Stock Helmholtz Resonator on a 318

[JedIEG]

I just though this was interesting and had never seen it on another motor. This is the 318 out of my 72 Satellite with a seemingly factory exhaust crossover with a Helmhotz resonator. As an engineer this is just interesting to me an thought I would share. I was wondering if anyone else has seen this on their cars or know what applications Chrysler used this on?

 

[super-bee_ski]

Clarification for anyone who does not know what it is:
From Wikipedia : Helmholtz resonance is the phenomenon of air resonance in a cavity, such as when one blows across the top of an empty bottle. The name comes from a device created in the 1850s by Hermann von Helmholtz, the "Helmholtz resonator", which he, the author of the classic study of acoustic science, used to identify the various frequencies or musical pitches present in music and other complex sounds

Why use this? : When air is forced into a cavity, the pressure inside increases. When the external force pushing the air into the cavity is removed, the higher-pressure air inside will flow out. The cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. This process repeats with the magnitude of the pressure changes decreasing each time.

Applications: Helmholtz resonance finds application in internal combustion engines (see airbox), subwoofers and acoustics. Intake systems described as 'Helmholtz Systems' have been used in the Chrysler V10 engine built for both the Dodge Viper and the Ram pickup truck, and several of the Buell tube-frame series of motorcycles.

Both explanations are from Wikipedia

 

[Photon440]

Someone may have capped that tube off, if it isn't still open. It looks like part of the plumbing that was used for the air injection into the exhaust manifolds for emission controls.

 

[72Fourspeed]

Ford used a similar setup on some of there engines in the air pump days. Should be a one way valve between tube and air pump.

 

[Herr_Poopschitz]

Yup, emission controls crap. Not sized as a Helmholtz resonator. Only app I've seen for a HR in exhaust is downstream by the mufflers (or in mufflers) to reduce drone.

 

[Meep-Meep]

Correct. Air injection manifold.

 

[YY1]

Isn't 72 a bit early for that?

My 86 5th Ave had it.

 

[Hemi Rebel]

Isn't 72 a bit early for that?

My 86 5th Ave had it.

Check the date on the block

 

[72Fourspeed]

Maybe later heads were swapped on to get the hardened seats ?

 

[Photon440]

Isn't 72 a bit early for that?

My 86 5th Ave had it.

When did Chrysler start using air pumps? I know Ford had it at least as early as 1968, and GM back in 1966, but don't know when our cars started. At any rate, it's not out of line for 1972, here's a TSB from that era:
http://www.hamtramck-historical.com/images/TSBs/1972/25-03-72C.jpg

 

[YY1]

My 73 does not have it.

Is it a California car?

One thing I liked about 70's Mopars (back in the 80's), is that they didn't have air pumps, like ford and gm.

 

[Herr_Poopschitz]

FYI...this is what a Helmholtz resonator would resemble (all the junk hanging off the tube). Purely an acoustic application to reduce the volumes of certain frequencies - in this case the sucking sound the intake manifold makes for NVH purposes.

 

[JedIEG]

Yep I am finding that I have been lied to about most of what this car is. The block is dated 83. Im starting to wonder if I am rebuilding a car that was pulled out of the junkyard

 

[Photon440]

Are you still thinking of using the 340, or looking for the magnum/a518 combo?

 

[JedIEG]

I'm thinking a 360/a518 would be a good cheap alternative to rebuilding the 340 (which will need a lot of machine work) I will probably start the rebuild on it eventually just because I know I will use it in another project or if the 360 in my dad's Cuda goes south.