Going off on a tangent here...Anyway, yesterday I replaced my old air filters w/new OEM ones after recently hitting 30k miles (Man, were the old ones DIRTY!!). Going to work this morning I definitely got a small MPG bump (normal driving/freeway condition) according to the trip computer. It'd be safe to say that performance/responsiveness has been restored, too, but my butt dyno isn't as sensitive as some of yours. =)

 

Let's assume the K&N filters offer exactly the same performance as OEM filters.

A pair of OEM filters = ~$20. When it's time to replace, simply throw away the old ones and pop in the new ones.


A pair of K&N filters = ~$100. When it's time to recharge the filters you need to buy a K&N recharge kit (~$10; will last numerous recharges) and spend the time cleaning, re-oiling, and allowing the K&N's to dry.

According to the manual, you're supposed to change the filters every 30K miles. This means it'll take you AT LEAST 150K miles to justify a cost savings by purchasing K&N filters.

 

your gas mileage increase might be several factors, but i'm not convinced k&n will make much difference. when i ran dynos on the various filters/intakes, if what u said was true, then I would have seen more power sooner and everywhere. What I've seen where k&n did make power was 6k rpm and up... and that was on a turbo car, which makes sense because if u dont really stomp on the gas and run up the rpm, your car has plenty from air the stock filters.

In my experience, it was not worth my time cleaning the oily silcone residues, and trying hard to clean spots on the filter that can never get clean enough, not having a car while that thing dries, worrying about over oiling, etc. After about 3 cleanings, your filter wont be consistently clean everywhere which I a brand new stock filter will do its job better and flow air better at the spots where it counts most.

and yes, the k&n oil did mess up my MAF.

 

Just went for another test drive. Today I'm refreshed, was tired late last night after installing.

Man there is definatley difference. When I step on the gas the torque kicks in harder, the exhaust bit more deeper and humming. The air filters "unlock" G's power somewhat, maybe 5 to 8 hp gain in my opinion.

BTW i ordered my filters from autoanything.com, it was cool, i ordered them on monday and got em tuesday directly from K&N company in Riverside, CA, with K&N tape seal and all, I guess they route their to K&N directly.. Previously I went to Kragen, autozone, pepboys, they wanted $60 per filter which is rip and above retail price and they have to order it and you have to wait 3-5 days.
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2008 G35 journey5AT ivory/stone+prem&sportpkg.(k&n air filters)

 

It's worth it to me to have K&N's just so everytime I get an oil change they don't try to hit me up to replace my "dirty" air filters. That drives me crazy. I have 14,500 miles and they have told me twice I needed to replace them.

Oh, BTW I just dyno's. K&N's by themself took it from 270HP at rear wheels to 389HP, not bad for $100.00 I then pulled a 10.99 at the drag strip.

seriously though .7 to 1.2 MPG is a 5% increase which is pretty good. I have tried everything and never gotten better than 17.1 MPG around town ever. It has definitiely increased, but in the grand scheme of things it's pretty small.

 

isn't the air filter under warranty? because from what I remember....when I had my 2005 sedan....They change the air filter for me for free. Maybe its just in Canada.

 

no wear and tear items are under warranty.

 

No, not covered under warranty...maybe they just included it in the maintenance package?

 

I think it's the placebo effect. Nobody on earth can sense a 1-3hp/tq increase. There is no way in hell the drop in K&N's give 5-8hp. I can guarantee however that if you have your oil analyzed you'll see a significant jump in silicone. Most cars have one filter and silicone numbers jump up. I can't imagine what 2 will do. When this happens, it lowers the ability to go long oil change intervals. So the K&N filters actually cost you money instead of saving money.

 

I want to share my experience:

1. I installed the stillen intakes. Nice growl.
2. Installed the FI Exhaust, a lot of growl :-)).
3. Car start to have problems in idle.
4. Remove Stillen intakes and put stock boxes. I lose high end growl and a little power,really like low en torque now.
5. Planing on testing KN on stock boxes.

 

I'm very impressed with K&N filters. I was somewhat skeptical to begin with. From past experience with drop-ins for civics and tacomas, no difference... perhaps cuz they are low horsepower cars. But they have made a pretty damn good difference for the G35, overall the engine is more hyper and eager, the throttle hugs and responses noticeable better.

The engine and exhaust sounds better too. The psssst turbo air sounds between gears is becoming louder and starting to have a high pitch noise. No noticeable gas mileage difference yet...

I dont recommend wash and reoiling k&n filters cuz washing(the drying part) will screw up the cotton unless you dry the cotton in a dark vented room with a humidifier. I plan to do dust tapping every few thousand miles and buy another set of k&n at 50K miles.
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2008 G35 journey5at ivory/stone+prem&sportpkg(k&n airfilters)

 

Remove you're air filters completely. Dyno car. You'll likely gain 3hp tops.

So, do you really think swapping one air filter for another will make a difference in power or fuel economy?

It won't.

The only way your car will gain significant power or fuel economy is from a complete intake swap..... IF your stock intake is restrictive.

Ours isn't.

I purchased a reuseable filter for my last car, but that's only because due to the ram air system setup, the filter got dirty every few thousand miles.

 

I used K&N in my Supra for about 50,000 miles. The intake parts of the car (down the valves) got so dirty when I pull the engine apart. I'll will never use K&N again for that reason. I have never seen such a dirty engine before. I have worked many cars/engine.

Just think about it, more air means for dirt. Otherwise how does air get in? Stock filters are the best them all. I don't see an extra 1 to 5HP worths the trades.

 

You have a point wrxrocks.

K&N dont void warranty. So i guess its okay. I can just blow my engine up before the 6 year 70K miles warranty and get new engine. I know someone who did that but I dont think I will.
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2008 G35 journey5at ivory/stone+prem&sportpkg.(k&n airfilters)

 

It can certainly void your warranty if the oil contributes to the malfunction of your MAF sensors. This was common place on Both Maximas and Altimas. Many denied warranty claims.