4-Stroke Pumped vs. Non-pumped?
08-25-2007, 08:24 PM
#1
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4-Stroke Pumped vs. Non-pumped?
Hi all,I'm fairly new to the hobby. Been flying my PT-40 trainer and a big stik .60. Just bought a Hobbico SU-31 too. Eventually I want to buy a 4-Stroke and put it in a larger plane. I see you can buy 4 Strokes with a "pump" and ones without. My question is does someone like me who only flies on weekends and for fun NEED a "pumped" version? Or is a cheaper non-pumped engine good enough for what I need it for? I dont want to spend more money than I have to. What do you guys think? Any advice?
Thanks..Jester
Thanks..Jester
08-25-2007, 08:50 PM
#2
RE: 4-Stroke Pumped vs. Non-pumped?
In most applications you will be able to use a non pumped engine without any trouble. A pump will not give you more power either. A pump is normally used to solve fuel delivery problems, or in competitive aerobatic flying where you can't afford any loss of power due to fuel flow problems during violent manuvers. I have run several OS .91 four strokes without pumps, and one with a pump (factory pump). The unpumped run fine as long as the muffler and tank are used and installed properly. Both operate basically the same for the user, but the pumped engine had a lower more reliable idle, and solved a problem the pilot was having with a cowled inverted installation where the tank may have been too high.
Oh, and welcome to RCU.
-Steve
Oh, and welcome to RCU.
-Steve
08-25-2007, 08:58 PM
#3
My Feedback: (28)
RE: 4-Stroke Pumped vs. Non-pumped?
I have two planes with OS 120 (Pumped). I use them because they sound great less the muffler, just using the header pipe as an exhaust stack. Then again I fly where it can be LOUD. My Hangar 9 Mustang (60 size) sounds great coming across the field at 120-130 mph with the exhaust side facing you. A pumped engine would also be ideal if you were planning on running smoke in an airplane. No worries of fuel contamination from smoke, or smoke oil going back into your fuel tank. A pumped engine only requires a vent line to the atmosphere, not back to the muffler.
08-27-2007, 09:27 AM
#5
My Feedback: (8)
RE: 4-Stroke Pumped vs. Non-pumped?
A pump provides a consistent fuel flow throughout the flight. On non-pumped engines, as the fuel level burns off in the tank, the engine tends to lean out a little. If the needle is set properly, this won't harm the engine.
A great advantage of a pumped engine is that it allows you to place your fuel tank wherever you want (on or ahead of the CG). I like to place mine on or as near the CG as possible. That way there is no trim change throughout the flight as you burn off fuel.
A great advantage of a pumped engine is that it allows you to place your fuel tank wherever you want (on or ahead of the CG). I like to place mine on or as near the CG as possible. That way there is no trim change throughout the flight as you burn off fuel.
