K & N air filter

search Prius III forum this has been discussed many times.

there are 3 views:
1) it works;
2) it has placebo effect
3) it is bad for your engine

I have K&N replacement filter on Gen3 for ~95K, and IMHO it may have improved MPG under some conditions with following footnote:
- when compared to clogged OEM (15-20K) filter
- it seems to improve response on light throttle.
So if you are gentle on throttle, run ECO mode you may see some improvements.

One of the nice things about K&N is reduced maintenance. You supposed to clean it every 50K, but in my experience they've gone 150-200K w/o need on conventional compacts, and unless you live in dusty area, may never need to be serviced on Prius, YMMV

 

The EPA did a study on clogged vs clean air filters. A clean filter will provide more peak power, but not more MPGs. Unless your filter is absolutely disgusting, the throttle plate is going to be biggest restriction for 99.9% of most Prius' driving. So a K&N will most likely not improve mileage. However, you may save money from not replacing paper filters.

 

I purchased the K&N and returned it.

It needs special cleaning and special oil to "wet" the filter media.

I'm sticking with OEM filters. In the long run, they are just as cheap.

 

Take a clean rag.
Soak it in oil, and jam it into your intake.
Drive for 10K miles or until your MAFS gets dirty.
Then?
Take $50 and give it to a whino.
OK?
Now.....please tell me how this is going to suddenly manufacture horsepower or make your engine 5% more efficient.

I'm just a little bit of a hard sell on this...and I actually OWN a high performance filter......

....For my motorcycle!
No. It doesn't save me any fuel. As a matter of fact, my mileage went from 48 to the high thirties.....BUT I also radically changed my exhaust and remapped my ECU.
I would NEVER EVER soak my filter in oil, and I went with an AMSOIL Ea unit, which I just have to accept the cost of changing out every 10K. AMSOIL products are generally snake oil, but their AIR filters work well for my application.

That's just me.
The reason that this isn't going to do anything for your car (IMHO) besides maybe FOD out your intake system is that your engine is like an air pump. You might(!) be drawing more air in with the the oily gauze rag, but you still have to exhale through the same restrictive exhaust system.
That's why all of the wanna-be ricers have the fake coffee can exhaust tips on their cars.

Meanwhile......since you have a closed-loop FI system, your ECU is going to keep your air/fuel mix where it always does, so even if you do uncork your exhaust, you have to talk your computer into squirting less gas into the motor to lean out the mixture and somehow do this without evil things happening deep inside the crankcase.

For my setup (06 V-Rod) I wanted more BHP, and I paid for it (nothing is free!) with lower fuel efficiency and having to pay for a $40 airbox filter every 10,000 miles. I spent about $200 and gave up about 8 mpg for a 7-10 BHP gain at the rear tire, which isn't bad for a motorcycle.

Priuses are good at being Priuses.
If you want to blow money on some engine candy, then see if they make a dry filter (AMSOIL used to with the Ea line) and paint the induction pipe some neon color and have a blast with it!



......just don't try to sell me on the idea that you gained any fuel efficiency that way, or turned your Prius into a tire-smoking, fire breathing drag strip monster.


Good Luck!

 

im running a k&n drop in filter. it works great for me and isnt a problem. now that its winter here, i might switch back to stock so the engine can benefit from the warm air. on my last tank of gass, while running the k&n filter i averaged about 53 mpg. that was mostly short <10 trips and maybe 2 or 3 long (30 min) trips. but if you live in a dusty or dirty place then the k&n might not be for you, since if not properly oiled, it will allow more dust particles in the engine.

 

you need to clean it every 50,000mi, and unless you live in dusty conditions you will never have to clean it on Prius

 

There is ONE area where the K&N could theoretically be worth something.

If you presume a 300,000 mile life cycle for the car, you could theoretically save some land-fill a few dozen plastic and paper filters, plus whatever notional theoretical carbon throughput is involved in manufacturing about 15 of the filters.
Just be VERY careful about oiling it and become familiar with how to clean your MAFS and TB.

Priusers tend to be a "green" bunch, or at least they like people to think that they are.
Personally?
I still think that they're junk, but if you're REALLY into the bunny-hugging thing?
It is something to consider.

 

See this video, where they actually dyno test a K&N:

Performs no better than a paper filter.

 

It's been conjected that future civilizations will be "mining" land fills.


BMW is already using methane from garbage dumps, here, down the street from me.

 

Yeah, well that's not my patch.
Environmental geeks can argue better than social workers about the stupidest things, and in the end I don't think that paper wrapped in a little plastic is the stupidest thing that you can put into a land-fill.

I was just suggesting that there is a possibility that the K&N filter might be theoretically good for something.

 

The OEM filter is specifically calibrated to trap particles of a particular size.

I can't see how cotton fiber impregnated with a oil can be calibrated to do the same thing.

The ability of the oil to capture particles will depend on the "stickiness" of the oil, the speed of the airflow and how much the particles have already loaded the oil wetted surface.

That would mean that there is a possibility that some larger particles will get into the engine, as larger and more massive ones would be less likely to be captured by would break free of the oil wetted cotton as time goes by.

I'll stay with the OEM filter.

 

as it was said, there are 3 views:

1) it works;
2) it has placebo effect
3) it is bad for your engine

 

Smart move!

 

I have gone 100+k with K&N with no issues on my other cars.

Here is some info if it helps from K&N


K&amp;N Response to Mass Air Flow Sensor Concerns

 

I just install a K&N with 29500 miles on my original filter.

Here is my impression.

Noticeably more throttle response on the low mid range.

ICE on transition is slightly smoother.

Not sure if any top end power was gained?

0-60mph was 10.6s on the Scangauge 2

0-55mph was 9.4s going the other way. Didn't hit 60mph even though the stock gauge showed.

 

please note OEM filters are water proof, so therefore can be cleaned, ok it will not come up as good as new, but will enable it to be reused at least once