Will Helmholtz resonator decrease power?

[Cade01]

The helmholtz on the Nameless front pipe is tuned to cancel out drone and some sound for their header. I have the cat less front pipe with the HH resonator and it sounds great, noticeable amount of extra grunt know too!

[ogrowup]

Does anyone have experience with a Ptuning 3" down pipe and catless header?
Mine really booms and drones between 3000-3500 RPM, especially when i lift my foot off the throttle.

Hoping a helmholtz resonator cures it-

[mid_life_crisis]

Originally Posted by sierra

You don't have to keep it so simplistic.
I'm sure we can manage to follow a more in depth explanation.

...and Satan said, "put the alphabet in math."

[Koa]

Originally Posted by wbradley

Here is a better explanation of a Helmholtz resonator:

It can be shown[2] that the resonant angular frequency is given by:

radian/s), where:

• <LI sizset="false" sizcache04063859185909552="43 116 21"> (gamma) is the Heat capacity ratio - Wikipedia, the free encyclopedia capacity ratio or ratio of specific heats. This value is usually 1.4 for air and Diatomic molecule - Wikipedia, the free encyclopedia molecule is the cross-sectional area of the neck
• is the mass in the neck
• P0 is the static pressure in the cavity
• V0 is the static volume of the cavity

For cylindrical or rectangular necks, we have




Anyone else here watch Big Bang Theory??

thanks for the copy/paste bahaha

[Ultramaroon]

rookie

[cdrazic93]

[Turdinator]

Originally Posted by reeves

I'm going to look into the Helmoltz too if I get a catless header & exhaust.. but those equations look like jibberish to me.. just tell me how many decibels does it drecrease the noise level at 3500 rpm WOT?

Also something else that I came across.. VaraFlow Muffler! It'd be great if you could adjust the sound of your own exhaust! But I don't know of anyone who's tried this product before..

You should have a look at this thread:
http://www.ft86club.com/forums/showt...ighlight=varex

[mid_life_crisis]

So the next question is, does anyone know where to find a simple chart to determine the correct size for our cars? Different charts for different diameters with rpm target on one axis and the length on the other? Or is it too complicated to reduce it down to something like that?

[cdrazic93]

Originally Posted by mid_life_crisis

So the next question is, does anyone know where to find a simple chart to determine the correct size for our cars? Different charts for different diameters with rpm target on one axis and the length on the other? Or is it too complicated to reduce it down to something like that?

This will answer that question along with alot more

http://www.gomog.com/allmorgan/exhaustbackpressure.html

[mid_life_crisis]

Originally Posted by cdrazic93

This will answer that question along with alot more

http://www.gomog.com/allmorgan/exhaustbackpressure.html

That was interesting and should probably be required reading prior to being allowed to post about exhausts, but it didn't address the question on Helmholtz resonator sizing.

[Boofneenee]

If it does it would be so trivial. However, from a curiosity standpoint I would guess it does

[BRZ.PTY]

Originally Posted by Ultramaroon

rookie

I did it with my ptuning 3inch exhaust. Droned like a b*** from 2600 till 3000. Its called a 1/4 resonator or branch resonator. Its not pretty but it works really good. Still drones a lil bit under relly heavy load but its like a 300% improvement over stock. its not annoyingly loud anymore at low rpm, doesnt drone and it does not affect the sound at higher rpms. If you guys want, I can post a detailed DIY on how to calculate the pipe length to cancel the desired frequency.

[cdrazic93]

Originally Posted by mid_life_crisis

That was interesting and should probably be required reading prior to being allowed to post about exhausts, but it didn't address the question on Helmholtz resonator sizing.

Ohhhh resonator sizing? Damn my bad, I thought it was about exhaust size.

[mid_life_crisis]

Originally Posted by BRZ.PTY

I did it with my ptuning 3inch exhaust. Droned like a b*** from 2600 till 3000. Its called a 1/4 resonator or branch resonator. Its not pretty but it works really good. Still drones a lil bit under relly heavy load but its like a 300% improvement over stock. its not annoyingly loud anymore at low rpm, doesnt drone and it does not affect the sound at higher rpms. If you guys want, I can post a detailed DIY on how to calculate the pipe length to cancel the desired frequency.

As long as it doesn't involve calculus, which has completely purged itself from my memory, that would be appreciated.
How much of a range is one effective for? For example, I'm most concerned about cruising through the neighborhood in the morning, which centers around 2000 rpm or so, but highway cruising at 2600 would be nice to have a little quieter too. If I tuned for 2300 would it be effective for all of that range?