Have just brought a ramair foam filter for the sensible car. Sensible car is 4.2 v8 audi with no major engine work making little over 300bhp. Filter is 150mm diameter at the big end, 100mm diameter at the small end, 150mm in length. So I make just under 700 square cm or 100 cubic inches which k&n says is big enough. It looks way too small to me - can someone give me a sanity check please
Bigger is always better especially as they don't stay clean for long
My theory..............4200cc engine at 6000 rpm is 25200000 cc per minute
Divide by 2 as its 2 revs per intake cycle makes 12600000 cc per minute or 210000 cc per second or 210 litres per second of air passing through the
engine.
210000 cc divided by the 700 cc volume of your filter means the air inside it will be replaced 300 times per second.
Is that theory and maths correct? Seems like alot of air, but i guess you need alot to make 300+ bhp.
Slightly OT but related..
even on a 2L at 7K tat is approx 120L/s
that is 30l/s down each ITB. Just makes you think how important flow really is at those sort of RPM as the max pressure is only 14psi!
Actually that is 45mph down each (45mm) ITB, not as bad as it sounds. Through a 3"intake to an airbox about 60mph. Some speed though, expecially
when it has to go through a filter. So yes, big sounds a good idea to me.
Should add, ramair and K+N different animals,the K+N has a convoluted surface which doubles (poss more) the surface area and is a petty free-flowing
material being single layer cotton. The ramair would need to be approx twice the size I reckon.
[Edited on 27/2/16 by cliftyhanger]
quote:
Originally posted by cliftyhanger
Should add, ramair and K+N different animals,the K+N has a convoluted surface which doubles (poss more) the surface area and is a petty free-flowing material being single layer cotton. The ramair would need to be approx twice the size I reckon.
[Edited on 27/2/16 by cliftyhanger]