tuner location

[johnab]

I can see very informative post for intake tuning on forum list & just follow up with one of the valuable reply by Rob 45 @ tuner location- "one can calculate the position of tuner" -

In othere words how does one can analytically calculate the location of quarter wave/helmoltz using hand calculation? Is it possible to calculate without dyno as the supplier would have limited access.

SAE paper/proper direciton would be appreciated

 

[GregLocock]

The optimum place for the quinkie or helmholtz, assuming you are aiming at a noise reduction, is at a pressure antinode of the resonance of interest. This can be found with a microphone. If it is a simple resonance of the intake this is likely to be at a position n/2 wavelengths from the end of the duct, I think.

But to be honest I've found that calculations only get you so far with air intakes.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[johnab]

Thank you for your reply,

But, would like to follow other things as well related to intake systems & hope if i get some confirmation:

Generally, quarter wave resonator design to fix the particular frequency. Just,consider the case like 250 hz is problem , hence the wavelength = 1170/250 so the length of the tube would be 14 inch.

(1) So does it mean that tuning frequency of the quarter wave would be 1000 hz? (As everybody know, frequency = sound speed / wavelentgh)

(2) If not what would be tuning frequency? (definitely the one you wanted to hear)

(2) The wave travel after half the wavelength will collide with the main wave with 180 out of phase but it would be in phase after the full wavelength & would be the superposition at crest instead of interference.

Doesn't it mean that qurter wave would decrease noise at half wavelength travel but will increase at full wavelength travel? Or,I am going in wrong direction?(tried to draw waves on paper & question did )

 

[johnab]

I did try to read some of the SAE paper & acoustic books,

"I would like to correct my self as the problem frequency (like 250 hz) is the one at side branch or helmoltz is tuned so when the problem frequency generates than resonator will reflect the same frequency out of phase & cance the noise."

I will really appreciate if Greglocock/Rob 45 or similar expert can confirm above statement?

 

[GregLocock]

I am not an expert at intakes, but yes, that is a better description.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[BayernHase]

I used to build speakers for homes and Jeeps. There is a publication titled "Speaker Builder". The equations given fall into line with your query. Google it.

Just for reference a speaker is a tuned enclosure comprising one or more drivers - not the/a driver itself.