Air filter interval

Changed the air filter recently, at 14k. It was horrible, far worse than I have ever seen.
This is my first turbo…it seems reasonable that a turbo would be harder on the air filter,
now that I think about it. Does anyone know about this?

Not clear to me why a turbo would be worse, need a given amount of air to burn a given amount of gas, so it should be a combination of miles and gas use that drive dirt accumulation.

More to the point is how much time was the filter in use . Those are mostly time change rather than miles . Plus where you are located has a bearing on the filter also .

A Google search shows that the engine air filter should be changed every 12 months or 15000 miles . One site said if not in a dusty area than 2 years might be fine .

I worked for a major filtration company for over 30 years.

And the dirtier a filter becomes, the more efficient it becomes.

But there comes a point when a dirty filter effects performance.

That’s why some filtering systems have a delta P indicator.



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I have owned 3 turbo cars over the years. One for 83K miles, another for 108K and now 44K. None of the 3 dirtied up their filters any faster than non-turbo cars.

The only reason I can come up with has nothing to do with it being a turbo - are any crankcase fumes routed to the upstream side of the filter? This used to be common with carbs in the '70s, one side of the air filter would end up filthy.

2019 Honda CRV. I doubt it.

Cleanliness of the environment, dust, pollen etc., is a big factor.
Using a restriction gauge my last air filter went 43K miles to reach 11", which is conservative.
Manual calls for 30K changes.
Boats often don’t use an air filter at all, the air over water is so free of particulates.

We can’t fob it off on the environment.
We have another car driven in the same places,
about the same miles, without this mess.

Any chance of a photo?

A turbo engine takes in more air than a normally aspirated engine over the RPM range.

That’s how a turbo engine produces more power.

More air + more fuel = more power.



and that would explain more dirt on the filter.

It the turbo engine uses the same fuel over the same distance, it takes in the same amount of air. Unless @melott is racing around, he’s using about the same amount of air and gas as he would have with the larger non-turbo engine they used to have.

The only source of an increase in filter throughput would be air vented by a blow-off valve. I have no idea how much that happens.

My Corolla’s HC emissions measure around 125. I have always replaced the engine air filter just before the test. One time I forgot, left the old air filter in, and that time it tested at 80. I wonder if that’s why?

You don’t need to be racing around for the turbo in your car to operate.

In the old days of turbos, the geometry of the turbo was fixed.

That meant the turbo didn’t kick in unless you got on the gas to get the turbo to spin fast enough so the compressor built enough boost pressure to create power.

But the turbo in your car is a variable-geometry turbo charger that’s computer controlled.

These types of turbos operate throughout the engine RPM range.

Even taking off moderately from a stop, the turbo is operating to produce more power.

And operating at high speeds, the turbo is operating to produce more power.

That’s the major benefit of a variable-geometry turbocharger.

So, you will see the air filter in your turbo car get dirty faster than the air filter in your normally aspirated car.


Sorry, I don’t get it. I understand all about how turbos work, how they can deliver more power, etc. But if he’s getting 30 mpg, he’s using the same amount of air, whether he has a 1.5 L turbo or a 2.4 L NA car.
What am I missing?

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There is adifference between “fob it off” and " a big factor."

The difference could be due to where each vehicle draws in air (front, side, wheel well, etc.) and the path the air takes leading to the filter.
If the air goes uphill to the filter a lot of the larger material won’t defy gravity and make it up to the filter unless the flow is strong.
Some intakes travel mostly sideways, so more stuff rolls along, like tumbleweed.

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I’d guess you aren’t missing anything. You seem totally correct on this point. The amount of air that passes through the engine air filter is very close to directly proportional to the amount of gasoline used, turbo or non-turbo. It has to be that way b/c a single gasoline molecule requires a fixed (& known) number of oxygen molecules to burn correctly. Same total gasoline use, same amount of air.

If there actually is an engine air filter life difference, turbo vs non turbo, a couple of ideas

  • a turbo engine requires a higher air flow rate at peak boost times. The brief but higher air flow periods may eventually damage the filter enough that an earlier than normal filter replacement is required. Sort of like how the roof on your house isn’t affected much by the normal daily winds, but it might get severely damaged in even a short-lived hurricane.

  • gunk from the turbo could conceivably get blown back onto the engine-side of the filter, so with turbo filter is damaged in both directions, causing it to fail sooner.


I agree with @circuitsmith. Intake location may have a lot to do with dust levels in the air scooped up for the engine. Also, if the air quality has changed this year and there is more dust aloft, that would be part of the reason for early air filter clogging. An especially dry winter could account for it.

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