Subject: 7.3-liter Ford OEM Air Filter Box Design Constraints
Communicate a problem with the design of Ford air
induction boxes on 7.3L-equipped diesel vehicles which leads to
premature air filter restriction gauge warnings when using EaA728 Air
The life expectancy of the EaA728 Air Filter is less
than the specified duration due to issues with Ford original equipment
manufacturer (OEM) filter housing design.
AMSOIL has documented problems with premature air
restriction on EaA728 Air Filters installed on Ford vehicles equipped
with 7.3L diesel engines. The problem appears via premature triggering
of air filter restriction gauges. In some cases, the problem is severe
enough to create performance issues, including lack of engine power.
A typical non-turbo-equipped 7.3L diesel engine requires
roughly 280 CFM air flow to comfortably perform without combustion
starving issues, including lack of engine power. A turbo-equipped diesel
engine requires 466 CFM air flow to avoid similar issues.
Another way to predict air-flow-related performance
issues is through a filter face velocity calculation. Donaldson Company
Inc.(DCI), a well respected filter manufacturer, uses this calculation
to measure the amount of air an engine requires for optimum fuel
combustion. A lower value in the face velocity represents better
performance. A face velocity of 7-10 is optimal for diesel-fueled
engines, whether turbo-charged or not. A Ford 7.3L OEM filter was tested
with this predictive calculation under both turbo and non-turbo
conditions. The results for were 47 for turbo applications and 19.48 for
non-turbo applications, both exceeding the optimal 7-10 design point.
This data shows that the stock OEM filter design is too small,
particularly in turbo-charged engines. As these filters become more
restrictive when contaminated with dirt, air starvation issues will
occur The solution is to replace the stock, non-cleanable air filter at
more frequent intervals. Ford now recommends that the air filter be
replaced at every oil change.(1)
AMSOIL Ea Air Filters are produced according to the OEM
specifications. Since these specifications are for a filter that is too
small, the AMSOIL EaA728 Air Filter is limited in its performance
capabilities, and its life expectancy is cut short.
AMSOIL INC., in conjunction with DCI, evaluated
aftermarket air filters, along with OEM air filters for 1999-2003 7.3L
Power Stroke diesel engines. The results of these tests showed a lack of
filtering surface area required by this model to perform satisfactorily
over the projected life of the filter.
AMSOIL recommends to continue using the EaA728 Air
Filter and cleaning at 5,000 miles or per restriction gauge. AMSOIL also
offers a WIX air filter (46728) but it cannot be cleaned and must
be changed per restriction gauge or OEM recommendation.
As an alternative to the factory designed filter system,
Ford introduced a retrofit air filter system called the Donaldson/Ford
Air Induction System (AIS) part # 2U2Z-9K635-AA/Donaldson part number
(X007953). AMSOIL offers this technology under part number (PCIS73). The
retrofit system is available for 1999-2003 F-250 through F-550 Ford
Power Stroke 7.3L diesel vehicles. The induction system is only
recommended for trucks that have not been modified.
1) Donaldson Filter Corporation, Personal Conversation
with Field Service Engineer and Account Executive.
AMSOIL Filter Look-up Guide and Cross Reference Guide.
Ford Motor Company, Service Advisor’s Guide. “ Selling
the 7.3L AIS Severe Duty Kit”
WIX Filter Lookup and Application Guide
AMSOIL INC., AMSOIL Bldg., Superior, WI
54880 (715) 392-7101 © Copyright 2003
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