Does anyone know why they chose to put resonators on the Hemis?

[XH29N0G]

Just curious.  Can someone tell me why the original design put resonators on the 426 but not on the 440 cars? 

[aussiemuscle]

i don't know, but i'd say the highway drone?

[Ghoste]

I don't know for sure either but I think drone could be a very good guess.  I wonder if anyone with a stock Hemi Charger on here might have tried their car with and without the resonators?

[XH29N0G]

Thanks.  This makes sense.  It just seemed a little strange to me to put on one and not on the other, but choices made because of differences in noise levels/drone sound reasonable.

[HPP]

Price point? Imperials had resonators with their 440s, as did many Chryslers, but those buyers tended to be better financed than typically Chargers buyers. However, since Dodge was a step above Plymouth, maybe this is an added value feature.

[Ghoste]

Hemi Plymouths had them too.  Maybe it was just a noise cancellation thing?  Could be the Hemi was louder?  The Imperial buyer would certainly be expecting a silent 440?

[Dino]

Dodge was a step above Plymouth

Wait a minute!  you mean Dodge is of higher quality than Plymouth?  Holy crap!   

Come to think of it...I don't think I've ever seen a Plymouth up close.

[hemigeno]

I don't know for sure either but I think drone could be a very good guess.  I wonder if anyone with a stock Hemi Charger on here might have tried their car with and without the resonators?

I drove my '69 R/T with mufflers and no resonators for many years.  A friend who rode along on one road trip did comment that he couldn't stand the drone and would have to put some "quieter" mufflers on the car if it were his.  It didn't bother me at all - but then again, motor music is better than the radio to me.

After having installed resonators a few years ago, I didn't drive the car much more than a few hundred miles and didn't take any trips with the same friend.  It was quieter at highway speeds though (in my opinion).  Also just my opinion, but I would think resonators would be a lot more important for cars with 4.10 gears - even 440 cars.

[AKcharger]

What does a resonator do exactly, I thought it made the car sound louder??

[Ghoste]

I thought it was just an additional "mini muffler"?

[hemigeno]

Weirdly enough, on E-Bodies, the nomenclature is reversed if I'm not mistaken... the straight-through long tubes (shaped like Thrush mufflers) are called "mufflers", and the rectangular cans are called "resonators".  To me, a resonator is just a second muffler - as Ghoste mentioned.  It's shape may vary, but the purpose is the same.

While I'm no expert, the sound of a stock Hemi exhaust system is mellower and maybe a bit deeper than a 440's sound.  Whether that's a function of the cylinder head / exhaust manifold's design or the addition of the resonators, I couldn't say for certain.  Probably a little bit of both factors.  A lot also depends on the mufflers used.  Reproduction original-style mufflers like the ones YearOne sells do not sound quite like OEM mufflers IMHO, as the repops sound a bit tinnier to my untrained ear.

[XH29N0G]

So do you think it was mostly to compensate for noise of the factory Hemis because of a larger cam and valves compared to the factory 440s?

[Ghoste]

That would be my guess but its only a guess.  The Hemi would have higher port velocity would it not?  That would give the exhaust some bark and they do have a better flowing exhaust manifold.

[Tilar]

Back in 69 Dad bought a new Newport Custom that had a 383 in it, It had a resonator.

[TUFCAT]

It must've been done to address NVH (noise/vibration/harshness) issues at higher RPM. There's no good reason Chrysler to add the (restrictive) resonator to any performance vehicle exhaust system unless it needed to be there.  

Most of us know how bad exhaust can set up harmonic vibrations inside the car. Back then, this could've been the easy fix "to deal with it" - rather than Chrysler spending money to design and tool new exhaust systems for hemi's and 440-six packs...

[Mytur Binsdirti]

I have no idea why the Hemis got them, but here's what they look like. The factory resonators were welded to the tailpipes & are date coded. Service resonators were sold seperately from the tailpipes. Interestingly, '66 & '67 Hemi cars did not have them. Right now I'm on the fence as to whether I should clean these up & use them of just put on regular tailpipes. One thing's for sure; these suckers are rare.

[XH29N0G]

Cool, and thanks for sharing the picture of them.  I have learned a lot from this thread so far.  The high points for me are the pix and the new acronym (NVH).

[hemigeno]

One thing's for sure; these suckers are rare.

[HPP]

Back in 69 Dad bought a new Newport Custom that had a 383 in it, It had a resonator.

Chrysler...typically more demanding buyers who didn't want the NVH.

It must've been done to address NVH (noise/vibration/harshness) issues at higher RPM. There's no good reason Chrysler to add the (restrictive) resonator to any performance vehicle exhaust system unless it needed to be there.

Which comes back to addressing NVH and cost. Hemis were expensive even back then. Hemi buyers tended to have the bucks for performance but not all of them were wanting all the NVH that came with it.  Recall why the Road Runner and Super Bee were so popular? They were cheaper than most other big blocks. To step up to a Hemi required a big investement. Along with that investment came a bit more...refinement maybe?

[Mytur Binsdirti]

One thing's for sure; these suckers are rare.

Apparently, I was mistaken.   

[hemigeno]

Apparently, I was mistaken.   

Well, it only took me about 10 years to find a nice set with the dates I wanted, so I suppose it's all in how you look at it...

[Mytur Binsdirti]

My car was built in June, but the resonators are dated 3/68 & I'm sure they're the originals. 

[Ghoste]

I wouldn't be surprised about any Hemi part date coded a couple of months ahead.

[hemigeno]

I was looking for anything dated late '68, since the car was built circa 1/27/69.

I wouldn't be surprised about any Hemi part date coded a couple of months ahead.

Very true.

[Ghoste]

For that matter, is it not fairly common for the blocks themselves to often be cast many months before a Hemi Car build date?