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I was looking on ebay the other day as i need a new gear knob for my '98 Primera when I saw loads of 'K+N' type air filters for sale. All proclaiming more power and improved fuel economy.. Are these claims pants ??? I thought they were just put on cars by silly little boys.. My car has 89000 on the clock and still runs like new, would it be worth getting one??
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Don't go there. Adam Going (Tune-up) will testify soon enough that the oil gunks up the air mass flow sensors rendering them useless.
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Mike Farrow
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Don't go there. Adam Going (Tune-up) will testify soon enough
... or do I mean Andrew Moorey? Or both? :-S
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Mike Farrow
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I fitted a K&N induction kit to my Celica about 15k ago, and while there is no improvement in economy or power, it certainly doesn't run any worse, but roars a bit more. Can get tiresome after a while mind!
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If you use a well respected make like a K&N then you should be fine - try nissanprimera.net - loads of users on there.
I have a 2003 P12 with a K&N panel filter - no better fuel efficiency, but better engine response at high revs - frees up the VVT on the P12 engine. An over oiled filter will cause problems with the MAF.
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The theory is that these K&N style filters allow better airflow. Better airflow equals more power!
However, in most cases the manufacturer will have optimised the filtration system to allow maximum airflow..
Most "add on" air filters are intended for a range of engines and thus won't have been optimised to suit your engine. At best they won't be any better than the existing filter, at worst they will cause a loss of performance.
Having said that, they do generally have the benefit that they are washable, meaning that they can work out cheaper in the long run.
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K & N - type air filters usually come in two forms
1) replacement elements, or
2) 'high flow' kits
Replacement elements are simply replacement filter panels of the K & N type that fit in your air box in place of the standard paper element.
High flow kits usually require removal of the standard air intake & filter box and (usually) a cone type filter is fitted directly onto the throttle body (or turbo intake).
Replacement elements can be a worthwhile buy since they are a one-time purchase and will last the life of the car. There is unlikely to be any airflow improvement and the noise damping of the intake system will probably still do its job.
High flow kits are likely to yield some improvement in airflow. Whether this will result in any more torque/bhp/economy will depend upon many other aspects of the engine / fuel / ignition system design. The main downside to this type of kit is a significant increase in induction noise. The location of the cone will probably mean the engine breathing in hot air (instead of ambient air), which will negate some of the airflow benefit.
Many (but not all) engine systems utilise a hot-wire type of mass airflow sensor. If the sensor is very close to the filter and you use an oiled type, then small droplets of oil from the filter can contaminate the wire and lead to fueling problems. This is more likely to be a problem with high flow type kits than replacement elements.
Probably the best way to find out if you're likely to get any power benefits from either type of kit is to contact the owners club for your make.
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