Enclosed Vs Cone Air Filters

[allye 530 3 Cars]

Hello all,

 

Seems fairly quiet around here so thought I'd ask one of those little questions.

 

As per the title, is one better than the other? Obviously that is going to depend heavily on every application, but for us old Peugeot owners with engine bays rammed to the max and hot engine bays what the best setup? For reference I'm taking about a CDA for example on the 309 with a V6.

 

This is also a great opportunity for anyone to post pictures of their air intake setups!

 

Thanks, Ali

 

(wooo, my 1st thread of 2014 )

Edited January 2, 2014 by allye

[Paul_13 212 1 Cars]

I had a Pipercross enclosed jobby on my 6 engine for ages and one day I thought of putting an open filter on just to see if it made any difference.

I was astounded at the difference!

Way more free flowing top end compared to the enclosed filter

[allye 530 3 Cars]

That's interesting to know Paul, CDA's are so damn expensive too, I also notice they are rated to different BHP figures which can't be a good thing!

I'm trying to establish a good cold air feed for the car, however I'm also worried about sucking up water where people put them down real low!

[GLPoomobile 958]

Any air filter, whether open or enclosed, will be capable of flowing a maximum amount, it's just that most suppliers don't state what it is. I know in the past when I've looked at universal filters from K&N and Green, that depending where you look, there is data available for maximum BHP that each filter is capable of. Clearly there are probably many people who have fitted cone filters to big power cars who have probably added a restriction because they don't realise the filter they've fitted is not rated to the BHP of their car.

 

Those CDA type filters are a good example. There are quite a few cheap copies around, and some aren't very big. No doubt people buy them becuase of the carbon "bling" effect and the good reputation, but the cheap ones are likely a load of crap on many cars.

 

In theory (I can't talk from experience as it's not something I've experimented with) an enclosed filter HAS to be better. Providing you have a proper air feed from the front of the car, you'll get a Ram Air effect when moving, so a better supply of cold air, and being enclosed means less heat soak and less hot air being drawn in at low speeds. But if the filter isn't up to the job, or there's a restiction in the air supply due to the layout/design, then of course it may end up being worse than an open filter. Given the packaging constraints of a typical 205 engine bay, trying to fit an enclosed filter that's up to the job is quite difficult. It's hardly optimum to have a black, metal filter housing sat at the highest point right above the exhaust manifold, yet that's what Peugeot had to do to fit it in!

[allye 530 3 Cars]

A few good points there GLP, my aim is of course a cold air feed, at current I'm undecided whether to have a enclosed somewhere along the hose of the feed or a cone at the end.

[welshpug 1,627]

Given that the standard filter is the same as used on the 220 bhp 405 T16, i doubt the original 205 unit is restrictive.

[Mac Crash 78 1 Cars]

Given the packaging constraints of a typical 205 engine bay, trying to fit an enclosed filter that's up to the job is quite difficult. It's hardly optimum to have a black, metal filter housing sat at the highest point right above the exhaust manifold, yet that's what Peugeot had to do to fit it in!

 

Perfectly valid observation and I presume this is done to aid warm up by supplying the engine with warmer air from around the exhaust... I think we all are thinking cold air feed when we discard the standard filter box/drum and relocate the set-up usually to sit behind the nearside headlight with a cone filter, but surely unless the airfilter is directly in the airstream then it cannot supply enough cold air as the actual engine requirements in volumetric terms far outweighs what any ducting onto the filter can supply. Still it must be better than drawing warm air from around the exhaust. I don't know if placing the filter in the airstream disturbs the air around the filter and thus making it actually worse.

 

One other thing... I think something important may be overlooked (see David Vizard) regarding the inside of the filter cones themselves, ideally there should be a bellmouth to encourage the ram effect. Not sure if K&N cones have this, some I have seen do, forgot to check my one before fitting it.

[allye 530 3 Cars]

Another good point about the cold start, 205 TU cars had the little box that would draw air directly from the exhaust manifold, then a flap would change it to cold air feed. I'm not bothered about this being a summer car, also gets driven very gently when cold!

[GLPoomobile 958]

Ali, I presume you no longer have the battery in normal position up front. If so, is there much room in that area that you could use? If there's room, you could perhaps utilise an OE airbox from another vehicle and use the standard filter (or even an "uprated" panel filter) providing the donor car was of a higher BHP rating.

 

As an example, my V70 T5 has the airbox in the front passenger corner, with the intake coming in from the front by the grill, and the outlet (to my turbo, or in your case, direct to your throttle body) going diagonally out the back. In my head it seems ideal if there's enough space in that part of your engine bay. And with the T5 being rated at 250bhp the standard Volvo panel filter would be up to the job. I know you are eventually aiming for more power, and there are plenty of V70s running over 300bhp whilst keeping the stock air box with either a performance panel filter or a cone filter inside. That's just one idea that could be a cheap and easy solution.

