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Old 11-30-2005, 02:31 PM
  #6  
britbrat
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Location: Deep River, ON, CANADA
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Default RE: 2 stroke VS 4 stroke

As with just about anything, there are lots of compromises to be made in engine choices.

Glo 2-strokes are generally cheap & make tons of power for their size -- that means that to get the best out of them you have to twist their tails pretty hard. For a given displacement, 2-strokes will outperform 4-strokes -- by processing a lot of fuel in a hurry. They prefer props that let them wind up until they squeek -- which sounds a bit odd in some types of aircraft. However, contrary to popular opinion, they CAN turn big props, but they just aren't doing their best work -- they run a little hotter than usual & you lose a bunch of potential HP -- dropping them down in output to that of a similar displacement 4-stroke, but without getting the nice sound & fuel economy of the 4-stroke.

Glo 4-strokes are costly to buy & usually cheaper to run. Because they don't need the massive muffler of the 2-strokes, they can actually be lighter in weight despite the larger number of internal bits & pieces. This is particularly true in the larger sizes. They don't rev like a 2-stroke & if you try, it will kill them as dead as a rock. They do turn a nice big prop, or a steep prop, quite comfortably. They sound neat in the right applications, but like the 2-strokes, they can sound silly in the wrong applications.

Gas 2-strokes are a bit different again. They usually don't like to rev like a glo 2-stroke, but unlike a 4-stroke they will survive occasional forrays into never-never land. They spin big props like a glo 4-stroke, but they burn lots of fuel --- which isn't a problem, since it is cheap gasoline. They are great for large-scale models
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