CAI design, air filter out front or near the engine?

Is it better to put the filter at the head of the CAI or in an airbox near the engine? As I see it here are the pros and cons:

Filter out front - Pros: no need to worry about filter getting heat-soaked, entire intake tract stays clean, easier to minimize restriction with massive filter.

Cons: Filter will take the brunt of the dirt and get clogged real fast, exposed to more environmental wear.

Filter in the back - Pros: Heavy dirt won't reach the filter, easy to minimize restriction and heat with large/well-insulated/multiple intake tubes to the airbox.

Cons: Possible filter heat soak, need to clean dust out of intake tubing every now and then, more limited selection of filters/engine bay crowding.

Well if you want a CAI (COLD AIR Intake) then you wan the source of the air to be cold, not under hood air.

carguy123 wrote: Well if you want a CAI (COLD AIR Intake) then you wan the source of the air to be cold, not under hood air.

The source of the air would be cold in the two examples, the only difference is the filter location, not the air intake location.

Right, it'll come from the front bumper in any case.

It doesn't matter, the filter is going to get dirty, just one stays cleaner longer then the other. So, just how much maintenance do you want to do?

I a K&N drop in filter in the 318ti's airbox and ran ABS pipe down infront of the radiator for cooler air intake temps.

Really did not see the filter getting any dirtier than stock

Wherever it is easier to change.

mad_machine wrote: I a K&N drop in filter in the 318ti's airbox and ran ABS pipe down infront of the radiator for cooler air intake temps. Really did not see the filter getting any dirtier than stock

It shouldn't at all.......heck, before I got rid of my filter box, it had been swiss cheesed with a K&N, still clean when I removed it unknown miles later. I need to revamp this setup this spring.

What gets me is that most,maybe all,new cars have a cold air intake stock

Many of the so called cold air intakes (CAI) are not.

In reply to iceracer:

FWIW, the ion redline AEM shortram CAI even used the factory airbox and lower CAI........it was just a curved metal tube and a smaller cone filter, sure worth $200 eh?

iceracer wrote: What gets me is that most,maybe all,new cars have a cold air intake stock Many of the so called cold air intakes (CAI) are not.

the 318ti used a cold air intake stock.. but it was changed from the M42 engine to the M44. On the M42 it went directly forward of the airbox to a vent that pulled cooler air from in front of the radiator.

On the M44 engine, it used a corrigated plastic pipe that went up and over the cooling fan to the OTHER side of the radiator before hooking to a scoop that pulled cooler air from behind the grill..

I mostly emulated the M42 style (also used on the 6 cylinder cars) but used larger piping