Cone vs Dropin air filter

[2000StreetRod]

When I replaced my stock MAF sensor with a Lightning 90mm MAF sensor I also converted to a matching 4 inch diameter main intake tube and Spectre cone air filter.

I was concerned about the cone filter drawing warm air from the engine compartment unlike the stock filter that draws air from an opening behind the headlight. This morning I performed a data log to determine the impact.

The engine was cold started with an ambient air temperature of 74 degrees and the same intake air temperature (IAT). By the time I had backed out of the driveway a minute later the IAT had already increased to 78 degrees. I noticed from the data log that once the engine was fully warmed up the IAT would drop to about 3 degrees above ambient after driving above 35 mph for about 70 seconds. I also noticed that when stopped at a traffic light the IAT would steadily increase to 100 degrees in about 75 seconds.

There is a general consensus that for temperatures above 70 degrees, fuel economy and engine performance improves with a lower IAT. Since most of my driving is in the city I intend to revert to a dropin air filter. Especially since I have two 1.75 inch diameter cold air intake tubes coming into the bottom of the stock air filter enclosure. But first I will have to modify the stock enclosure top to accomodate a 4 inch diameter main tube. I will purchase an Amsoil filter element since tests show it to have high filtration with low restriction.

 

[Anime]

Newer Explorers with an intake kit can use the location behind the passenger side headlight to fabricate a shroud to isolate the cone filter from the engine heat, and even use some ducting or creativity to channel the cooler ambient air to the filter.

Earlier Explorers with the battery in this location can't do this easily, and have even higher idle air temps getting in the system, but the impact of a cone filter on the system, even with the higher temps, can't be ignored. Once the vehicle has moved, and air is flowing through the engine compartment, the gains are again quite large.

I'd agree that a box type system is hard to beat, but it's hard to get a flat filter with even close to the surface area of a cone filter, so a cone filter usually comes out on top in the end, for flow and performance. For most people, a drop-in air filter in the factory box is just fine. You really need a cat-back exhaust to compliment a much higher flowing air filter/intake as well.

 

[IZwack]

But wait! It would be awesome to test out if the "warm air intake" concept works and if so, how it compares to "cold air". Most people just reroute the intake so that it picks up from near an exhaust manifold, like so:

 

[Anime]

It works, but only on vehicles with enough adjustment in the fuel system to allow for such an increase. The systems in the majority of assembly-line vehicles don't seem to, or at least not without some modifying/programming/tuning.

It probably also works a heck of a lot better on smaller engines in much lighter vehicles that don't need a lot of power/torque from the powertrain to get going...but it might work great on a larger vehicle if such a system could be enabled once at highway speeds.