Paul,
I own and have flown several LA.40, FP.40, and LA.46 engines over the past 6 years so maybe my experience will help answer your questions.
Based on my experience with "STOCK" motors, I think the LA.46 has a little more grunt to turn larger propellers than the LA/FP.40. However the LA/FP.40 motors are no slouches. I've flown a kit-built Brodak Pathfinder (55 inch wingspan, 620 sq in area) in competition for 4 years with an LA.40 and this included some contests with winds blowing to 30 mph. I run most of my LA engines in a "wet 2 cycle". The LA motors NORMALLY come without boost ports, unlike the FP.40, and if a breaking 4-2-4 run is what you're after then you'll probably have better luck with the LA motor.
I've personally found that MY FP/LA.40 and LA.46 engines consume about the same amount of fuel. Several factors can cause a significant difference in the amount of fuel any of these engines will use to complete the pattern. IN MY EXPERIENCE, using a smaller inside diameter venturi, running in a 2 stroke mode vs a 4-2-4 mode, using a higher pitch or diameter propeller, running a fuel with a lower oil content, using a more restrictive muffler, or using shorter flying lines will all reduce the amount of fuel you need to fly a complete pattern. The experience of others may vary.
They all run fine on a 10/22 fuel (i.e. 10 percent nitro, 22 percent oil preferrably 50/50 synthetic-castor). The one exception is the older style FP.40 that has an iron/steel piston/liner. How do you know if your FP.40 is the old or new style? Look at the attached picture. The iron/steel engine will live longer with more oil (i.e. 25 percent oil and preferrably mostly castor). The LA engines and newer FP engines are of ABN (i.e. aluminum/brass/nickel) construction and run fine on less oil.
Hope this answers your questions. Keep your lines tight.
DennisV
Topic: LA .46 vs FP 40 (Read 2884 times)