Air filter upgrades?

K&N air intake doesn't necessarily work well for all cars. 4Runner is one of them. This 4Runner guru (www.GadgetOnline.com) dynotests & proves that K&N drops the HP on his 4R. Toyota Racing Development (TRD) concludes the same thing as well.

My personal favorite is the TrueFlow (www.TrueFlow.com). It's a "full volume foam filter". After installing their air filter + air intake, my 4R is as quiet & stable as a Jaguar at idling. With better acceleration & fuel consumption too. Unfortunately, they currently have nothing for the Prius.

 

K&N makes very good filters. Their air filters are washable and reusable. A light oil coating permeates that filter material and thus helps trap impurities in the incoming air. The idea is that a very light filter media that is coated in oil will do a better job of trapping dirt while at the same time allowing a greater air passage rate even as the filter becomes dirtier, as compared to a regular paper filter. But K&N filters require maintenance that regular paper filters do not. Washing and reoiling, etc. However you are not going to dispose of a K&N at nearly the rate you would with a regular filter.

When they actually offer a filter for the Prius, I would be interested. However, the last time I checked they did not offer a Prius filter.

 

K&N, AMSoil, TrueFlow are all reusable air filters.

Read about how does the K&N compare to AMSoil here:

GadgetOnline.com Air Induction: K&N & AMSOil comparison

 

I checked with K&N within the last week or so and they do not have a Prius filter yet.

As an aside, I think the factory recommendation of 30,000 miles for an air filter change is waaay too long. I looked at the filter in our Highlander at 20,000 miles and it was loaded. I judge a filter's life by holding it up to light and being able to see light come through the pleats. The 20k filter allowed no light to pass through, indicating it was pretty well saturated with dust and dirt.

From now on, I plan to replace my air filters at 15k mile intervals.

 

Areometer,

Your test information is very conclusive. I find it intriguing. But I wonder, if your 4Runner were not supercharged what the results would be.

 

Wish that I had the answer for you. But I don't, sorry. My 4R is also supercharged. I am sure that K&N works well on 'certain' models. But if it lets more dirt through than foamy types like TrueFlow & AMSOil, then I prefer the foamy ones.

 

YES there is a K&N filter for the PRIUS 2004 model(I dont have the model # with me). I have had it for the last 20k miles, 8 months-bought through Kragen. No change in mpg at all. No driveability changes.
K&N install instructions were wrong. You need to cut the existing gasket in ~half so the new air filter is flush with the other half of the gasket.
WARNING WITH OILED AIR FILTERS !!!!!
There is a charcoal filter in the top of the air filter housing. Oil may clog or reduce the effectiveness of the charcoal. My understanding is the charcoal is there to reduce fuel emissions when the engine is not running. p.s.-I have heard you can pry this out of the top of the air cleaner.

 

By universal, do you mean those mushroom or cone shaped air intake? Actually, Blitz installed something just like that for their turbocharged Prius (FYI: they will NOT release this turbo upgrade):



I don't have a clear or professional answer for you. I wish that others would chime in. But before I take that route, I would upgrade the air filter with foamy type filters (whenever that is available) first. This is a lower risk upgrade for me.

200Volts, can you take pics of the K&N please?! Thanks for the tips regarding the charcoal filter.

 

OK here's my K& N model #33-2186 that I bought Kragen installed. It is the same thickness as the OEM gasket so you need to cut the gasket almost in half.

 

It also depends on what type of mass air meter you have. All oiled air cleaners have a certain amount of oil carryover downstream, that is to be expected.

If you have a hot-wire or hot-mesh mass air sensor, that oil carryover could really bugger up the mass air meter.

For the most part, I stay away from the oiled air cleaners. Most of the time, their claims of HP or MPG improvement are wishful thinking. And most of the cone-style oiled air filters violate EPA or CARB requirements so are for off-road only.

However, in very dusty conditions, an oil bath precleaner works wonders. That's why you find oil bath precleaners on most medium and large tractors and Cat's.

 

I have a 2002 Prius with 40,000 mile on it.

I replaced the paper filter with a K & N at 10,000 miles.

The first thing I noticed was when excelerating the displayed MPG would not
go lower that 10 where as before I could bottom it out. It's hard to judge
the amount of improvement in pickup and MPG improvement. I believe
the car has a little better pickup and the mpg has improved a little ie 1 or
more MPG.

I just picked up my second Prius a 2005 (am pkg), I just went out and checked out the air cleaner and it appears to be the same filter only now in a plastic holder. I tried the 2002 filter in this 2005 frame and it fit, I think
I will be ordering another K & n soon.


Tom
Minneapolis,Minnesota