air filter size

Seight-V8 · Post by **Seight-V8** » Tue Jul 13, 2010 6:48 pm

hello all,

So my current air filter is a cone at 115mm large diameter & 90mm small diameter by 150mm long....

All this on a tuned 4.6 v8...somewhere between 280-300bhp...

looking to get a new one....but how do i know what size will be enough?

been looking at some cold air feed kits also...that might help keep drawn in air cooler.

cheers

scott

kiwicar · Post by **kiwicar** » Wed Jul 14, 2010 6:41 pm

Hi,
the important things to have are a good entry into the pipe that feeds the plenum, ideally the pipe wants to be tapered about 14% of it's diameter/ foot length and be flared into a bell at the end with a radius about 1/4 the radius of the pipe. If you have that then on a K&N type filter the curtain area ie the bit that is actually filters should be at least 4X the area of that of the pipe just before it forms the bell. If the pipe is not tapered you need a bigger radius bell (though pipe will still be a restriction) and you can have a smaller filter as it won't make much difference.
Best regards
Mike

bigaldart · Post by **bigaldart** » Thu Jul 15, 2010 6:08 pm

An enderle injector with 3" x3 circular butterflies will flow 3500 cfm, just for comparison. I imagine you have more than enough filter area for a Rover V8.

Alan

Ian Anderson · Post by **Ian Anderson** » Thu Jul 15, 2010 8:15 pm

My suggestion would be to call K&N in the UK

Ask nicely and advise you need to be able to select from their filters but need it not to restrict the air flow for your HP number

They will either a) Send you a list of HP ratings to their part number or B) if you are even luckier advise you on what would best fit and work.

After that ask them for a local supplier who has thet part number in stock

Certainly worked for me.

Your dimensions look similar to my filter but mine is slightly longer
They advised not to use on an engine that could produce over 300hp so your filter I would think would be restrictive

Ian

richardpope50 · Post by **richardpope50** » Fri Jul 16, 2010 1:20 pm

I had the same question and if you look around the web you can find out what BHP ratings each is rated at - except the standard car accessory kits marketed to everyone. In the end I bought a Pipercross. They have a huge listing.

stevieturbo · Post by **stevieturbo** » Fri Jul 16, 2010 3:12 pm

K&N's website gives rough indications of power they support. As does Green I think.

Seight-V8 · Post by **Seight-V8** » Sat Jul 17, 2010 7:28 am

been thinking of a cold air feed kit, either from K&N or pipercross.

They both say up to 300bhp with 100mm air inlet pipe.

Hoping it may keep the air inlet temps down a bit from about 40-50degc.

As they engine bay is quiet hot and the air is been drawn in.

As they kits aint cheap, just wanted to make sure they will be ok.

scott