Is there any design spec I should be working to when it comes to making my own air filters for my V6?
As I understand it, I can probably put a baseplate practically anywhere but how much clearance should I have from the end of the trumpets so as not to
affect the airflow?
As always any tips will be appreciated.
How about s foam sock over the end of each trumpet
Making airboxes the rule was a minimum of 1.5 X choke size. I suspect that with a filter you can go to a good bit less as the filter opposite the
trumpet will be flowing air as opposed to the airbox where all the air has to pass between the trumpet and the airbow wall.
If you've got room for 1.5 X choke then you are sure to be OK.
HTH
Cheers,
Mike
My trumpets are a bit unique as they are 'siamesed' on a twin port V6, so any filter will have to be quite a strange shape.
Image deleted by owner
Good grief you're going to have some fun making those trumpets. Have you not considered offsetting the pairs in a V to enable using a full trumpet on each port? Could be easier and probably better for flow?
They're already made - here's a pic of the finished version. The siamesed design was unavoidable due to the positioning of the ports and
length of the trumpets (they would otherwise have to be very short)
Components
They are on their way from Thailand as we speak ... er type 
and are made in a 'layer cake' construction so a baseplate can be sandwiched
between two layers (three in the trumpet part)
So I am thinking of having a foam filter on each bank something like this ..
[Edited on 26-11-10 by RazMan]
Looks like your on the right track to me, I've always been told that trumpet socks arn't that good anyway... (too close to the tumpets I
guess)
1.5x the choke sounds like over kill for a foam filter to me, I was going to leave about 1" on mine from the end of the trumpet to the inside of
the filter - someone tell me if this isn't enough !
Piper say 19mm min on there site....
I went for an ITG one for mine (had a lot of recommendations) and they come in more sizes than the piper ones too:
http://www.merlinmotorsport.com/Technical/pdfs/itgmf1.pdf
[Edited on 26/11/2010 by mcerd1]
Just had a (possibly silly) thought - what if I was to sandwich some fine mesh between the layers? I realise it wouldn't be as effective as a 'proper' air filter but it might stop anything falling into the inlets.
Just had another silly thought - I have my moments 
Is there any way that a sort of 'trumpet plug' could be incorporated? I mean something like a cone shaped foam filter which partially fills
the trumpet and is retained by some coarse mesh in some way.
Image deleted by owner
The reason I ask is that space above the trumpets is going to be very tight and any filter which is mounted on top of the trumpets (like the socks)
might give me clearance issues and I would rather not take a cutting wheel to my bodywork unless I really have to.
I made my own filter box and filter using scrap aluminium and filter foam from a local supplier.
Flat panel filters appear to be designed for a face velocity of around 1.75 metres per second. Work out how much air you car will draw in at full
revs in cubic metres per second and divide it by 1.75 - that'll give you the filter area you need. [There's 1000litres in a cubic metre, by
the way]
The foam I found is the same as that used in Unifilters, which is similar to the ITG's you have over there. The foam is restrained along two
sides by aluminium angles and is supported across the width of the filter by threaded rods [about 100mm apart] The whole thing was cheap as chips,
including the $Aus10.00 piece of foam.
Looks like this [crappy phone photo] :- 
and this with the filter in place :- 
Don't put anything near the trumpets. Even fine mesh will only be about 85% openings [the rest is the wire] and it will severely restrict
airflow, and create turbulence.
quote:
Originally posted by RazMan
Just had another silly thought - I have my moments
Is there any way that a sort of 'trumpet plug' could be incorporated? I mean something like a cone shaped foam filter which partially fills the trumpet and is retained by some coarse mesh in some way.
Thanks for the ideas guys 
Space above my trumpets is very tight so I need to make a very low profile filter, but keep it unrestricted. So if I made a foam sandwich around / on
top of my trumpets like this ....
Description
.... would that work? The backplate would be just below the trumpet flares and there would be about 20mm of 'free air' above them, with a
foam 'roof'. In theory air should come in from all sides and the top (although very close to the bodywork)
A couple of questions - what is normally used to stiffen the foam, stopping it from collapsing into the trumpets? Is it a coarse mesh cage of some
sort? I assume the cage is secured to the backplate?
[Edited on 14-12-10 by RazMan]
looks ok to me (not that I'm an expert), maybe leave a bit more room round the sides if you ca get it....
but isn't that just the same as a couple of low profile versions of these:
(they do very shallow versions
[Edited on 14/12/2010 by mcerd1]
[Edited on 14/12/2010 by mcerd1]
[Edited on 14/12/2010 by mcerd1]
that's how I did it
i glued the foam on the edges and it works ok, foam is stiff enough and doesnt collapse
For limited milage I'd be fairly happy running without a filter at all, I did it for ~4 years on a daily driver (not a performance car!) and saw no change in compression/performance in that time. I'm slightly more cagey with my turbo but still considering it despite it being against conventional wisdom!
Radom - That's a neat job but I notice you havent left any free space in front of the trumpets. Consensus suggests that at least 20mm is needed
to prevent any power loss. Definitely a Locost solution though
coyoteboy - I did consider running without a filter until one day I picked out a 15mm dia pebble that was lodged in the fuel rail (my trumpets are
pointing skyward) I hate to think what damage would have been done if it went in one of the trumpets! 
I have even considered tea strainers as a
temporary 'debris filter' until I sort out a proper filter.
quote:
Originally posted by RazMan
Radom - That's a neat job but I notice you havent left any free space in front of the trumpets. Consensus suggests that at least 20mm is needed to prevent any power loss. Definitely a Locost solution though
coyoteboy - I did consider running without a filter until one day I picked out a 15mm dia pebble that was lodged in the fuel rail (my trumpets are pointing skyward) I hate to think what damage would have been done if it went in one of the trumpets!
RazMan - have you got the dimensions of your setup worked out ?
quote:
Originally posted by mcerd1
RazMan - have you got the dimensions of your setup worked out ?
I might be able to squeeze a 60mm tea strainer over each trumpet with a bit
of creative cutting & shutting to get the right shape but you get the idea... 
so your going for the cossie DFV look then
I take it plan E (cut a hole in the bodywork) isn't an option on your car them....
[Edited on 14/12/2010 by mcerd1]
quote:
Originally posted by mcerd1
I take it plan E (cut a hole in the bodywork) isn't an option on your car them....
Trumpets work by letting the air flow in from all sides around the radius at the mouth and then into the tubular part. Ideally, the air accelerates
gradually and smoothly from stationary [away from the trumpet] to the maximum at the throttle blade.
While the tea strainer idea is pretty natty, it defeats the purpose of the trumpet lip - if you have to go that way [with mesh], do it like the cossie
above.
Do the sums on the free area of the mesh too [that's the actual area of the holes compared to the total area of the mesh] - in many cases it can
be down to 50% i.e. for a square inch of mesh, you only get half a square inch of holes for the air to flow through.
The trick is to keep the velocity through the mesh as low as possible ..... as the resistance to airflow is proportional to the velocity squared.
More resistance = less power.
You are absolutely right there Rick so the tea strainers are in the bin now
I'm just weighing up the pros and cons of going for either ....
how much time can you afford to play around with it on the rollers....
quote:
coyoteboy - I did consider running without a filter until one day I picked out a 15mm dia pebble that was lodged in the fuel rail (my trumpets are pointing skyward) I hate to think what damage would have been done if it went in one of the trumpets! I have even considered tea strainers as a temporary 'debris filter' until I sort out a proper filter.