We received many letters asking which high flow air intake systems to use.  We decided to test a number of manufacturers' systems to determine which system was superior.  We tested each system and found systems manufactured by aFe (Advanced Flow Engineering) were the BEST by far.
     Diesel engines use seven times more air than gasoline engines of equivalent size so clean cool air is a must for extended engine life, better fuel economy, and additional power.  A higher flow of intake air coupled with a high flow exhaust system allows for more power, a better fuel economy, extended engine life and reduced exhaust temperatures.  On the other hand ingested dirt through the air intake system becomes Silicon in the engine oil, which is a harsh cutting agent and can damage your engine quickly.
     We tested three very popular systems.  I will not mention the names of the other systems as a courtesy, but I will explain what problems we found with them.  We evaluated the systems by a number of criteria, filtration protection, flow, design, ease of installation, and cost.  Almost in the beginning of the tests we realized in most instances a new intake system was necessary to achieve our goals.  We needed a kit that used mostly outside air and not hot engine compartment air.  We decided to use systems designed to use mostly outside air.
     Two manufacturers claimed their systems delivered cleaner air at a higher flow, but this was far from the truth.  We did not believe any of the manufacturers' claims and tested each system by operating the vehicle 3,000 miles and performing an engine oil analysis performed at every oil change so they had a Silicon number of three (3) to base their tests on.
     The first manufacturer's system was fairly easy to install but we had problems with the oil used to coat the filter also coated the Mass Air Flow Sensor causing a service engine lamp to come on.  I called the manufacturer but they had no explanation as to why this should happen but they had this complaint before.  Through the three thousand mile test I had to clean the sensor three times to stop the service engine lamp from coming on.  When the oil analysis results came back, is was discouraging with Silicon levels at eleven (11).  I almost could not believe the result, so we changed the oil and filter and repeated the test.  The results were almost the same eliminating this manufacturer quickly.  I contacted the manufacturer to discuss the results and they were not helpful and basically said, "what you see is what you get"!
     We installed the second manufacturer's system again changing the engine oil and operating the vehicle for three thousand miles.  The first problem we encountered was the service engine lamp coming on and I thought the oil they used was coating the sensor again.  I removed the sensor and found some oil on it which I cleaned off and reinstalled the sensor.  Within ten miles the lamp was on again.  I removed the sensor but there was no coating of oil on it.  I then placed our scan tool on the engine and quickly discovered the airflow rate was too high for the sensor.  I then realized the manufacturer had moved the position of the sensor into a higher airflow and velocity position trying to squeak a little more power from their system.  I continued the test having to deal with the service engine lamp throughout the test period.  The engine oil analysis gave a Silicon reading of eight (8) and along with the engine lamp problem did not give the manufacturer high mark but I felt if I discussed the problems with them, maybe we could overcome them.  I placed four calls to the manufacturer and I am still waiting for a call back!  This surely eliminated this manufacturer.
     The third manufacturer we tested was aFe (Advanced Flow Engineering).  We used their Magnum Force air intake system.  We operated the vehicle for 3000 miles and when the oil analysis came back it was promising with a Silicon reading of five (5).  While five was the best Silicon result we had, it was not good enough.  I called aFe and was pleasantly surprised when I discovered they were truly concerned.  I spoke with a Mr. Paul Hardley who suggested I try their Pro-GUARD 7 media they were about to release.  He explained the new Pro-GUARD 7 media was five layers of progressively woven synthetic polyester fabric with random porosity.  The filter media is sandwiched between two layers of aluminum wire mesh.  He agreed to send two Pro-GUARD filters for a new test.  I installed the Pro-GUARD 7 filter, changed the engine oil and operated the vehicle for three thousand miles.  The engine oil analysis was excellent with a Silicon reading of below three (3).  Finally we found an air intake system that gave us a higher flow rate and better filtration.  The aFe Magnum Force air intake system is a well-designed system, easily installed and uses about 90% outside air.  The filter is cleanable and the oil used to coat  the filter is patented because it is formulated not to affect the airflow sensor.
     Another positive factor of the high flow system was the fuel economy increased about 1/2 MPG in mixed driving and 1 MPG during highway tests.  The filter media used by aFe will not collapse if it gets wet of subjected to high boost pressures.  They also offer pre-filters for most of their applications for very dusty or dirty operating conditions.
     A very important factor in this test was the manufacturer was willing to discuss problems with their products and help to overcome them.  My hat is off to Paul Hardley and all the people at aFe.

Dan Montegari
President
Precision Diesel Services, Inc.