Originally Posted By: Olas
Originally Posted By: dishdude
I want to know how what box does anything for power.
There are effects to increase the V.E on N.A engines. As with most tuning, this Intake tuning can be a compromise and only truly effective over a certain RPM range, but picking a choosing the design to fit in around the engine, the "boost" given can be used to smooth out the output over the engine.
Tuning can be done via the length of the intake runners, and their size. Long thin intake runners will speed up the gas velocity and the momentum of the fast moving air will help pack the cylinder full even as the intake valve is closing. This will boost power at lower engine speeds, but the thin runner design will restrict airflow at high speeds. Tuning and resonance of the pipework will also help.
As the engine sucks in air, there are pulses of high and low pressure. The tuning is designed use these pulses of pressure to get more into a cylinder, by adjusting the size and length of the intake. This effect is known as Helmholtz Resonance. The resonance effect will only work in a given intake size as a specific RPM range, so this can either be used to remove a flat spot, add extra torque in lower RPMs where most day to day driving occurs, or a variable length Intake system can be used to provide two resonant effects at different RPM ranges. An example of this is the BMW DISA flap in some manifolds.
Another is Ford's variable runner system they used on the 24V Duratech V6 and 32V Modular where "flaps" in the runners would control whether the air took the short route or the long route to aide in low end torque.
My question to you would be with respect to the OP's setup, how significant can the effect be when discussing variables in intake tract design significantly BEFORE the throttle body (where this resonator was, and well ahead of it) vs the rather obviously significant role of those behind it like the manifold design itself, and its variable runner brethren.
Somewhat answering my own question but BMW used tuned horns on the M5, one for each throttle body, which drew from a common (and massive) plenum that pulled from two large intake tubes that led to their own air filter assemblies. Obviously the horns were there to increase velocity and smooth power delivery at lower RPM's but I would doubt that the rest of the design past the plenum would have much of an effect, as most of it would be from the horns.
The throttle body itself is of course a regulated restriction and has a necessary effect on airflow. It wold also affect the smoothness of the air delivery, which would be most dramatic at lower throttle openings and be the least dramatic at WOT, which, IMHO, would be where anything upstream of it would have the chance to be the most effective.
IMHO, given the location of the OP's resonator, I can't see its contribution on the power side of things being significant. On the other hand I could see it reducing part throttle intake tract noise and, again IMHO, is likely what its role was here.
Great post BTW