K&N Air Filters
Discussion
Im thinking of replacing the genuine air filter for a K&N one on my C4S as it state that due to its virtually unrestricted air flow while maintaining filtration levels is better then any other. Is this small mod worth doing and if so what levels of difference will it make to the engine power and the fuel useage
ad a K&N filter fitted along with a sports exhaust for my 968. end result was too loud and boomy for me and I was worried about all the internet chat re the filters letting crap into the engine. So had it taken out after 6 months and blow me down if the car didnt quieten down a bit - nice sporty note but not too heavy on the old eardrums. I noticed no drop off in performance having removed the filter and slept more soundly thereafter
I'm a bit mystified by the above comments. I have had my GT3 dyno'd on the same day with standard airbox and with K&N filter on. In K&N filter set up it produced 15 hp more. I have to admit, I don't have standard camshafts or standard exhausts. (any suggestions as to why are welcome).
Still, I have driven it mostly with the standard air box : the noise levels under acceleration with K&N filter are unplasant
Still, I have driven it mostly with the standard air box : the noise levels under acceleration with K&N filter are unplasant
maximu5 said:
I'm a bit mystified by the above comments. I have had my GT3 dyno'd on the same day with standard airbox and with K&N filter on. In K&N filter set up it produced 15 hp more. I have to admit, I don't have standard camshafts or standard exhausts. (any suggestions as to why are welcome).
Still, I have driven it mostly with the standard air box : the noise levels under acceleration with K&N filter are unplasant
Still, I have driven it mostly with the standard air box : the noise levels under acceleration with K&N filter are unplasant
That is complete rubbish, I don't care what anyone says a K&N filter will not give you an extra 15 brake, maybe it was late on in the day where temperatures were dropping or someone had changed cooling fan direction (could be various!) but there's no way you will gain that much. If any gains are made, I would estimate 5 brake and that is very max.
The problem with after market air filters is the laws of physics.
Standard setups have been designed with the correct air trumpets etc to generally gather cold air and have a very good standard of filtration with a good flow rate - to feed air to the engine with reserve and protect your engine from dust robbing the power.
Sticking an unmatched filter onto an engine is not very scientific, and often mismatched in several respects, usually in noise levels, flow matching, air column length (tuning), filtration quality, air source (quite often losing power due to warm air ingestion).
some cars will have poor standard induction systems, but certainly not Porsche, BMW etc.
Standard setups have been designed with the correct air trumpets etc to generally gather cold air and have a very good standard of filtration with a good flow rate - to feed air to the engine with reserve and protect your engine from dust robbing the power.
Sticking an unmatched filter onto an engine is not very scientific, and often mismatched in several respects, usually in noise levels, flow matching, air column length (tuning), filtration quality, air source (quite often losing power due to warm air ingestion).
some cars will have poor standard induction systems, but certainly not Porsche, BMW etc.
Those who say exhausts don't improve a 911 are plain wrong. Porsche put on restrictive cats to produce cleaner emmissions and mufflers to muffle the volume. Nothing to do with maximising performance. Ditch your cat or muffler and replace with the right update and you will notice better response, torque and often sound.
I have heard several inde dealers say don't bother, keep it original, but as someone who has done it (and many mates have too) it is definitely worth considering.
PS: The K&N filter didn't do anything for me though.
I have heard several inde dealers say don't bother, keep it original, but as someone who has done it (and many mates have too) it is definitely worth considering.
PS: The K&N filter didn't do anything for me though.
Some time ago I replaced the standard metal airbox and standard filter on a 911 Turbo 2 with a ZucZ Powerflo plastic airbox which came with a K&N cone filter as part of the package. Great induction sound and no apparent loss of performance and - given that the new item is plastic, of aviation quality apparently which I assumed to be marketingspeak - and lighter, performance is definitely going to be a bit better if only for that reason.
Cheers boys for your comments. Guess what I won't be changing anything hopefully for sometime as I don't need to go any faster and I certainly don't want the engine any louder, I run with a standard exhaust and am more than happy. Its just someone told me these were better and its a good thing to receive feedback as I will freely admit to knowing very little about what makes the wheels turn.
Comments about modest power gains for a filter alone are right in most cases, but the Porsche or BMW or whatever factory teams spending millions of development dollars on getting it right means they found the best compromise within their wide ranging criteria and with the median buyer in mind, not the best performance or the best sound or whatever to please a particular enthusiast with their own unique preferences.
"That is complete rubbish, I don't care what anyone says a K&N filter will not give you an extra 15 brake, maybe it was late on in the day where temperatures were dropping or someone had changed cooling fan direction (could be various!) but there's no way you will gain that much. If any gains are made, I would estimate 5 brake and that is very max"
This would indeed be rubbish on a standard engine with standard exhaust, but if you have changed the entire exhaust system to a much more free-flowing one and the camshafts were high-lift camshafts, the intake system can become the bottleneck. This seems to be the case with my car. The dyno readings were taken the same afternoon, at the same place, with the same petrol and the weather was almost identical. The chap who did the dyno reading says he sees great variability in the effect of K&N filters : from none to - in some cases - 15 hp, but only where quite a bit of the egine has een changed already.
This would indeed be rubbish on a standard engine with standard exhaust, but if you have changed the entire exhaust system to a much more free-flowing one and the camshafts were high-lift camshafts, the intake system can become the bottleneck. This seems to be the case with my car. The dyno readings were taken the same afternoon, at the same place, with the same petrol and the weather was almost identical. The chap who did the dyno reading says he sees great variability in the effect of K&N filters : from none to - in some cases - 15 hp, but only where quite a bit of the egine has een changed already.
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