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I hope you get the drone taken care of Ron , I don't think anyone here is challenging your experience working on cars . I really think most guys just hear things differently.
Each of us have a different ear for what sounds like a good exhaust , then age comes into play haha.
I hope you get things straightened away soon with your exhaust.
I can't say I have read a thread such as this , however ... I'm sure this will come to mind prior to the next exhaust install for some.
Also , I'm sure this will help any new guys coming into the hobby, wondering how to dial in an exhaust system for Zero Drone !
Interesting thread without a doubt, I'm still following along, looking forward to the final outcome .
All the best!
Eric
Thanks for the well wishes Eric. Damn Canadians are so nice! I always appreciate learning things when someone shares their experiences on forums. I hope I can return the favour and help someone out who is dealing with this same issue. Lsx442 - I am very happy with the new install. I like when the installer takes the time to spray all the welds. Even the ones that aren't his!
Hey guys, for what it's worth, I remember stock style turbo mufflers not having any drone whatsoever. I have some on my 442 now & it does sound decent at idle, but pretty boring otherwise. Now, on my Skylark, I have a decent system with DynoMax tubo style mufflers, (not sure what model) manifold 2 1/4" pipes and a bad DRONE at 50 mph. Above & below that speed, it isn't bad & sounds like a muscle car should IMHO. I'm going to try the sound deadener & see if it help. I think it's hard to have the best of both worlds, bad *** sound, and no drone.?? I'm going to put new mufflers on the 442 because it's too quiet......now enter drone problem. haha
I have the exact same issue. I moved the shorty headers 2.5" duals with X pipe from my 88 Cutlass, too much for a 260. It sounded amazing and nearly no drone on that car, just slightly loud. On my 70, drone like yours plus vibrations. So I added expensive custom full length tail pipes, barely quited it down at all. The Hooker Aerochamber mufflers are loud. Summit Turbo mufflers I think they are even quieter than the Dynomax Superturbo mufflers, look at the reviews for this XL muffler, they complain it is too quiet. I am putting that exhaust back on 88 and going Thornton shorties and 2.5" down pipes from Rocket Racing and probably Summit Turbo mufflers. I think Joe is on to something with the hangers being too stiff. Mine is contacting near the cross member hump, being bent for a G body and probably resonating through the body and creating the drone.
Thanks for the well wishes Eric. Damn Canadians are so nice! I always appreciate learning things when someone shares their experiences on forums. I hope I can return the favour and help someone out who is dealing with this same issue. Lsx442 - I am very happy with the new install. I like when the installer takes the time to spray all the welds. Even the ones that aren't his!
I enjoy learning myself. I came here with a basket case of questions for my 76 SBO back in 2013. So many guys have helped me out here with some great suggestions.
Some of Us Canadians are nice for sure, however so many guys from around the world here are just a nice and helpful.
Now... Your Exhaust !
I also think the new system looks great! Nice install with a touch of customer appreciation for spraying the welds.
I'm sure the shop will satisfy your needs from looking at the quality install.
Your in Bradford , nice country up that way , I'm about 45min west of you. Good to see they still have good exhaust shops out that way.
Eric
Last edited by 76olds; October 2nd, 2018 at 04:09 PM.
...Again, the mufflers are likely the problem. Keep the pipes, get Walker Dynomax Turbos (if you want a musclecar sound) or Walker QuietFlow (if you want stealth).
agreed - welded chambered mufflers are loud
Originally Posted by Olds64
x2
Changing the mufflers will have more of an effect on the sound than the diameter of the pipe. 2.25" vs 2.5" is insignificant.
not true at all - went from fabbed 2-1/4" to PYPES 2-1/2" with same type muffler - MUCH louder, though no drone
not true at all - went from fabbed 2-1/4" to PYPES 2-1/2" with same type muffler - MUCH louder, though no drone
I still believe 2.25" vs 2.5" won't make much difference. It's a bummer the OP spent so much money on his exhaust and still isn't happy. I had 2.5" dual exhaust with an X pipe installed in my 71 98 years ago and I've been happy with it from day one. It's house bent aluminized pipe with 45" glasspacks. The Thrush glasspacks have started to mellow out even more since they're 7+ years old.
Just wanted to update on my drone situation. After discussing the issue with the installer, he asked that I try one more thing. He was not as confident as I was about the 1/4 wave resonators. He felt it was hacking up his nice install. He made up these weights of pipe filled with sand that are clamped on. He suggested that they may help with some vibration. I tried them in a few places along the system. Sadly, no change no matter where I put them. Still determined, but I had to find a shop closer to home. I tried my local family owned shop where I got the car certified. I was surprised to find out that the Owner was an exhaust guy. Between the time waiting for my appointment, I received my set of Thornton SBO shorty headers. I read about headers helping with drone issues. I was hoping they might change the speed of exhaust just enough to make a difference. He was very aware of what I wanted, as he'd just installed one for another customer. I wanted to install both the headers and 1/4 wave resonators at the same time, but the header install took much longer than expected. Ended up having to replace motor mounts, so we couldn't do the 1/4 wave pipes. I am really happy how the headers turned out, but sadly, they did nothing to help the drone. I was not really surprised, as these aren't really headers. I consider them to be pretty manifolds. Can't really tell if they helped performance any, which is ok with me. But I am doing a carb swap as well, and figured these wouldn't hurt. I am going to make a separate thread with pics for those interested. I will update again when I get the J pipes installed to let you guys know if it was successful in getting rid of the drone. Pics below..
