Introduction

The following is a test that I preformed October of 2002. The goal was to determine if an open filter element in the engine bay allowed hotter air to enter the intake versus the stock air box with the cone silencer in place. Due to all the controversy surrounding the cold air inductions systems sold and the design of aftermarket mass air meters, I felt the need to dispel some of the rumors regarding the two designs.

The Test

The test was conducted using the stock air box with silencer in place and with a C&L mass air meter with a K&N cone filter without the heat shield. One test was ran with the heat shield in place however it made no difference in readings and will not be part of the final result. Taking measurements for the test was a Radio Shack indoor/outdoor thermometer Cat number (63-1032). It has a remote sensor that I placed inside the intake track immediately after the mass air meter and then ran the display unit inside the car.

Three runs were made with each configuration with an idle period after each run. I drove one direction for five miles at 60 MPH turned around and drove 5 miles in the opposite direction. During driving there was no other vehicles in front of me to disrupt the air flow. (See below for details on steps I took to make sure I got accurate readings with the thermometer).

Results

Note: Stock means Stock Airbox/Meter/Silencer, C&L means C&L MAF with a densecharger TB pipe and NO heat shield.

At 60MPH.
With Stock the intake temps were 2* cooler over ambient.
With C&L the intake temps were 4* cooler over ambient.

At idle.
With Stock the intake temps were 50* HOTTER than ambient.
With C&L intake temps were 50-55* HOTTER than ambient. The readings varied more in this configuration than with the stock setup.

Conclusion

An open-air filter exposed to the engine does NOT heat up the air entering the engine; in fact the air is actually cooler when at any kind of speed. Not only does the open filter element cool the incoming air it also allows the engine to breath more freely thus requiring less work during the intake stroke, the less work the engine has to do intaking air the more power is available to the rear wheels. Ford designed the air box around a foam filter. The stock filter element when exposed like this would become dirty and clogged very quickly requiring frequent cleaning. One can only speculate that the design for the filter box is to reduce the maintenance required to maintain a clean filter. Since most of us now have K&N filters and clean then on a regular basis we can remove this restriction.

According to Dynojet research a good rule of thumb is that for every +/-10*F you can expect 1% loss/gain respectfully in power.

I hope some of this clears up the confusion regarding intakes. While I don't yet endorse the C&L MAF you can use your stock MAF in this configuration.

Note: The Radio Shack unit contains a "reset" button on the back of the unit. I could not determine if the unit averaged values over time to display a steady reading so instead of taking a chance I waited until I was up to highway speed and reset the unit. This ensured that the readings being taken were as accurate as I could get them with this equipment.

Below are some pictures of the setup as I preformed the test.