Intake/exhaust design: Acoustics galore!

[Electro]

Greetings all,
I'm here to start the grand acoustics debate. In design of our 2007 intake (and not to forget, exhaust), I focused primarily on acoustics. Obviously we have to have a pretty smooth flowing system too, as we're sucking a good amount of air.
However, because of our air-limited system, I tend to think great gains can be made by more focus on acoustics and acoustical damping.
So there's obviously a bunch of ways to approach acoustics tuning;
Runner length
Helmholtz (nice and pretty)
The engelmen method (which for the life of me I can't make sense out of)
Inertial wave ram charging effects
and I'm sure there are others out there

Net system effects
Helmholtz treating the system as a volume

So, I guess the purpose of this thread is to see by what methods you guys have approached the acoustic tuning of your engines (without divulging your top-secret plans), be it "calculate build and go" (our '05 approach), or maybe some testing in there somewhere; etc.

So now that testing has been mentioned, how do you all plan on testing this thing? Microphones, pressure transducers, left-thumb, one eyed guessing?

Additionally, my mention of "damping" was referring to having the system suck through the restrictor very smoothly. Meaning, since we're restricted (those evil rulemakers), let's use our restrictor as best as possible. Anyone have any research into how well your restrictor performs under fast transients? If the whole system is resonating, then aren't we sending pulses back and forth through the restrictor?

Thanks guys,
Happy Hunting of the ultimate flat torque curve


Electro Mike

[Jersey Tom]

Im wary of Helmholtz. I want to use microphones.

[Electro]

As am I Jersey TOM... as am I. I plan on using microphones, but where can you place them? If you plan on putting them inside the intake, they have to be small... small can't do low frequencies very well. So can we stick them to the outside? (High freq vibration screws us a little). As for exhausts... well, temps are a touch high for interior monitoring, so can we put them outside?

Thoughts?

But... We have to start somewhere... hence Helmholtz etc right?

[B Hise]

http://fsae.com/eve/forums/a/tpc/f/125607348/m/16210118...10118231#16210118231 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/16210118231?r=16210118231#16210118231)

search button

[Electro]

A further question to those who have done any acoustic tuning of their intake + exhaust. What frequency ranges have you observed (upper/lower). Have you seen many unexplicable high-freq harmonics? i.e. non-multiple of any of the lower fundamentals


Thanks,
Mike