Velocity Stacks

[Chris-PA]

Resonance tuning takes advantage of pulses that will reflect from any abrupt change in volume. To be effective one has to have a strategy where that pulse would be helpful, and the only ones that make sense here are to have the pulse that is created when the intake port opens get back just before it closes, or to have the pulse from the intake closing get back just after it opens the next time.

However, I really don't think you'll have much success getting a pressure pulse to pass through the carb from a tube opening on the outside. The venturi is quite a restriction, and the throttle and choke shafts are there too, so you'd get partial reflections off the venturi and all that stuff. It would be much better to create a resonance volume between the carb and the intake, but more than likely the size will be impractical, just like a pipe on the exhaust is too big for a saw.

Resonant exhaust and intake tuning is old tech, and free power, so if they are not doing it on stock saws there's likely a good reason for it.

 

[Terry Syd]

I remember a Chevy 283 that used intake and exhaust tuning. They got a volumetric efficiency of 104% on the engine, in other words, they had achieved a 'supercharging' of the engine. People were wondering how they could do that on a normally aspirated engine and then realised that part of the volume of the combustion chamber was being fed the extra 4%.

It would be a cool item on a saw to have the extra volume contained in the saw handle, simple and out of the way. It would be even better to have a valve on the extra volume to change the tuning like on some automobiles. Perhaps just a simple manual valve that an operator could turn and change the powerband for the particular work he was doing.

 

[Knot_Smart]

..................
Why not use what is naturally available to help the induction process...who says forced induction can't be used on a saw!lol

Another tangent, you made me think of all the air coming off the saw's flywheel as it spins upwards of 10K.......maybe just before the meltdown, all that air could do some good if it was stuffed down the carb's throat.
OK,....maybe not!

 

[Knot_Smart]

...........
Perhaps just a simple manual valve that an operator could turn and change the powerband for the particular work he was doing.

Not manual control via operator but this sounds like the modern automotive 2-in-1 intake plunums where sensor feedback helps the 'puter decide on which set of intake runners to use to feed the engine (one is short/fat one is long/skinny or some such).

 

[Terry Syd]

Perhaps the biggest problem on such a system is the fuel mix that gets misted into the system. On a bike the 'boost bottle' can be positioned above the intake and the misted fuel will continue to drain back into the intake. On a multi-position saw the 'boost bottle' could pool fuel and then when the saw was repositioned the fuel would dump back into the intake.

I don't expect it would be a problem once the operator knew how to handle it. He could just blip the throttle as the saw repositioned and clear out the fuel. For example, on a long back cut the fuel could pool and then as the saw was taken out of the back cut the saw could bog from the extra fuel in the intake. However, giving the saw a blip of the throttle as he removed the saw from the cut would keep it clear.