Weird Findings.

[The Critic]

I decided to inspect/clean the filters on the Altima and Prius this weekend.

The Altima had 9900 miles on it and is 20 months old. It is used mostly for 1-3 mile trips in a suburban neighborhood. The A/C is used as-needed during the summer only. I found the engine air filter to be fairly dirty (and will be replaced with a new genuine filter at the next service) but the cabin filter looked unused.

The Prius had 9100 miles on it and is 3 months old. The Prius is used mostly for highway driving and the HVAC system is almost always set to Auto. The engine air filter looked unused while the cabin filter was moderately dirty. Most of my driving is between SF and Monterey, on Highways 1 and 101.

Any possible explanations as to why I found what I did?

 

[Quattro Pete]

Isn't there a lot more air being taken in by the larger Altima engine? The increased air flow is how I'd explain the more dirty Altima engine air filter.

Not sure about the cabin filters. Maybe it has something to do with the way the air intake is designed on the Altima that keeps more junk from reaching the filter in the first place?

 

[d00df00d]

Originally Posted By: Quattro Pete
Isn't there a lot more air being taken in by the larger Altima engine? The increased air flow is how I'd explain the more dirty Altima engine air filter.

Not sure about the cabin filters. Maybe it has something to do with the way the air intake is designed on the Altima that keeps more junk from reaching the filter in the first place?

These would be my guesses as well.

 

[ARCOgraphite]

Is altima HVAC set to recirc? Thats all I got re: this "mystery".

 

[Klutch9]

Originally Posted By: Quattro Pete
Isn't there a lot more air being taken in by the larger Altima engine? The increased air flow is how I'd explain the more dirty Altima engine air filter.


This, plus the fact that the Prius' engine is not always running during vehicle operation, being that it's a hybrid. The Altima's engine is always on during vehicle operation.

 

[mechtech2]

Location and routing come to mind.
Where the air is coming from may be an additional reason.
For instance, an ultimately low pick up would have more dirt than a higher air origin point.
Differences in engine compartments, etc..

 

[The Critic]

Originally Posted By: ARCOgraphite
Is altima HVAC set to recirc? Thats all I got re: this "mystery".

Altima is NEVER set to recirc. Fwiw the cabin filter filters recirculated air on some cars too.

Originally Posted By: Klutch9
Originally Posted By: Quattro Pete
Isn't there a lot more air being taken in by the larger Altima engine? The increased air flow is how I'd explain the more dirty Altima engine air filter.


This, plus the fact that the Prius' engine is not always running during vehicle operation, being that it's a hybrid. The Altima's engine is always on during vehicle operation.


My Prius's engine is always on, mainly because I drive in hilly terrain and because I am on the highway most of the time and the ICE is on at speeds over 42 mph.

 

[dwendt44]

Neighborhood driving exposes the engine and its filter to "dirtier" air than the open highway.
Also, where either filter (engine or cabin) draws air from can make a difference. I low mounted intake for the engine would suck more 'dirt' that a higher, more sheltered intake.

 

[CBR.worm]

My wifes old Audi's cabin air filter always got nastier than her engine airfilter over any number of miles.

My infiniti's cabin air filters are good for about 50-60K, the engine air filters are not good for 20K. I don't know about the Altima, but on my Infiniti's the air filter element is pretty much visible through the grill, all the road grime goes straight in.

My last toyota pulled fairly clean air from inside the passenger side fender.