small lines do not provide enough fuel at high altitude
over 20K the engine will quit when switching tanks
unless you use high boost
go ahead and use the large diameter lines to prevent that
IV-P 500 hrs
From: Dan & Kari Olsen <olsen25@comcast.net>
To: lml@lancaironline.net
Sent: Mon, December 5, 2011 1:38:22 PM
Subject: [LML] 3/8" or 1/2" Fuel Lines?
LML Gang,
I’m building a piston IV-P and am near ready to close out the first wing. The kit I have came with 3/8” fittings for the fuel lines. However, I seem to recall some of you changing that out for ½” lines and hose.
What is the wisdom on this? Is the standard 3/8” sufficient or is ½” necessary? ½” is certainly going to have less losses but will also have more weight and will be more work and cost to swap out.
Dan Olsen
small lines at