David Brown wrote:Thinking back to when I was cart racing we only fitted trumpets to increase bottom end power and smoother acceleration i.e. for in the wet, otherwise we ran without for max power, using tiloson carbs on 100cc.
Dave
James Stewart wrote:So I presume then the smaller the engine the less of an advantage is gained from a trumpet. Would it make a noticeable difference on a 1.20 two stroke glow engine?
Chris Lane wrote:This not my area of expertise but I think we are missing a trick here. If an engine is designed to have a trumpet, and then is not fitted with one, there will be less than the intended airflow into the carburettor. This due to a phenomenon called the vena contracta. There is plenty on the web about it so I recommend a browse for those interested. A sharp-edged entry into a fluid channel is very rare so a trumpet seems to have an important function. For model engines I suspect that lack of a trumpet is only noticed at high power settings when the engine will want all the breath it can get.
Chris Lane
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