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If a side bonnet scoop is used with a cone filter...?

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Old 25 January 2003 | 01:08 AM
  #1  
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Dark Blue Mark
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From: Bournemouth - 5x Ex Impreza owner. 997 GT3 CS.
Question

Not a big fan of cone filters and the K&N is the only one I would consider, but... If it is used with one of the mini scoops, replacing the mesh grille, surely there would be a good air flow over it, thus reducing intake and underbonnet temps.

The design of the standard intake is pretty poor in my opinion. Would a well fed cone make any improvements? Or are they just crap

Just looking at the one on the P1 in Jap Performance magazine.

MB

Running with a TEK2.5 Dawes ans full de-cat at the moment.
Old 25 January 2003 | 03:59 AM
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The stock intake plumbing is amazingly restrictive even before you get to the air box, I think it's something like a 30 inH20 depression even before the filter element... obviously a cone filter will work somewhat better but would be drawing in hot air when the car is stationary. My solution was to make a new air box that mounts under the scoop, replacing the TMIC. This has three advantages... a) it always draws in cold air, b) it's less restrictive and c) it generates positive pressure when moving, allowing the turbo to operate at a lower pressure ratio and thus more efficiently Of course you do need to run an FMIC and reversed intake manifold for this to work

A simpler solution would be to make a divider that separates the engine compartment from the right wing area, with the air intake pipe going through it, allowing a cone filter to be mounted there without having the disadvantage of drawing in warm air when stationary, however it doesn't have the advantage of the positive pressure while on the move.

Cheers,

Pat.
Old 25 January 2003 | 11:48 AM
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Thanks Pat.

Not too concerned at the air when stationay as the only way to do this would be with a forced air feed. The standard box doesn't get any air at rest either, but I guess it doesn't get any underbonnet heat.

These are what im thinking of, with a deflector underneath, directing the air at the cone. As soon as you start moving, there will be cooler air going in.

(damn uploader not working [img]images/smilies/mad.gif[/img] )

I have some experience with filter design and modifications (on bigger machines that a car and think this should reduce the intake temp significantly.

MB
Old 25 January 2003 | 12:32 PM
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it will also let water get to the filter..

Dan
Old 25 January 2003 | 01:17 PM
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I have an APS 'cold air' filter that sits in the inner wing and get positive air pressure while on the move from my vent in the 01 bumper
Old 25 January 2003 | 09:31 PM
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I had exactly that setup. K&N fed by mini-bonnet scoop.

In really heavy rain on the M-way had a couple of boost-cut type events. Not nice. Either water-lock (doubtful) or some kind of extreme lean fuelling event. Now have standard grill sealed underneath. Removed the reasonator and the 2 openings in the wing feed the cone.........

I`m sure at idle there is a very slight misfire every so often. Could be down the cone?

Had this set-up on my 00MY UK for about a year, rain and all. MAF still fine (And it is one of the `weak` versions by all accounts!)
Old 26 January 2003 | 03:54 AM
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The problems in changing the stock intake are rain, heat and protecting the MAF sensor. Only the APS solution seems to address all of these issues satisfactorily (apart from Pat's idea, which sounds brilliant, if you're a DIY guy with lots of skill and knowledge). But that's me and 99% of you lot ruled out, then

Richard.
Old 04 February 2003 | 06:23 PM
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RB5Scott,

Have you actually measured the pressure after the filter and before the turbo to confirm that is gives positive pressure on the move? Sounds a little unlikely to me unless you have sealed pretty much all possible escape routes from the whole inner wing area to prevent incoming air escaping. iyswim.

Moray
Old 04 February 2003 | 08:45 PM
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Problem with the APS is that smooth 90 degree cast pipe reduces MAF voltages by about 0.3 V which can be incompatible with engine viability on some cars. It also gives historical MAF sensor codes on most cars it is fitted to. Not a huge problem, but also not ideal either, but I needed something to keep my MAF that would fit around the APS induction kit.

Put it this way, 550cc injectors (instead of factory 440) on my car with a fuel pump corrected the fuelling with a standard fuel map What I am saying is that all things being equal you have to add about 25% extra fuel to correct for this misread! I have confirmed this on wideband lambda.

If you are not custom remapping the ECU I would suggest a boxed off K&N with a cold air feed from the wing.
Old 07 February 2003 | 12:13 AM
  #10  
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Forgot about this post!

I'm not sure about the concern of water getting in, there are plenty of places it can do this, i/c scoop etc.

Some of the turbine filters I deal with have quite clever water knock out vanes, im sure id have no problem diverting the water
It would consist of an insert into the mini scoop, with some angled vanes, and a loop for water catching. Difficult to explain without showing a drawing, but it is possible! Im sure a piece of high micron mesh would help....

(might be selling the car now so not going to do it)

MB
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