I have been in Rc boats for a long time, but still have a question. Do the velosity stacks work or is it better to run without? I have boats with and boats without. Just would like to find out from some of the engine builder with testing equipment if the stacks help or hender the motor performance.

Thanks for your time.

Randy

Not going to offer you DYNO testing results, but just a simple statement on what they do that is bad and good

Used in an engine like a stocker they will increase the engine torque a tad by making the total intake tract longer which creates a stronger ram effect.
However with this increased length it has greater flow resistance and can dampen the top end rpm a tad.

Used in a Modified engine with advanced intake duration, the ram effect of the charge in the intake tract is not as strong even tho flowing at a higher rate. The larger size of the modified intake tract & manifold can create fuel spit back issues, The use of a stack can actually increase the ram effect enough to take away most of this reverse flow spitback making the engine run smoother and carb stability better. The flow restriction is still present, but controlling the spitback issue and the power gained by doing so can in some instances be worth the addition of a stack.

No hard and fast rule, but understanding the dynamics involved allows you to apply this in your final set up.

Thanks for responding, I see what you are saying, and aware of the spit back you made reference to. I can see where controling this would help the motor be more consistant.

Thanks;