So I've searched thoroughout this forum for an answer to whether a drop in air filter replacement will actually give any performance improvements. The three that I've seen mentioned are:

K&N: Oil with cotton
Green: Oil with cotton
Blitz: cotton/poly no oil

I've also read that there may be potential issues with the Mass Air Flow Sensor (MAS) with some of the oiled filters. I wasn't able to find any before/after dyno numbers other than a K&N one in a G35c, however the dyno was from K&N so I'm immediately suspicious. It showed a 5-8hp gain.

I am especially looking for any feedback on the Blitz drop in filter since it is not oiled and seems to therefore be the less risky of the three to use.

 

The Nismo S-tuned Air Element is a dry type and will give you around 3 horses.

 

Blitz, from what Ive heard, doesnt filter out harmful particles very well.

Check out the threads about the ECU negating gains on bolt ons too.

 

This is JUST my opinion, but since you asked.

The gains from an aftermarket filter are small. Nobody has seen large gains, and some people have seen the ECU negate the gains later.

It is also true that the oiled filters can cause oil to get on the MAF wire and ruin it. Some people say that is from an over oiled filter. I am not sure how precisely you can oil a filter since you do it with a spray can by eyeball.

One concern I have is that the MAF can be degraded, but not so bad that the computer spits out a code. In that case you would slowly lose power due to a degraded MAF sensor and possibly not know it.

Some of the non-oiled filters remove the oil problem, but there is some question as to how well they filter. I don't have much data in this area, but it sort of makes sense. A less dense filter can flow more, but it seems likely that it filters less to.

So, to me, (just me) the relatively small (or zero) potential power gain combined with the potential of a MAF problem make the oiled filters "not worth it" in my book. Others disagree.

To each his own I guess. My advice is don't bother.

 

how bout a high end intake like GruppeMs and K&Ns Ram air intake?

 

Well I would be willing to invest in a high end intake if the performance improvement from it was significant enough to justify the cost.

 

I had the K&N "Drop in filter" and did not notice any improvement in power.

I now have the JWT Pop Charger with heat shield. I feel that there is a gain in power from it. I do not notice any difference in the lower RPM range (below 4500). However, above 4500 RPM's to redline (WOT), I believe that there is an improvement in power. When I make the transition from 1st gear to 2nd gear my rear tires are "chirping & spinning" more as the rear wheels are trying to gain traction (my tires did do this before, but not to the extent that they do now). I am very happy with the JWT.

I am not endorsing this product. I am just sharing my experience & opinion of this intake. Thanks to the other posts, I made sure that there was not exsesive oil on my filter before install.

With the recent release of the K&N Typhoon, you may want to wait and see how it performs (member's dynos, testimonys).

 

Not for HP gain, but I like the sound of CAI's.......

 

The biggest performance gain is in decreased pressure drop in the airbox due to lower resistance through the filter. It may not flow a more significant cfm air load, but throttle response may increase secondary to less pressure drop. MAFs can be susceptible to oil debris. If it is a shielded heated wire type, it will far much better than the screen based MAFs.

 

I have a dyno sheet from a stock 6-speed G35 Coupe. K&N tested their drop-in filter and got the following results:

Baseline HP = 233.0
Basline Torque = 232.2

K&N Filter HP = 238.3
K&N Filter Torque = 237.5

Didn't post the chart cause it's real hard to read in the reduced size.

Will e-mail the full size chart if someone wants to see it.

 

I just did the K&N drop in, and I noticed a small difference.

 

You will not notice a huge difference but it will give you a slight bit more pull in the upper RPM's.

K&N Drop In Filter $39.95

 

I am suspicious of any numbers posted by the manufacturer of the product in question. They always seem to get better results than the rest of us.

Some people here have done whole CAI tests and only seen a few HP. That makes me wonder more about the K&N number.

Maybe this was for an intake kit, not just a drop in? I know the G35 will benefit from an intake kit more than the Z. Even putting a Z stock intake tube on a G35 will net you 4-5 HP.

 

Manufacturer's get their Peak HP / TQ numbers from the LOWEST pull baseline to the HIGHTEST post modified pull.

 

Do the math.
Stock filter w/ 12K miles = 3 in H2O drop (I measured)
No filter = 1 in H20 drop (I measured)
Assume 20% frictional HP (e.g. 287 *1.2 indicated = 344 brake)
2 in H20 / 407 in H20 atmospheric = 0.5%
344 * 0.5% = 1.7HP MAX gain
Assume 50% improvement w/ perf filter = less than 1 HP likely gain.
Gains may be even less if comparing against a new stock filter.
Make your own judgement.

 

The biggest gain in K&N drop in filters is what you gain saving in your wallet. Being able to clean them and reuse them up to 1,000,000 miles.