulls air out of a large still box. I count three 90 deg bends. The restriction imposed by the paper air filter should be negligible compared to the restriction of the system overall.

C) What we have in our LXi's is almost identical to what Prevost uses except they have an additional 90* elbow and their 6" tube is 5.5" ID. They also have a 20" of H20 Filter Minder installed.

D) The zoned-out FMs occur on WB's (8V and S60) and LXi's (S60), and maybe other wanderlodges that we haven't identified yet. The fact that it seems to hit all the 500hp buses leads me to think that there's something else going on, and that could be where the FM is mounted, conditions within the engine compartment, tolerances, resolution, and calibration of the FM's themselves. I'd be surprised if BB undersized the induction systems on all these buses for almost a 15 year period.

E) I spoke with the folks at Filter Minder and they confirm that they've seen problems with zoned-out FM's in bus applications. Could be the vast intake plumbing to and from the Charge Air Cooler, could be the size of the Charge Air Cooler, could be the high power cooling fan blowing air into the engine compartment and over the FM, could be the nature of a high power diesel pusher.

This topic has captured my interest so I will eventually instrument my intake to get some hard data. We need a differential pressure gauge set up to measure the vacuum drop properly to see if the intake is out of spec. I think it merits more investigation.