Resonator and glass pack questions

[70 Cam Guy]

Hey all, I have tried searching but I decided to ask everyone's experience.

The background: my 73 240 with round tops and ZX dizzy. I installed a used exhaust fitted with a 40 series flowmaster. With the stock exhaust manifold, it sounded great, not too loud.

Recently I installed my Clifford header and cleaned up the engine bay a bit. The new situation is the exhaust is considerably louder and now I get a persistent drone on the freeway. (it also revs significantly faster )

I have read many many threads with people adding a resonator in the middle to cut the drone. What I can't decide on is the style of resonator or glass pack to install in the middle section. I am looking at 2 styles of glass pack: perforated internal tube & traditional glass pack style with internal louvers

traditional glass pack

http://www.summitracing.com/parts/BIG-50252FLT/

perforated tube style bullet muffler

http://www.summitracing.com/parts/WLK-24215/

Those of you that have a resonator, which style are you using? I know the perforated internal tube is ideal for flow, but can anyone say if it cut a significant amount of the noise/drone? Did the benefit of the resonator fade as it broke in (ie burned out the fiberglass)? Perhaps it wasn't enough of a difference to be a bother? Did adding a resonator cure the drone to your liking?

I'm just looking for impressions/experience, I know exhaust noise is VERY subjective, thanks!

[70 Cam Guy]

To follow up, does the 4" outside diameter muffler fit under the car? If the 4" dia bullet muffler doesn't fit or sacrifices too much ground clearance, that makes the decision pretty easy..

[70 240z]

If you don't mind can you post some type of mp3 or wav of the sound of your exhaust as it is now, and also once you decide how to change it. I'm restoring a 71 240 and trying to figure out what to do with the exhaust. Thanks.

[70 Cam Guy]

If you don't mind can you post some type of mp3 or wav of the sound of your exhaust as it is now, and also once you decide how to change it. I'm restoring a 71 240 and trying to figure out what to do with the exhaust. Thanks.

I'll do my best but it's going to take some time. I've got a header leak to fix before I can really give you a representative recording. I have to sort out the exhaust before Oct 2 because that's when I'm driving to JSSC with my friends... 400 miles in the Datsun to Irvine!

As is, I really like the sound at idle, pretty mean. If you don't like flowmasters on muscle cars, I'm not sure it will change your mind.

I'll be pretty happy if I can just turn the volume down for driving.

[ChrisZ]

If you are going to add a resonator, i would advise you to put it in the back and have the glass pack in the middle.

I have experimented with different lenght of pipe after the rear glass packs and the change in sound is huge, try and watch my you tube video, there i have a piece of 6 inch pipe and the sound is crisp, if i take them out it will become more hollow.

Chris

[Arne]

What size pipe are you running? That will also make a difference in sound.

As for fit, I have a 24" glass pack running below and next to the driveshaft in my car, no issues at all.

[70 Cam Guy]

What size pipe are you running? That will also make a difference in sound.

As for fit, I have a 24" glass pack running below and next to the driveshaft in my car, no issues at all.

Thanks guys, much appreciated.

The exhaust after the connection to the header is 2.5". I figured that is where everyone installs a glass pack... seems like a perfect spot. Plus, being a nice straight section, it should be easy enough to weld in a glass pack

Chris, I remember watching your youtube video on your dual exhaust build and I really like the design. It also sounds great!

[70 Cam Guy]

If you don't mind can you post some type of mp3 or wav of the sound of your exhaust as it is now, and also once you decide how to change it. I'm restoring a 71 240 and trying to figure out what to do with the exhaust. Thanks.

I fixed my header leak, I'll do my best to get before and after recordings. I bought a Summit glass pack with a 12" body, 18" overall length.

It's nothing fancy, we'll see how it goes

http://www.summitracing.com/parts/SUM-630805/

[70 Cam Guy]

If you don't mind can you post some type of mp3 or wav of the sound of your exhaust as it is now, and also once you decide how to change it. I'm restoring a 71 240 and trying to figure out what to do with the exhaust. Thanks.

Here's what I have so far... sorry, not sure if the audio is quiet or not... through my stereo with subwoofer, this sounds pretty accurate

I'm officially another guy on the internet that starts his car and revs the engine for the camera :stupid:

http://smg.photobucket.com/albums/v283/70CamGuy/240Z/?action=view&current=MVI_0287.flv

Getting on the freeway, camera work is not ideal but we're here for the sound...

http://smg.photobucket.com/albums/v283/70CamGuy/240Z/?action=view&current=MVI_0288.flv

Cruising at 70-75 on the freeway and still getting passed. Some might notice the tach is working here. The drone doesn't seem that bad on camera but I couldn't hear the radio and could barely hear my bluetooth

http://smg.photobucket.com/albums/v283/70CamGuy/240Z/?action=view&current=MVI_0289.flv

Fast forward 24 hours and I've added Summit's 12" glass pack, painted the flowmaster flat black, and cleaned the chrome tip (also an oil change and electric fuel pump). The result is much quieter, almost a more refined sound. I am VERY happy with the result. It still sounds good and I can hear my stock 1 speaker radio again. I was hoping the mic would be sensitive to the volume difference but it's more subtle in the video

http://smg.photobucket.com/albums/v283/70CamGuy/240Z/?action=view&current=MVI_0290.flv

It's been a long weekend so I haven't had time to do an "after" driving video. Hope you guys like it

[doradox]

It sounds like you are happy with the results. FYI if you want to fine tune the sound the length, diameter, shape of the exhaust tip can make big differences in the sound. On my first '73 I put a turbo muffler and 2.5 inch pipe on it and had a short 2.5 inch diameter tip. Resonated like crazy and was way too loud inside. Added 2 inches to the tip and all that went away.

Steve

[70 Cam Guy]

Thanks, Steve. I've thought about changing the entire muffler and tip when funds allow. Currently the tip ends at the edge of my bumper. From what I've heard from my friends the flowmasters generally drone on 4 and 6 cylinder inlines. I guess I was just thinking longer tip meant less fumes in the car. Strangely enough, a muffler in the absolute rear of the exhaust is still new to me.

[ezzzzzzz]

On my 240Z I run a Janspeed s/s header. The collector tubes (2" each) slide onto the end of the header. These come together midway down the transmission. The single collector tube then centers under the driveshaft. The exhaust opens up to 2.5" and immediately enters a 12" Magnaflow resonator (I hate glasspacks). The mandrel bent tubing continues out back to a Magnaflow straight-thru 14" muffler. It was so quiet that I actually placed a 7" sleeve inside the resonator trying to increase the exhaust tone. Only when I stand on the gas pedal does it really come alive. Sounds very much like a traditional european sports car.