Performance Panel filters- Questions...

lukechad

lukechad

lukechad

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As I finally got to see my car in daylight last weekend I went about checking all the bits and bobs to make sure its all as i like it to be, oil level, tyre pressures, screenwash, airfilter etc etc. Just generally playing and getting familiar under the bonnet.

I took the airbox apart and the current filter looks like it could do with replacing, a gave the box itself a vacuum out to rid any crud from in there but still i think I need a new filter in.

What I want to know is reading on the net you can "de restrict" the airbox on these (basically removing the internal pipes of the box leaving a big area for the air to be passed through rather than it being pointed at one area of the filter. Also putting a K&N panel filter is said to improve throttle response with higher airflow through the filter.

Now my questions really is this, is the K&N, or other makes worth looking into as a replacement, they are perhaps 4x the price of a standard paper type one but they are washable and re-useable. What i'd also like to know is if there is any lab tests to show how much more airflow is possible with a sports filter over a standard one, I was hoping for a percentage airflow increase as a figure.

Basically im trying to justify the money if people feel they are worth the cash.

Babbling over.....
 
"de-restricting", depending on the airbox design, has a tendancy to mess up the venturi action of the air intake and actually decrease the airflow. So I wouldn't bother with that.

Some people argue performance panel filters are better, then some argue the other way - the only thing I will say is screw the K&N and look at BMC or Green panel filters if you're going down that route
 
you lose the venturi effect if you remove the venturi stack. keep that

as for filters, im really not a fan of K&N. you can see through them quite easily... it is meant to be a filter

stick to paper or foam
 
Toker said:
"de-restricting", depending on the airbox design, has a tendancy to mess up the venturi action of the air intake and actually decrease the airflow. So I wouldn't bother with that.

Some people argue performance panel filters are better, then some argue the other way - the only thing I will say is screw the K&N and look at BMC or Green panel filters if you're going down that route
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Thanks mate, 2 new names to me there! I will look into them! Its hard to explain the layout of the insides of the airbox without a good diagram but I wasnt going to bother with that anyway, it involves chopping up bits of pipe in the car and I dont want to be doing that anyway.

Thanks for the suggestions.

*EDIT*
What exactly is the "venturi" effect? Is it just the way the air moves inside the airbox? AFAIK the idea behind the removal of the tubes is to get a bigger bore on the inlet and outlet pipes.


Just checked greenpanel and they are more expensive than K&N and dont specifically do a filter for my engine size, the BMC do one but I cant find where to order for the UK, only USA and Canada!
 
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Green panel filters are grand though, why stop at a panel filter and go the whole hog and get an induction kit, also washable and will give any engine a slightly better tone without all the bass of a silly loud exhaust.
 
brendy said:
Green panel filters are grand though, why stop at a panel filter and go the whole hog and get an induction kit, also washable and will give any engine a slightly better tone without all the bass of a silly loud exhaust.
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because 99% of the time they don't work as well as a standard airbox with a decent cold air feed and panel filter :p
 
I heard and read that unless you go for the full induction kit with a cold box then things like the oiled K&N filters are only good whilst they are new and clean, so unless you're going the whole hog then stick with a normal cheap paper filter.
 
I had this puppy on my ST170. Sounded glorious. BHP increase doubtful, noise factor :D

DSCF0195.jpg
 
I was contemplating this a while ago. My conclusion- stick to standard filters and change them every 10k rather than every 20k as the service manual recommends.
 
Ditto, most aftermarket filters dont actually filter as well, thats how they get an increase in air-intake. Unfortunately, this means your engine is getting dirtier air than it was designed for. There are some makes (Apexi) that make filters that increase flow, and still filter well, but they cost more.

K+N = Krust + Noise
 
The benefit's of a K&N or similar filter over a standard filter vary depending on the engine. For example it makes a small but noticeable difference in general but soothes the 5.5-6k flat spot on the old CBR 600 lump I used to ride, again dyno shows that adding exhaust and filter added to BHP and Torque on a before/after session, the GSXR 750 was a lot smoother across the range and the dyno suggests it's making more power than stock, same story with the roadster only with better results (they left the factory in a highly restricted state). The Rav4 D4D lump however didn't get that much out of it even with a remap, fuel consumption did drop slightly though which if i'm honest was the main reason for the change on that (£400/month on fuel).

Have a read on a forums specific to your car and see what others with the same engine have found, it's not like you're spending hundreds on something you can't put back to stock in less than a minute.
 
Thanks for the suggestions guys!

Induction Kit- I tend not to consider them now as id rather have a nice flowing cold feed as opposed to a warm feed, pipercross do an induction kit with cold feed on it but its nigh on £200!

I think for now I will look about, see what other astra owners are considering. Im not really after the extra noise I just really wanted what was best for the engine. Seems paper one may be just that, as I didnt realise how poor K&N filters were for filtration!
 
you have to accept the filters role is to filter. a cone can give more power but mostly because boxes can be restrictive

my standard box has allowed me "20bhp" over standard

i like standard boxes, you can keep temperatures under control better that way
 
just put a blitz panel filter into my Corolla T Sport. make a bit more noise up top but cant really tell due to the noise from the solid motormount inserts i put in.

overall, getting a proper filter like an Apexi for instance can be all round better, more noise, more power, but also the potential for more heatsoakage, and cost...and more cost when you try and explain it to your insurance company!
 
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