Induction; air filters and stuff

[ben711200]

Evening all,

As part of the ongoing plan to make the Volvo go as it should when running on gas, it's getting a fairly comprehensive service in the morning. I'd be doing it now if I had a garage, I'm wide awake and in a car fiddling mood... A service for my car, being LPG, needs to pay particular attention to ignition components because gas is harder on ignition bits than petrol. So it's getting plugs, leads, rotor arm, dizzy cap etc.

The other thing that needs sorting is induction. It currently has Halfords Ripspeed cone filter thing that appears to have deteriorated somewhat.

The gas runs badly at the moment, and my induction setup is doing it no favours, so the filter is being relocated to be infront of the radiator (not directly infront of it, but further forward in the car) so it gets cold air and increases the length of the inlet tract. It's really short at the moment and it needs to be longer as it apparently helps it draw better.

But what filter? I imagine I'll be chucking the rubbish one back on as a temp measure, but I could really do with a new one. But what sort to get? Do I really need to splash out on a K&N? How exactly are they so much better than a cheaper equivalent? Any recomendations?

Cheers

Ben

[will]

Fella I know dynos bikes and he reckons foam FTW, I'm no expert but seems to make sense that a oiled foam filter will have more suck than a paper type one.
Feel free to flame me on this one though

[mudbitz]

same thread but can someone elaborate on inlect tract and getting it right in terms of length
run an extended inlet on my snorkel on my vitara so very interested in opinions please

[ben711200]

A foam one does make sense, thanks. It does confuse me though. There's a lot of rubbish spouted when you search for air filters and induction kits..

[Lewis]

Stock paper filter and housing is usually best if you can get it......or at least, stock housing with a drop-in aftermarket filter like an ITG.

Not a fan of oiled filters - tend to clog stuff up, and the cost of the filter and re-oiling kits usually outweighs that of about 30 stock filter changes Rather change the OEM item more frequently.

Seen many back-to-back dynos where filter has made no difference too (on modern stuff, at least) - and in some instances dropped power - especially those that are 'cone' style....

[will]

Foam = wash it when needed + re-oil.

Any mx shop and poss other moto shops will stock filter oil, does not cost a bomb but you could use 2 stoke oil as it tends to be sticky too(have done this many times with the mx bike). Carefull not to use too much oil though it can lead to a right sticky mess.
I tend to ring um out then dab um down with paper towel, although really you should leave them to hang overnight but thats takes more organsiation than I've ever mustered.

Warning - when drying filters in a hurry, set the tumble dryer cool and put them in something so it don't make your clothes sticky

[ben711200]

Nov 22, 2009 15:36:50 GMT Lewis said:

Stock paper filter and housing is usually best if you can get it......or at least, stock housing with a drop-in aftermarket filter like an ITG.

Not a fan of oiled filters - tend to clog stuff up, and the cost of the filter and re-oiling kits usually outweighs that of about 30 stock filter changes Rather change the OEM item more frequently.

Seen many back-to-back dynos where filter has made no difference too (on modern stuff, at least) - and in some instances dropped power - especially those that are 'cone' style....

To be honest, that would be my preferred route, but all of the stock stuff must have been binned by a PO and I don't know how well it would all mate up with the extra LPG stuff. No harm in looking out for the bits at a scrappy though

[Fiat Daft]

does your car have an airflow meter? oiled filters and afm's don't really get on,16 valve vauxhall engines don't like induction kits either.

[Raoul Duke]

I'm sure one of the chavmags did an 'offisherl' dyno test, and airflow test, comparing various filter set-ups on typical hot-hatch. The results apparently proved the best option to be stock airbox & ducting, with a drop-in aftermarket K&N filter. I'd guess in most cases, the car's designers have already exhaustively worked out the optimum positioning/routing, but obviously production costs limit filter options to a cheap paper jobby.

[BenzBoy]

To be honest, (it all depends on the application) but the best thing to do is simplify the inlet tract, regardless of what filter is on the end of it. I think this yields the best results. Manufacturers compromise performance for MPG and quietness - if the air has to go through various sharp bends and silencers, it's not going to flow as well as something more direct.
I've had really impressive results just by creating a more direct route for the air to go.
A cold air feed will also be beneficial - no good having a simplified induction tract if it's huffing a load of hot air off the exhaust manifold! ;D

Frankly, I'm skeptical about a lot of these "performance" filters, particularly the ones that just slot into the OEM airbox. I don't see how they can make that much difference without other alterations such as simplifying the tract or opening up the air box to allow greater airflow.

I bought one of those Halfords / RipSpeed mushroom filter elements for a quid from the bargain bin, just to see if it's anything other than literally a disc of pretty coloured foam. To be honest, it looks just like a disc of foam to me...

[screech]

if its a hotwire maf then don't use an oiled filer, reasons fairly obvious.

go for a standard box with increased cold air feed, a smoothed simplified inlet path (matched gaskets, knife edged throttle ect) and uprated filter.

stick with that unless you plan failry wild tuning, and best of all it probly wont increase your insurance as much as an induction kit will. win-win.

[waveman1500]

Stick with a factory-style paper panel filter, they barely cause any restriction at all. As previously mentioned, cleaning up the inlets and outlets to the factory airbox will give you a much bigger improvement than changing the filter.

[ben711200]

Down to the scrappy + decent paper filter + more direct air it is. I had a feeling I'd be told that, which is the reason I have never bothered upgrading this kind of thing in the past. Except once, when I was 16 and the chrome air filter looked cool on my 1200 bug but it ran like poo!

Cheers for

[namless]

I wouldn't agree that the factory filters have not restriction at all.. using a panel filter would restrict the air intake however if you use one of them K&N panel filters they virtually no restriction in comparison to the paper filters. I was at one of the mechanic trade fare and K&N had a stand with a demo of the filters here is a link to a video (www.knfilters.com/video/KN_Airflow_Dem.htm) similar to the demo at their stand and it was amazing how much difference changing the filters made. even covering half the K&N panel filter with my hand the ball only dropped half way.

However like BenzBoy said it depends on the application. I personally have observed a difference,when I installed a BMC carbon dynamic air box (CDA) on my b200f to how the car responded in comparison to a factory air box with a paper filter, where as when I installed the same BMC it seemed to restrict the air intake on the b230et, changed it to the the K&N cone filter it was awesome. The panel filter in the factory box still seems to be restrictive compared to the BMC and K&N.

I wouldn't buy a K&N panel filter if I wanted to loose restriction because they seem to workout at nearly the same price as the K&N cone filters although if being used on a N/A car a cold air feed is recommended you don't want it sucking hot air in the engine bay. The BMC CDA air boxes are slightly expensive.

If one wanted to go for a less restrictive filter at the cost of a cheaper insurance K&N panel filter is the way forward, I would 'never' buy a factory paper filter for my car again.