Fuel hoses size?

[isosceles]

What size of the fuel hoses are generally used in injection Lycomings? I have a AEIO-360 angle valve engine and recently realized that all hoses after the servo are -4AN. There is maybe a total of ~20 inches of -4AN hoses between the servo and the flow divider. Is this bad? I wonder if I need to replace them with -6AN hoses? So far i have not had problems with reaching take of fuel flow...
Thoughts?

Thanks.

[rocketbob]

4AN is the proper size from servo to divider.

[pazmanyflyer]

-6 from FI pump thru FW to mech pump, -6 from mech pump to servo, -4 from servo to red cube, -4 from red cube to spider.

[isosceles]

Thanks a bunch!

[cajunwings]

For comparison, Piper Saratoga with 300 Hp IO-540 has -4 size lines from Servo to Fuel Flow Sensor to Flow Divider.

Don Broussard
RV9 Rebuild in Progress
57 Pacer

[agent4573]

Originally Posted by cajunwings

For comparison, Piper Saratoga with 300 Hp IO-540 has -4 size lines from Servo to Fuel Flow Sensor to Flow Divider.

Don Broussard
RV9 Rebuild in Progress
57 Pacer

To take that further, on offroad buggies I've helped build, we used -6AN up to around 800hp on a full return boosted system (around 80psi). Above around 800hp, we stepped up to -8 for the primary feed/return lines.

You can use an online flow calculator and see that a -4 (0.25") pipe that's 3 feet long (approximate length from divider to injector) will flow .25 gallons/minute at 1 bar (14.7psi).

If your fuel pump is running around 15psi, you could conceivably support up to 60 gallons/hr flow rate before the -4 lines become the limiting factor.

0.25 gal/min * 60 min/hr * 4 lines per engine = 60 gallons/hr total flow rate.

[TS Flightlines]

Fairly easy to figure out------what size fittings were originally installed in the servo? -6 inlet, and -4 outlet MOST PROBABLY..
Tom

[isosceles]

I was just surprised that the sizes are different before and after the servo. Since they are -4, will those work?

https://www.holley.com/products/plum...ts/64191914ERL

With a fire sleeve installed, of course.

[TS Flightlines]

If you are comparing the OD of the hoses, 303 or any other rubber lined hose, vs a teflon assembly, THEN YES there is a substancial difference. The ID of the hoses are equal, but the construction of the hoses make the dimensions vastly different.

Tom