Ask a daft question - Air Filter

Ask a daft question - Air Filter

Author
Discussion

aarondbs

Original Poster:

845 posts

146 months

Thursday 2nd October 2014
quotequote all
I'm servicing the Swift Sport this weekend and will be doing filters and an oil change and my local Autosupplies Business in Chesterfield are pretty good. So, here is the, potentially daft, question. Would fitting a K&N filter or Piper or whatever make any difference whatsover to the car as opposed to a standard service kit part.


andy-xr

13,204 posts

204 months

Thursday 2nd October 2014
quotequote all
Yes, but not what they're sold for. I've worked this out, if you get the right aftermarket filter price, then look at the normal one, the aftermarket one is 'for life' as in, you'll get a good few years out of it vs changing it every service.

But, they need to have the right price difference.

A side effect of performance filters can be less restrictive filtering, which can actually mean less filtering. If you've got a turbo car, that's ace on autumn and winter mornings as you get better boost in colder air.


juliethotel

255 posts

149 months

Thursday 2nd October 2014
quotequote all
Some people would have you believe it'll give you a couple of extra horses - it's rubbish.

That may be true if the standard air box and filter was restricting air flow but they never are.

The only difference it would make is possibly add an induction noise, and with a K+N you'll likely never need to to replace it.

aarondbs

Original Poster:

845 posts

146 months

Thursday 2nd October 2014
quotequote all
andy-xr said:
Yes, but not what they're sold for. I've worked this out, if you get the right aftermarket filter price, then look at the normal one, the aftermarket one is 'for life' as in, you'll get a good few years out of it vs changing it every service.

But, they need to have the right price difference.

A side effect of performance filters can be less restrictive filtering, which can actually mean less filtering. If you've got a turbo car, that's ace on autumn and winter mornings as you get better boost in colder air.
Appreciate that. I did put a good quality, and rather large cone filter and pipework years ago on to my 164 Cloverleaf and the difference was noticeable at least in terms of induction noise. And we all know (much like the guy who was drilling holes in his exhaust) that if it sounds faster it is faster.

Impasse

15,099 posts

241 months

Thursday 2nd October 2014
quotequote all
There's negligible difference in airflow between a K&N type filter and a disposable paper filter provided both are at their optimum level of performance. For the K&N type this will mean regular thorough cleaning and oiling, for the disposable paper type this will mean replacing often and on time.

aarondbs

Original Poster:

845 posts

146 months

Thursday 2nd October 2014
quotequote all
juliethotel said:
Some people would have you believe it'll give you a couple of extra horses - it's rubbish.

That may be true if the standard air box and filter was restricting air flow but they never are.

The only difference it would make is possibly add an induction noise, and with a K+N you'll likely never need to to replace it.
I sort of figured this was the case but I am living in hope that someone will come along and surprise us all with a chart showing real increases in power from pick up to limiter!! Maybe someone from K&N or Pipercross or even Demon Tweaks.

theshrew

6,008 posts

184 months

Thursday 2nd October 2014
quotequote all
My experience is you probably won't notice the difference in performance although I've not fitted one for probably 15 years. Tech might of moved on since then.

The main difference you will notice is a quite pleasant Suuuuucccckkkkkk noise compared to a std box set up.

vtecyo

2,122 posts

129 months

Thursday 2nd October 2014
quotequote all
juliethotel said:
That may be true if the standard air box and filter was restricting air flow but they never are.

This isn't true.

aarondbs

Original Poster:

845 posts

146 months

Thursday 2nd October 2014
quotequote all
Monty Python said:
That is pretty, conclusively damning...

aarondbs

Original Poster:

845 posts

146 months

Thursday 2nd October 2014
quotequote all
aarondbs said:
Monty Python said:
That is pretty, conclusively damning...
or it was until you added more links..

Monty Python

4,812 posts

197 months

Thursday 2nd October 2014
quotequote all
aarondbs said:
That is pretty, conclusively damning...
The other links show increases in horsepower, so I'd sit on the fence and say that some cars may see benefits while others won't.

I'm a bit surprised at the gains - on a N/A engine the cylinder will take in a fixed volume of air, so unless the OEM air filter is actually causing a restriction I can't see how a change of filter would make any difference.

zeppelin101

724 posts

192 months

Thursday 2nd October 2014
quotequote all
Monty Python said:
The other links show increases in horsepower, so I'd sit on the fence and say that some cars may see benefits while others won't.

I'm a bit surprised at the gains - on a N/A engine the cylinder will take in a fixed volume of air, so unless the OEM air filter is actually causing a restriction I can't see how a change of filter would make any difference.
Pressure drop across the intake (not just the airbox) and exhaust systems always accounts for some horsepower loss.

