Learned a $60 dollar lesson yesterday. I should have spent some time on the forums first, and would have saved myself some hard earned cash. Not trying to blast K&N here by any means, no doubt their drop-in filters serve a purpose. However, if you're looking for treating your Mustang to better airflow, and HP/MPG gains, than your stock filter, good luck finding it. A reasonably scientific test, conducted twice, both showing actual LOSS of power with a K&N filter. Guess the factory got this one right...


http://www.svtperformance.com/forums...lter-test.html

http://www.svtperformance.com/forums...ercharged.html

 

Yea, this is too bad for K&N and our Mustangs stock air box. I have a K&N "semi" CAI on my 2005 F150 (4.2 V6), as well as my 2000 Harley-Davidson dresser. In both of these, they have performed good, although I cannot testify with any dyno runs that they boosted any "seat of the pants" or other gains. The Harley is on it's second engine (first engine gave me 94K miles) and the second engine has 34K on it; both used the same K&N setup. The truck has about 57K on it's K&N CAI, and so far, so good as to filtration.

I had read on one of the various Mustang forums that the stock air boxes on these new Mustangs flow very well, and unless you go with a setup of a "true" CAI (sealed box type drawing in cold air; not the ones that are open at the top and seal around the hood (which does not work)), plus a tune, then the money spent is not worth any serious gains. The drop in filter was also not worth it in this case. Doesn't even pay off as a lifetime filter if it drops performance!

Thanks for the update and links; should we steer clear of a future classifieds ad of you selling it?

 

I agree 100%. the reason for the performance loss is that it flows much more air than the air meter needs, therefore causing a overly rich condition and th only cure is to run it wide open, maximum rpms.

you have to have a change in the ECU to take advantage of the extra air.

 

Really? **** guess I'll go with a CAI after all.

 

So, the K&N filter flows more air, but the ECU/PCM cannot "map" it with its stock tune?

If someone goes out and buys a CAI that does not require a tune, how do they (manufacturer) get away with stating that they still provide a 10 to 12 HP gain without a tune?

 

A buddy of mine is a semi pro race car driver, he told me flat out not to worry about a CAI or a filter if I'm not going to get a tune to go along with it, the results are minimal without a tune.

 

Interesting. I have a K&N panel filter. Only other power mods are FRPP GT500 mufflers (not really any power gain, just beautiful sound) and an SCT tuner with their canned 91 octane strategy tune. 409 rwhp and 1/4 trap speeds in the 116-117 range. I'll have to put the stock air filter back in to compare dyno and track data, then decide for myself.

 

We have a CAI that will help take your car to the next level .

PM if you need some assistance.

Best Regards,

TJ

 

I disagree. Bullitt picked up 15hp over the GT from the factory with the FRPP CAI, sealed hood liner, and factory tune. Please adds to that sweet Bullitt tone!

 

Rare exception; I guess that's why it has the seal of Ford racing approval. Most of the "semi" CAI (open at the top) are very cheap being sold these days on Ebay. Some don't even have a rubber seal along their top edge. You get what you pay for. Plus, you added a tune. The OP mentions a drop in K&N filter only (no tune) shows you LOSE a few ponies....

 

You obviously don't know tuning -_-

 

Personally I'm a little skeptical about the CAI vendors claim of power increase & MPG. But bought one anyways because I like the look and the sound of it. Also planing to add a tune after warranty expires.

 

i think the stock air filter is slight better than the K&N drop-in, is mostly because the stock one is so much "thicker" in that one direction, which is more surface area for the air to pass through, thus let in more air.

the stock filter design is quite nice on this car.

 

As the article you linked said, it's not a performance purchase, but you'll save money in the long term since you don't have to keep buying new $15 filters over and over.

 

True, but not worth the worry of over oiling the filter and messing up the MAF sensor, just my thought

 

Good point. To add to it, those that cannot follow simple directions for cleaning and oiling a filter should not be buying them in the first place. That's why paper filters are made.

 

Too bad the K&N turned out to be a disappointment. I was thinking about trying one since I encounter quite a few dust devils traveling the Mojave desert. I would like to see K&N make a reusable cabin air filter for our Mustangs as mine gets dirty pretty quick. Stock Motorcraft air filters / cabin filters are cheap enough at Rock Auto: http://rockauto.com/ even with shipping.

 

I like mine, but I am also a previous Pruis and Wrangler owner. I found it usually makes for a slightly more throaty sound. It was best on the Jeeps, ok on the prius and just fun on my mustang.

 

I like that at the bottom of the page is a K&N ad.

 

I just pulled my K&N out and put the paper one in. I installed the K&N at 500 miles with my first oil change and used Mobil 1 5w30 EP. I noticed a ~1 mpg drop and thought it was the oil. I'm not so sure now. I'll fill up tomorrow and run a tank and see what happens (I calculate mine, not trusting the car computer). I did notice a significant loss of intake noise with the paper filter vs the K&N, now I just hear my exhaust system which is better for me. I'm now doubting my plan to put a CAI and a tune on and just may install a tune and see what happens on the dyno. Any thoughts?