franky
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| posted on 7/9/10 at 05:18 PM |
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Air filters and BHP rating...
I'm currently looking for a airfilter with a 90mm flange size. Looking round some claim a max BHP rating for their filters(pipercross for one).
Just how accurate are these ratings? I take it they refer to a max airflow rate?
Are they worth going by? K+N don't list a max bhp for their filters though.
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mrwibble
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| posted on 7/9/10 at 05:26 PM |
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dont know how anyone could rate a filter for bhp without knowing the spec of the engine its going into...
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cliftyhanger
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| posted on 7/9/10 at 05:32 PM |
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it is just a factor of how much air they can flow. But of course I would cynically suggest they may be optimistic.
A decent sized filter should be fine. Just avoid wire gauze, socks an so on.
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interestedparty
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| posted on 7/9/10 at 05:49 PM |
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Funny thing about filter marketing, they'll tell you how well it flows, but tend to be reticent about how well it filters!
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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snapper
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| posted on 7/9/10 at 05:55 PM |
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As I read it, Pipercross have recommended max bhp For the size of filter i.e. Small for engines upto 130bhp largest for engines over 200bhp
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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twybrow
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| posted on 7/9/10 at 07:11 PM |
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When I bought my K&N they had a list of filters and their rated bhp figures... Look harder!
Here you go...!
[Edited on 7/9/10 by twybrow]
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franky
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| posted on 7/9/10 at 07:38 PM |
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 must look harder!
Went for an ITG one as I wanted a complete foam type 'cone' filter.
Just need to sort out a bit of pipework between the MAF and filter, I guess alloy tube will be better as it'll keep cooler than using silicone?
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twybrow
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| posted on 7/9/10 at 07:42 PM |
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quote:
Originally posted by franky
must look harder!
Went for an ITG one as I wanted a complete foam type 'cone' filter.
Just need to sort out a bit of pipework between the MAF and filter, I guess alloy tube will be better as it'll keep cooler than using silicone?
Why would it be any cooler? It is likely to be the temperature somewhere between the ambient air temperature and the underbody temperature. The
material won't make a lot of difference.
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franky
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| posted on 7/9/10 at 07:46 PM |
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I think I see what you're saying. So something like this will do for a connection between the MAF and where the filter is located under the
nosecone?
http://cgi.ebay.co.uk/90mm-3-1-2-Silicone-2-Py-Blue-Max-Air-Feed-Ducting-1m-/290366975845?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item439b386f65
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craig1410
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| posted on 7/9/10 at 08:27 PM |
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My advice is to stick to the reputable brands (K&N, Pipercross and ITG) and then choose a filter from a car of similar power output to your
intended application. You'll soon get the idea of size from the recommended applications list.
Note, one very important thing is to make sure you buy a filter which can accept a ram pipe. When I say ram pipe, I am referring to the little
bell-mouth air intakes which usually fit inside the filter housing. These force the airflow to take a curved entry into the carb or throttle body and
can be worth 5-10BHP on their own.
Also, with some of these you need to buy some filter oil with them otherwise they don't filter out the dirt.
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mrwibble
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| posted on 7/9/10 at 09:07 PM |
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quote:
Originally posted by twybrow
quote:
Originally posted by franky
must look harder!
Went for an ITG one as I wanted a complete foam type 'cone' filter.
Just need to sort out a bit of pipework between the MAF and filter, I guess alloy tube will be better as it'll keep cooler than using silicone?
Why would it be any cooler? It is likely to be the temperature somewhere between the ambient air temperature and the underbody temperature. The
material won't make a lot of difference.
i would suggest a shiny metal would reflect infra red radiation better than an a dark blue silicone tube. metal will also transmit it faster (cool
down) where as plastic will stay warm, it prolly makes v litte difference having said all that
[Edited on 7/9/10 by mrwibble]
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franky
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| posted on 7/9/10 at 09:13 PM |
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I've gone for the 2 ply silicone hose to connect it all, I'm going to make an ally backing plate for it too just to be sure and make sure
the filter is fed with fresh air by putting a duct on the side of the nose cone post IVA.
Cheers again all.
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