 

But I guess the other half of the challenge for you will be finding a suitable space up front to provide the cold air feed. I'm guessing there's not much space.

[allye 530 3 Cars]

Great suggestion GLP and not something I had thought of, a possible solution for a OE look! At current the battery is in the standard position;

 

 

However! The new Clio engine has a larger inlet, so the throttle body assembly comer over further, meaning the battery will be going in the boot as there just isn't space. Moving the battery also give me options though, even considered taking the cold air feed around the back of the gear box! But again, this comes back to do I want it low down sucking up water. Bonnet vent/scoop really is out of the question.

[Batfink 201]

Once you get moving there is enough air flowing through under the bonnet you are unlikely to notice any real difference, other than an open cone will sound louder. The BMC is still quite loud though, but you will need to get the right size for sure! All filters are bhp limited. You need a big enough flow whatever the brand.

[allye 530 3 Cars]

Ok, so we can conclude there is no advantage one over the other, as long as they are both big/rated enough, just a cone is going to be slightly louder?

[GLPoomobile 958]

I wouldn't 100% agree with that. The only way you could draw that conclusion would be to do back to back testing on your own car, with the 2 different setups and using an IAT sensor. And also some preformance testing to make sure that even if the inlet temps are OK that the setup itself is not strangling flow.

 

I for one just do not believe that there would be adequate airflow under the bonnet of a 205 or 309 when moving. To my mind there simply MUST still be a lot of hot air trapped in there. There's no real provision for the hot air trapped under the bonnet to escape. Although I know some with track cars have monitored their IATs and reported them to be fine when moving. But a V6 in a 309 is a lot of engine in a small space, so really needs to be tested rather than comparing to an XU powered track 205.

 

Also, there was some articles done by an Aussie publication a few years back where they did testing of different home-brew indiction setups, adding bell mouths and ducting air from different parts of the front of the car to make a Ram Air effect, and they saw big improvements. Even the placement of the intake on the front of the car can have a big effect due to pressure differences at different points.

 

It's all theory though. The proof is in the pudding.

[Vili 17]

I had open cone filter under the bonnet at first. But when I did the mapping during the first summer I quickly noticed that the inlet temperatures were constantly very high. When the car was standing at the traffic lights IAT rose to 50-60C under half a minute and only came down to 40C or so when moving.

Then I did a little test, fast and crude as my product development professor used to say

This dropped the IAT to circa 40C when standing and to 25C when moving. So I did this. Still not very pretty but it does the trick.

[stu8v 68 1 Cars]

Dont overlook mapping, resonance and tuned length either.

 

I removed the std filter box and replaced it with a huge cone filter on my 172sport. It went flat as a fart, great noise but I lost loads of response and go....

 

Put the std assembly back on and it went like a rocket :-)

[allye 530 3 Cars]

As usual lots of different factors! As Sandy is mapping it and he also asked to be part of many of the decisions during the build, I'll run it past him.

[GLPoomobile 958]

As usual lots of different factors! As Sandy is mapping it and he also asked to be part of many of the decisions during the build, I'll run it past him.

 

Pft, what does that guy know?

[Biggles 65]

As usual lots of different factors! As Sandy is mapping it and he also asked to be part of many of the decisions during the build, I'll run it past him.

 

I could hazard a guess about what he'll say ... Based on my experience, it's probably worth taking his advice.

Edited January 5, 2014 by Biggles

[Spiky 37]

Many tests have proved an enclosed one with cold air feeds get better gains than an open filter

 

Heat soak is a power killer, so the last thing you want to do is suck in hot air

[engine killer 5]

Hi there, I am wondering will removing the rubber seal which is on top of the bulkhead/firewall (in front of the wiper motor compartment) be any help to allow the trapped hot air to escape? I have also seen someone raised the rear part of the bonnet up in order to improve the under bonnet airflow, but just do not know whether that will work or not.

I for one just do not believe that there would be adequate airflow under the bonnet of a 205 or 309 when moving. To my mind there simply MUST still be a lot of hot air trapped in there. There's no real provision for the hot air trapped under the bonnet to escape.

[welshpug 1,627]

Unlikely, as the area under the wipers is under positive pressure, also frowned upon in motorsport due to location of fresh air intake, not to mention looking crap

[GLPoomobile 958]

It's a safety no-no, and as WP said it won't help when moving (in theory). I think the only time it would be of benefit is when stationary as then the hot air will be able to escape a bit quicker.

[Bobbafett 49 2 Cars]

This could be useful, no?

 

http://www.ebay.co.uk/itm/190885992029

[Vili 17]

This could be useful, no?

 

http://www.ebay.co.uk/itm/190885992029

It could be useful if your airfilter is melting because of radiant heat. I doubt it won't make any difference to inlet air temperature.

[saveloy 8]

How about something like this?

 

Kyri