Outer Limits 4x4 Board

I am looking at getting a washable air filter for my Fez. What is your opinion on the best quality air filter in regards to flow and filtration. The options i have looked at are either K&N or Unifilter applications for the standard Feroza air box. Also the Unifilter pre airbox filter.

FROZY wrote:What is your opinion on the best quality air filter in regards to flow and filtration.

Paper

Seriously, steer clear of the foam filters. They let WAY too much fine dust through, particularly in offroad applications.

Stick with the paper filter. It has a large surface area and let's plenty of air through. If you MUST have more air, then take the back off the airfilter canister, remembering to put it back on when you're going offroad.

This isn't well known but genuine Toyota paper filters are water washable. This might also be the case for genuine daihatsu, they share lots of suppliers.

Steer well clear of K&N, unifilter etc on a road car. (i.e something you're not rebuilding the motor on each season)

Steve.

About the only constructive use of the coomon washable ( oiled ) filters is in precleaners IMO....

My main filter life has gone up significantly since fitting a precleaner - but its a frequent maintenance item.

I have been using a 2 Stage Unifilter for a couple of years now, and in MY case, the intake after the airbox has LESS buildup of particles than when using standard paper filters. I will continue to use it despite the tech experts saying they let stuff through.

The outer element gets filthy dirty, catching the majority of particles, as the inner filter has yet to be cleaned since new, as it has no material on it whatsoever. I'm happy with that.

I use a K&N on my commodore but wouldn't use one on an offroad vehicle. I use a Unifilter in the zook, they filter a little better than the K&N's and are used on motorbikes and quads so can't be that bad.

GRPABT1 wrote: used on motorbikes and quads so can't be that bad.

Not sure I'd trade the life expectancy of the average bike or quad for what you would reasonably expect from a car engine. Still perhaps we have different views of long life.....

Are you serious? Are you going to blame the life expectancy of a bike or quad on the air filter? FFS you guys are stubborn when you get an idea in your head. Ever used one?

Yes, I have used a finer filter and a uni filter. I got sick of cleaning them and everything around them. I acutally think most air filter housings stop working properly once these are fitted as the filters no longer shed dust.

I haven't personally used a K&N, but Isuzu Rover's tech on these is pretty damming.

Show me heavy equipment manufacturers that recommend a washable foam or oiled cotton gauze filter and I'll consider it.

To use motorbike/quads as an example of how they work well in protecting the engine from dust isn't a good example- these engines are rebuilt so frequently and are generally underfiltered anyway due to space restrictions- you just can't compare ring life (for instance) on a bike to a car or a low revving 4WD. It might not be down to the filter, but the filter probably won't be having anyhting like the effect on engine life it has on a car.

I've been right through this over the last 15 years since I started 4WDing, and I'm happy to stick with paper.

Steve.

GRPABT1 wrote:Ever used one?

Yes I have one in my road car and understand the compromise I'm making - slight decrease in restriction with a greater risk of contanimation.

I wouldn't make that compromise for my 4WD - its a different situation entirely IMO

IsuzuRovers information is easily available on outers but simply backs up every piece of research I've seen to date.

If by stubborn you mean "not going to ignore research" then yep i'm as stubborn as they come.

Well if your happy then yeah why not stick with paper, but if you're after a cheap couple of horsepower then it makes sense. My zook goes noticeably better with a unifilter than paper. I spoke a few swift people and they say the swift GTi motor is one of the most responsive to a high flow filter.

So far I have found my post filter intake to stay perfectly clean with the uni.

And I know how that sounds with my "seat of the pants dyno" and all. But it is the difference in top speed in 5th I measure it off.

That might be some evidence a stock GTI airbox is a touch small. IMHO if the car goes heaps better with a less restrictive filter then it might be a case for a larger filter body - which is what I am going to do. (with a paper filter)

I'm currently running a 1.0 airbox (all 660's run a 1.0 airbox in various configurations) and I plan to go to a 1980's hiace airbox - a very nice design like a little donaldson cyclopac - a much better design, and it should flow more air AND filter/seal better.

Steve.

I had a Finer filter pod type airfilter on my Feroza (about 6 years ago now) and I also fitted an outer "foam sock" over the Pod.

As far as particle filtration is concerned I dont believe it was any worse than the paper barrel type OE filter.

The car did gain a small amount of power.

But it did allow a small amount of the "filter oil" to be sucked through the throttle body.

I never bothered to investigate if that caused any problems with the MAF sensor or other relevant parts.

The car was traded before any effects on engine longevity due to this mod was identified.

rOd wrote: I never bothered to investigate if that caused any problems with the MAF sensor or other relevant parts.

The Ferozas use a MAP sensor, so no need to worry about the oil affecting anything.

Not wanting to hijack the post, but I tried removing the back of the filter box as suggested above (and previously) and was so impressed I drove home in 3rd . Are there any issues with leaving it off permanently for onroad? I guess there's not much risk of dust, but if its drawing air from the engine bay now is it gonna cause issues?

Thanks

It want cause any problem during some onroad traveling (bugs are bad) but after a lot of miles/kilometers you will have some injection problems in the engine and you will pay a lot of money and time to clean the inside engine from the dirt

I think you misunderstood... he just removed the back off the box... not the filter istelf.

I have a pod style finlter on mine, simply because I find paying $80 for a paper filter to be rediculous!
Show me somewhere that sells a feroza filter under $50 and I'll happily put the stock air box back in