Homemolded Velocity Stack

Discussion in 'General Questions' started by ElMicNip, Oct 30, 2010.

  1. ElMicNip

    ElMicNip Member

    I was wondering if there are is anyone with knowledge of velocity stacks. The weather is gloomy and I was reading forums and came across someone who made their own velocity stack and I thought I would give it a try. I cannot remember the name of the product I used to shape the stack (I had some in my toolbox), but it is the grey epoxy putty with the black core that you knead together. My query is this; is the shape good enough or do I need to square it off or level it off flush with the filter housing? First pics are the initial molding then I sanded for shape. I still have to do a final sand and some polish to see how smooth I can get the surface (less friction). Also I was curious about the principle of a velocity stack with no choke. Any links would be cool to save time in typing. Thanks in advance and any advice would be appreciated.

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  2. SimpleSimon

    SimpleSimon Active Member

    Here: http://en.wikipedia.org/wiki/Velocity_stack

    is a good basic explanation of the purpose and function of a velocity stack, and what gain (if any) might be expected across the power band of an IC engine. Frankly, on the tiny 2 stroke HT's, the quality of inlet port and inlet manifold casting is generally abysmal, resulting in severe boundary layer turbulence in in-flow. A much better improvement can be realized by properly porting and polishing both inlet and exhaust system components, and matching porting.