I guess what I am looking for is to not save money on glow fuel, or lose performance to duration like in a duration contest. I'm not looking for hours and hours on end, just 45-60 minutes of the same kind of performance you get for the usual 10 minutes on a sport ship, not wot throttle all the time, but not worrying too much about how often you use it either. So I am thinking a 24-32 oz. tank placed at the cg point with a perry pump/reg. Now for the engine. I have my eye on three of my engines, an O.S. 46fx, a Saito .72, and a Norvel .40 (just released). I'm sure the Norvel .40 would have the best duration, it's rated at almost the same power as a .46, and at 13 oz. it alone would make up for 4 oz. of fuel weight over a .46, and it is a dual needle carb, so it should work with the perry presumably. But Norvels are different and a little finicky at times, you just never know with them. Now between the OS .46FX and the Saito .72, I am taking a guess that fuel consumption would be about the same? In which case I would go with the Saito, as that would be an easier sound to listen to for such a long period, lol.