ditchlewis
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| posted on 7/4/08 at 03:30 PM |
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Air filter options - what are your opinions?
I’ve been reading all the threads that I can about performance filters and I’ve not got to grips with the pro’s and con’s of each type.
As I understand it there are two main types, foam filters and boxes such as K&N with wire like filters.
I get the impression that the box filters are the best and then foam and finally the carb sock.
Is this so?
And why?
The problem I have is space. I have 65mm from the face of the carb to the chassis rail which sits right across the centre of the carb mouth. I have
some K&N filters which came with the engine but they are 75mm deep and so won’t fit. If I get thinner ones then the air flow will be reduced (less
area) and therefore less horse power.
I have used carb socks, but one was blown apart in a carb back fire and luckily none was ingested by the engine.
The piper cross box for the pinto with 45’s is £200 and I believe it will not fit properly with out fouling the chassis. A lot of money to risk!
David J is making a filter for his bike carbs and that has got me thinking (I know a dangerous past time).
I had thought about making a box filter like the diagramme below with a cone filter on the end (80mm seems to be the diam that allows for up to 170
bhp).
The other alternative would be like the other diagramme, made of angle and mesh and covered in the foam type of material as David J.
What are your opinions..
Ditch
 
Rescued attachment box option 1.JPG
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ditchlewis
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| posted on 7/4/08 at 03:31 PM |
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here is the foam option
 
Rescued attachment box option 1.JPG
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ditchlewis
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| posted on 7/4/08 at 03:34 PM |
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ooops two the same, here is the box
ditch
 
Rescued attachment box option 2.JPG
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coozer
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| posted on 7/4/08 at 03:38 PM |
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I've gone for the box job in your bottom picture.
The outlet then goes to a BMC style air filter with a scoop in the nosecone to take cold air directly into the intake.
1972 V8 Jago
1980 Z750
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Mr Whippy
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| posted on 7/4/08 at 03:52 PM |
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get an old dyson, chuck the motor and stick a hose from your engine into the dustcollector outlet
Fame is when your old car is plastered all over the internet
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ditchlewis
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| posted on 7/4/08 at 03:59 PM |
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^^^^ is that an upright dyson or the smaller type? just happen to have a small dyson in the garage which won't suck .
my first plan was the air box with a remote filter.
why are the "air boxes" better than the foam sox?
ditch
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MikeRJ
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| posted on 7/4/08 at 04:34 PM |
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quote:
Originally posted by ditchlewis
why are the "air boxes" better than the foam sox?
Socks in general are a poor second best to a larger "sausage" style filter or an airbox that supplies all throttles since the area of
filter element that each throttle sees is far lower and hence more restrictive.
An air box will be quieter, it contains any 'stand off' from the carbs/throttle bodies, keeping it away from the filter element and it
means you can duct in a source of cool air rather than sucking hot air straight from the engine bay.
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twybrow
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| posted on 7/4/08 at 04:57 PM |
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I have option no 2. Seems a better choice to me....
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Eggy
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| posted on 7/4/08 at 05:32 PM |
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I've had a go at similar - have a look in my archive
Sorry, I can 't post fotos for some reason????
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snapper
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| posted on 7/4/08 at 05:34 PM |
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What ever system you go for, how much cold air you can get in will make a huge difference, i am currently running a domed pipercross 600 series, i
will cut side vents in the bonnet post SVA and when funds become available i will go for the pipercross airbox as it fits straight on the backplate
and has a built in cone filter then duct cool air from the front, this should be worth 5 to 8%.
Its worth remembering that you will not gain bhp persay its just that you are not loosing the full potential of your level of tune by sucking in hot
air.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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ditchlewis
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| posted on 7/4/08 at 07:31 PM |
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many thanks for the explanations lads.
i will go with my box option. i liked the idea of getting a clod air supply into the engine.
it's also easier to build.
should i use aluminium sheet folded or should i use fibre glass?
ditch
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twybrow
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| posted on 7/4/08 at 07:57 PM |
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I would think of how stiff you need the walls. Engines pull quite a vacuum, so as long as the aluminium is stiff enough to withstand the vac you will
be fine!
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NS Dev
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| posted on 7/4/08 at 09:04 PM |
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if it pulls that much vacuum then your air filter is MUCH too restrictive!!
There should be virtually NO pressure drop across the filter at full engine power.
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