I have had a number of e mails on this subject so info for all,some is quite basic.
As we know air density increases with reduction in temp(Charles Law) so where do we want the air intake to the filter?,in a cool air supply.Can we 'ram' it into an air box etc for more 'pressure' effect,yes but bear in mind a well designed scoop,ram duct etc will only give you around 0.5psi pressure at around 100mph!,the key is getting cool air into either an 'air box'or similar device then keeping it cool right into the engine(cool=high density=more hp)any pipe from the air intake via ducts,filters to the throttle body needs to stay cool,that means either insulation or materials that will not pick up heat from the engine compartment and transfer it to the air.Specific to the Zetec & Duratec air intake/cleaner systems some points to note.The size of the air cleaner volume on the 2.0 is 'on the edge',its volume just makes it,the 2.5 is around the same internal volume,too small for 'performance breathing',why?,because we couldn't get a bigger box in!,its that simple.So key points*Draw intake air from a cool,clean source*Keep it cool right to the engine*If you use an 'air box' type set up make it the biggest internal volume you can(put that bloody battery in the trunk I say!).Hope that covers it.I'll pen together some info on turbos as it seems we are all looking for a 'bolt on',to get a worthwhile turbo set up a lot of factors have to be acessed.More to follow.Regards to all.TAH
