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Old 04-09-2002, 08:54 PM
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Default Don K Fuel Facts

I take exception to Don Nixes fuel facts when he states that 4 strokes need less oil than 2 strokes.

Here is my reason why I feel that 4 strokes need as much oil as a 2 stroke.

4 strokes actually run hotter in my opinion than 2 strokes because they do not have the cooling effect of the fuel vaporizing in the crankcase (latent heat of vaporization) before it is burned.

4 stroke engine bearings are not lubricated directly as they are in a 2 stroke (induction of fuel through a hollow crankshaft). 4 strokes rely on blowby past the piston ring for lubrication.

My hypothesis that 4 strokes run hotter than 2 strokes is supported by emprical data: 4 stroke heli engines all overheat in hot weather and 2 stroke heli engines hold up fine in helis regardless of outside temp. This is why 4 stroke heli engines aren't popular though a 4 stroke motor would be better suited for a heli than a 2 stroke in maintaining constant rotor rpm over various loads imposed by the rotors system.