I cannot imagine a situation where a drop-in filter is going to yield a noticeable increase in horsepower, or even a measurable one that is outside the realms of normal error.

aarondbs

Original Poster:

845 posts

146 months

Thursday 2nd October 2014
quotequote all
Monty Python said:
The other links show increases in horsepower, so I'd sit on the fence and say that some cars may see benefits while others won't.

I'm a bit surprised at the gains - on a N/A engine the cylinder will take in a fixed volume of air, so unless the OEM air filter is actually causing a restriction I can't see how a change of filter would make any difference.
Impressive to see 25HP from a cone filter. Something like an 8% increase would give the little swift 10HP.. probably noticeable. but a a decent install of one of these is say £400.

ChemicalChaos

10,393 posts

160 months

Thursday 2nd October 2014
quotequote all
Yes, the "performance" one will have a slightly better flow and thus liberate 2 or 3 more HP. But at what cost? These performance filters achieve the better flow by less stringent filtering. They are designed mainly for use in cars where the engine will be periodically rebuilt, so the larger amount of fine dust going into the engine doesn't matter. Putting one on a road car that will rack up many tens of thousands of miles on the same engine is a very bad idea.

This is what has happened to at least 3 turbochargers I've seen that have been running on K&N/Pipercross filters for around 50k miles.....





Do you really want this to be happening to your engine internals, just for the sake of a slightly more fruity noise and 3 more BHP?

liner33

10,690 posts

202 months

Thursday 2nd October 2014
quotequote all
K&N drop in filters are apparently worth 6hp on my 370z according to independent dyno testing , unfortunately thats less than 2% and cant be felt but made about 1mpg increase on average. I found the same on other cars as well , put it this way there is no downside to fitting a K&N

anonymous-user

54 months

Thursday 2nd October 2014
quotequote all
This business of "lasting forever" with a filter doesn't sit well with me. A filter that doesn't get blocked eventually is quite obviously not doing a great deal of filtering. I've always thought that they are at best snake oil and very possibly not providing as good filtration as a paper element filter.

Has any manufacturer at any level used one? What does the Bugatti Veyron use, or any other supercar? If the answer is (as I suspect) "a paper element filter" then I think it's a fair assumption they are the best tool for the job, unless you think Bugatti just want to "rob you with the servicing costs".

survivalist

5,664 posts

190 months

Thursday 2nd October 2014
quotequote all
The lifetime claim also isn't as cheap as it claims to be, as the manufacturers of these filters stipulate that you should clean and re-oil the filter at regular intervals. The cost of the cleaning fluid and oil is in many cases significant, meaning it's not cheaper than OEM paper filters anyway.

On the subject of these filters achieving their 'gains' through less stringent filtering, there seems to be a growing number of people who believe that they contribute to Mass Airflow Sensors as well. The theory being that larger numbers of small particles pass through the filter, which ultimately leads to the MAF getting dirty and needing cleaning/replacement. K^N obviously deny this, quoting all kinds of flow rates, particle sizes etc, but personal experience suggests their may be something to it - MAF started playing up within 5k miles of fitting a K^N. Cleaned the MAF and fitted and new OEM filter and 15k later still have no issues.

PanzerCommander

5,026 posts

218 months

Thursday 2nd October 2014
quotequote all
The only real advantage to using a K&N panel filter is the fact that it can be washed, re-oiled and re-fitted rather than having to replace it. If you buy new and run the car until its dead it will save you some servicing costs over the life of the car.

If you keep the car for a few years and then change its not worth the bother as it will cost you more (say ~£40 for the filter, oil and cleaner vs ~£20 for a paper element.

Which reminds me I need to wash and re-oil the cone in my Mustang (which without a retune does nothing but give you a slightly fruiter engine note) at some point in the near future.

C.A.R.

3,967 posts

188 months

Thursday 2nd October 2014
quotequote all
The only reason I'd upgrade an air filter would be for an 'open' type for extra noise - whilst accepting that I'll probably be losing a tiny bit of power too.

These panel types can't really gain anything, surely? The airflow must be dictated by the ducting / airbox shape and air feed from grille / bumper? Not the paper itself, which is merely there to prevent your car from snorting a load of crap which would give it a poorly tummy.

I remember selling on a 'TRD' branded one I 'found' in the airbox of my old Celica. Surprising how many enquiries I got when I was only going to throw it away. Think I made about £15 in the end and had a queue of people - but it was dirty and tired looking! Still, paid for my standard Toyota filter...