Fuel filter in engine compartment?

[RandyAB]

I'm planning out my fuel system for use with my SDS system and was wondering if it were ok to mount the Holley post-pump fuel filter on the engine side of the firewall to keep it out of the tunnel? I can't find temperature range data on these filters. Any potential adverse effects to consider?

[Bevan]

Randy,

Based on a conversation I had with Airflow Performance when I was in your shoes, they strongly recommended against putting the filter in the engine area. You want to minimize fuel volume in the engine area and any potential for it to pick up heat before the engine driven fuel pump. This includes filters, gascolators, fuel lines. Any of these which must be FWF, should be protected from heat with fire sleeve.

Bevan

[RandyAB]

Originally Posted by Bevan

Randy,

Based on a conversation I had with Airflow Performance when I was in your shoes, they strongly recommended against putting the filter in the engine area. You want to minimize fuel volume in the engine area and any potential for it to pick up heat before the engine driven fuel pump. This includes filters, gascolators, fuel lines. Any of these which must be FWF, should be protected from heat with fire sleeve.

Bevan

Thanks Beven. With the EFI, the fuel pump would be in the tunnel before the filter.

[RandyAB]

Originally Posted by johnbright

SDS recirculates fuel to tank.

Ask Ross Farnham.

I will. I'm always bugging Ross with questions so I thought I would ask the forum first.

[Carl Froehlich]

Originally Posted by RandyAB

Thanks Beven. With the EFI, the fuel pump would be in the tunnel before the filter.

This is opposite of convention; filter then fuel pump.

Carl

[Toobuilder]

I have my off the shelf GM FI filter in the engine compartment. This is downstream of the pump just as with millions of GM cars with billions of hours collectively. I do have a pre screen to keep the trash out of the pump, but I think the main concern is protecting the injectors before the pump.

In my system, minimizing suction losses is paramount.

[RandyAB]

Originally Posted by Carl Froehlich

This is opposite of convention; filter then fuel pump.

Carl

There is a pre filter as well. In this case, two of them, one in each wing root.

[Ralph Inkster]

I have had great results with SDS systems with a filter ahead of the pumps, pump, and gascolator after the pump arrangement.

One instance we experienced- the Andair gascolator saved the day by catching debris from a failing pump before it could advance further thru the rest of the system. This arrangement made the situation very detectable prior to a total pump failure, unlike a closed filter that wouldn't have been looked at probably till the next annual, or after a failure mode.

[rv6ejguy]

With your pre-pump filters in the wing roots, you won't spill fuel inside the cabin when you check them. Not a bad plus.

There is no issue placing the post pump filter in the engine bay. As John said, we recirculate the fuel so there is no chance of heating the fuel up much like a non-return type Bendix FI system might.

Be mindful of extra restrictions before the pumps. We don't like to see gascolators mounted there unless they are your only pre-filter. If you must use a gascolator, using a high pressure one downstream of the pumps is the preference.

[charosenz]

Good discussion.

So my take from reading this and other discussions is that I am leaning towards, a 6-10u micron filter after the pump but inside the cab in the tunnel.
It took a while but I found WIX 33279 and BOSCH 71020 filters that have threaded ends in the 12mm-14mm size (not push on). Then a pre-filter in the wing root outside. Probably 30-100 micron.

I am still debating the option of a High Pressure gascolator. I do like the thought of being able to drain fuel to check for water. May be just "habit" from years of flying spam cans. But I also like the simplicity of leaving it out all together.

Comments welcome.

Charlie