K&N air filters

This has come up a lot over the years on several threads (search "K&N"). As you would expect, there are two well positioned opinion groups with very strong and well thought out opinions.

K&Ns have shown on Ferrari dyno tests to increase hp -- not a lot, but some.** It's also shown that the paper elements while more restrictive, clean the air more thoroughly better protecting engine internals.

So, the discussion always distills down to a judgement call on how much - how much hp is it worth and how much difference does slightly less filtered air affect engine longevity.

I usa a K&N.




**If it is a carb car, the some actual airboxes are more a problem (search "Airbox restriction") and require a small mod.

 

I guess if you leave in an area where the environment and air quality is clean then it's good to use K&N Filter. BUT if you leave in an area like where I am surrounded by farmland where sometimes dusty, then you should stick to the original or better element.

 

I used K&N for a few month and noticed a slight increase in power over stock. Last week though I decided to try an itg filter (http://www.itgairfilters.com/) from superformance and I felt a substantial increase in power over the K&N filter, particularly at lower rpms (better throttle response). In addition the aspiration sound improved to a deeper growl.
No more K&N filters for me!

 

I'll second what both Russ (snj5) and Mike already said - a clean, new paper filter will flow as well as a clean K&N. A dirty K&N will flow more air than a dirty paper filter. The downside is that more airflow = more airborne micro-particles entering the engine rather than being caught by the filter.

This isn't just my speculation - it was proven in a oft-referenced study (though I can't remember the name of it now to save my life!) by some engineers conducting research for the diesel truck community.

You have to decide what best suits your circumstances and take into consideration the air quality in your area (i.e., do you live in a dry, dusty climate or a place that has relatively good air quality, perhaps from frequent rains), how often you want to deal with your air filter (clean vs. replace), the current condition of your car and mileage, and your long term plans for ownership.

I have a '79 308GT4 with an engine that (I'm fairly sure) has never been cracked open. I have 81,000 miles, and I plan to hang on to the car for a while and possibly do a rebuild at some point. That said, I have no problems running a K&N in my car(s). However, if I were to win the lottery next week and pick up a brand-spanking-new _________ that I wanted to keep *perfect*, I'd likely stick with the (better filtering) paper filters and just pony up to replace them as needed.

As always, your mileage may vary.

 

My strategy is use stock paper for street and K&N for track. The street is dirty and no need for extra VERY few HP anyway. Use the K&N for track as the track is generally cleaner, the engine breathes a bit more AND MOST IMPORTANT is that the K&N has a wire mesh to stop larger debris (clag, etc.).

So street = stock, catches more dirt, works fine as street is slow speeds and average low(ish) rpm

Track = K&N due to less dust debris but big clag debris means desire for K&N's wire mesh. Due to higher average rpm the added air/breathing helps.

 

I picked K&N because it was all I could find easy.

I would rather have a fliter that filters more, in general. Where can I find one?

Seamus

 

If it is a carb 308 we are talking about, Baldwin makes an excellent air filter for nearly half the cost of the K&N - P/N: PA2094.

 

Has anyone priced the Ferrari filter vs. K&N recently? I bought my K&N years ago because it was $40 cheaper than the Ferrari one. Is it still like that?

 

Hi you all,
it seems, nobody really want's to learn something out of former threads.
I've mensioned before that it is important to keep intake air as cool as possible. Whatever filter you use, take a replacement and keep the airflow as original designed. The 308 ramairduct is an ideal one because it's sucking its air from outside the car instead of lurking hot air. But it looks like nobody cares for serious mods. And, to be honest, the guy's that can actually feel the difference in horspower are an practiceexample of soundsuggestivity to me. I tune cars for more than 20 years and never really experienced a difference in power by just feeling it. It's al measurable on the dyno and will give some positive figures. For the rest it is only the sound that gives the feeling. But keep in mind that a filter that forces the carb to suck hot air will never be an advantage. In fact it's a real dipper. But hey, who cares for quality.

Regards,
Marcel

 

I don't see how changing the filter within the stock airbox will affect the temperature of the intake air. The ramairduct does its job whether you have a stock, K&N or itg filter in it.
True, sound can give the illusion of power, however there's no doubt that a less restrictive airflow matched to rejetted carbs and a tuned exhaust do produce more power on these engines.
To me, the way the car feels is still the most important thing, afterall what defines the car's driving experience is how it feels.

Rocco

 

You've missed my point.
It has nothing to do with changing the temperature in this matter.
Wat I meant was that you should keep the stock airbox and use a replacement sportfilter with better flowcapacity. There are several manufacturers who can provide them. I use a K&N filter in the stock airbox because I can't gain any better than this. Removing the stock filterhousing and placing a couple of heatsucking sportfliters of any kind won't do any good at all.
Why did they use both air-intakes with a stocklike airbox on the Mchelotto's ?
Right, there was no better solution.
And further more, the feeling is important, off course, but how do you feel when a nice bill enters your mailbox for repairing damage on a overheated engine? Believe me, Ferrari has done his homework in this matter.

 

Did anybody in this thread suggest to do away with the stock airbox?

 

Some assume when you're talking K&N filters, the airbox is replaced with a cone type filter. Marcel, the K&N is a direct replacement for the stock filter within the airbox and has no further modification.
There was an article in Forza Magazine a while back that had dyno specs with K&N replacement (I think f-chat sponsor Carobu did the work) that showed insignificant bhp gains. I don't think any thread about K&N replacement has ever proven any significant change from replacing the filter.

 

Data point: on back-to-back dyno runs of my 60K mile '86 328, there was 5 rwhp difference between a dirty Ufi paper air filter and no air filter.

 

Dyno runs on my completely stock (before silencer removal) 308 carb airbox showed 6 hp between K&N and stock, and about the same between K&N and NO air filter. So to me, I wouldn't run out and get a K&N for an immediate hp boost, but just change to one at the next filter change. At least they will now just need routine cleaning and no filter replacement. I agree with everyone before that if you live in a dusty area, the paper filter is good. There is a small power difference with K&N, and they should be fine for most driving.

As far as airbox modification, there is a thread where we showed that the intake silencing on some 308 carb airboxes caused an obstruction, and it's removal allowed more air to the filter.

The cool air is the thing as Vetro stated and does make a difference. It's also been shown any effect of ram air overpressure is insignificant at road speeds.

Ferrari did improve on the single air box, going to twin plenums in the 348 and later to take advantage of the intake pulsing from the separate banks. I had a set of twin aluminum plenums made for my Webers to take theoretical advantage of the same effect, ducted to twin K&N cones. I then opened up the side vent and placed a large aluminum duct to route fresh cool air not only to the filters, but to cool the carbs, as I have had some fuel issues on 100+ degree weather here in Texas. I am not saying these are definitely better as I have not dyno tested them, but are better in theory. I can say that I have not had the problem with the carbs in hot weather since the larger vent was placed. I can also say it's louder (not neccesarily good) and looks great (hey, that counts! ).

Airboxes actually have several other issues. Another is weather proofing - there needs to be a way to adequately keep precipitation and spray overload from the intake. I think Ferrari does not do a great job at this, at least in the Mondial series. Interestingly, when I was disassembling my intake vent, there is also a resonance chamber!

 

Ditto that in a TR, it was a VERY MINOR gain and not worth the bother considering the added HP due to KN also lets in engine harming dirt/debris! This is why i NEVER use the K&N for street. Please see my post above as to why i use K&N on track.

 

And that's my point to.
Thanks for your comment.
regards,
Marcel