Questions on boost pumps for fuel injection.

[fabricflyer]

I was curious on the comparison of the EFII boost pump and the Airfllow Performance sold by Vans. Has anyone ever dealt with both of them? I like the sturdy frame, and low restriction of the EFII, but don't like the disposable filter used in it. It comes with a spare. On the other hand, the filter on the Airflow is a work of art and does a great job, just don't like the plumbing involved with the whole assembly.
Would like to hear thoughts on the two units by people have used them.

 

[terrye]

Precision Airmotive Injection Specs

I carefully read the filtration specs for Precision Airmotive's Injection system and neither the Airflow nor the EFII system met the spec. I ended up with a Weldon 18000A boost pump and a Falls Filtration O2W05847 filter/gascolator. Filtration rating is 17 micron nominal/33 micron absolute.

 

[Ironflight]

The beauty of the EFII design is that you can use whichever filter you want - the filter is not an integrated part of the package. I didn't use the disposables - I used a cleanable filter from another source.

 

[Don at Airflow]

Fuel filtration

This is from the Precision Airmotive Installation and Detail Specifications for the SilverHawk EX-5AV1 Servo Kit.

?Fuel Filtration: The fuel supplied to the servo shall be filtered to 32 micron nominal. This filtration may occur prior to the engine driven pump, but all other pumps and valves shall be upstream of the filter.?

According to this statement, any boost pumps or valves are to be ?upstream? before the 32-micron filter. This is so pressure from the boost pump can force the fuel through the 32-micron filter.

I disagree with the comment that ?neither the Airflow nor the EFII system met the spec?. I cannot comment on the EFII filter, but our Airflow filter is designed as a suction filter. This is to protect our electric boost pump. Therefore we use a 125 micron filter to prevent suction loss which may cause fuel to form vapor in some instances. Also since the filter is non-relieving, a finer filter on the suction side of the boost pump may clog easier causing a restriction to the flow, again causing fuel to form vapor. In our Airflow Performance fuel injection system, additional filters are not required in most installations as we have fuel filtration in the fuel control unit and the flow divider. Fiberglass or composite aircraft may require additional fuel filtration, but even in these cases the additional finer fuel filter should be after the boost pump.

Don