After reading all this, I have 2 suggestions. Install the factory style exhaust hangers. GM spent a ton of money figuring out the best compromise of exhaust sound, performance, and comfort. You can be sure they didn’t design anything that might cause issue once the car was on the road. If only one care in 500 suffered from exhaust noise, that’s still a huge number or complaints!
Second idea, head to your nearest car stereo installation place and get a few of the glue on sound deadening pads. Stick them to the floor on the drivers/pass side, under the rear seat, etc. maybe that will help keep the floor from vibrating. You could also glue them to the inside of the doors, the quarter panels, anyplace that is a large unsupposrted section of sheet metal. I’m guessing it wouldn’t take much to make things resonate like a drum.
I think the H pipe could help. Anything to smooth out the exhaust pulses has to be a plus. Have you tried retorquing the engine mount and trans mount bolts? Maybe loosening them, shift the engine ever so slightly on the mounts, and tightening them up again? What condition are the body mounts in?
After reading all this, I have 2 suggestions. Install the factory style exhaust hangers.
As recommended waaaay back in Post #34.
Also, the OP claims to have tried Walker Super Turbos, but I don't see them anywhere in the photos in this thread. I see Thrush. I see Maganflow. I see what appear to be Flowmasters. Nowhere do I see any photos with these, which were recommended way back in the beginning.
Thanks for the input Matt and Joe. I have an H pipe in the system currently. I have the Walker super turbos sitting on my shelf. No difference.
I promise, if it the hangers that is causing this, then I will definitely find out. I won't rule out anything. I believe there is more to it. I am going to double check the tranny mount as well. When under the hood reving the motor, I can create the drone very easily. That's drone with no load from the drive line. I swear it's as if the drone starts right at the manifolds and goes down. I am still confident that the 1/4 wave resonators will help. Hangers aren't that pricey, and will probably order them anyway.
"Confuscious says.... Its always easier to ask for advice than it is to follow the advice." Confuscious also say.... maybe you should read a Science book...
Hey Folks,
Just wanted to do a final update to this post. I know there are lots of people out there that have this issue, so I hope my experience can help them out. I am extremely pleased to say I have finally eliminated all of my annoying drone!!! As I suspected all along, my drone had nothing to do with vibration, muffler type, or what mounts/clamps were installed. Without getting too technical, as that would take way too long, the main cause of drone is the resonant frequency of engine and exhaust combined. This is where the science comes in. There is LOTS of information available on the net if you want to learn more about it. I designed an adjustable 1/4 wave resonator Jpipe, and had it installed as close to the engine as possible. The adjustable part is so that you can tune out the offending frequency by changing the length. Once I am 100% sure I found the magic spot, I will have it chopped, welded and primed. It works perfectly. I wanted it tucked up as high as possible so it wasn't visible from the side or rear. This installer did a great job, and he never once questioned what I wanted. The other installers I asked to do this job thought I was crazy. Some guys think they know everything I guess. If anyone wants to know how I came up with the numbers, ask away. I have posted pics below. I couldn't care less about opinions on how it looks. I love what they do, and can finally enjoy driving without that head splitting drone!!! By the way, it DID NOT change the tone of the exhaust. Cheers to all...
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
That's an interesting approach, but I'm thinking it will play hell with your flow pattern after the cross tube. Glad you're happy with it but honestly it's nothing I would try.
your problem is your engine can blow though 1 straw, add a second one, make 2 bigger = drone as your engine doesnt produce enough....ummph.
I dont mean to sound like a dick, but the picks/ install/ your **** you added, I've never seen anything like that before. Again glad it worked out.
the pics you have all I see is the cheapest mufflers......like said 22 dynomax that's what I and alot of others have.
good luck and Patton your exhaust design
Last edited by truckman5000; December 4th, 2018 at 05:12 PM.
That's an interesting approach, but I'm thinking it will play hell with your flow pattern after the cross tube. Glad you're happy with it but honestly it's nothing I would try.
Can you please explain the potential flow pattern problem? Since no exhaust gases pass through these pipes, I don't see how it will hurt. The pipes remain cold to the touch. The sound waves is what I was after, not the exhaust flow. Are you saying that there would be turbulence? I haven't noticed any performance loss. Then again, I don't expect any performance out of this little stock 2 barrel anyways. I have other cars for that.
your problem is your engine can blow though 1 straw, add a second one, make 2 bigger = drone as your engine doesnt produce enough....ummph.
I dont mean to sound like a dick, but the picks/ install/ your **** you added, I've never seen anything like that before. Again glad it worked out.
the pics you have all I see is the cheapest mufflers......like said 22 dynomax that's what I and alot of others have.
good luck and Patton your exhaust design
You mean the 3 different types of mufflers I installed were the problem? You've never seen this before because you didn't look for it. This is a very common solution to this problem. GM uses this in many new performance muffler systems...
I am glad it worked, I am hoping I will not have to get that drastic. I am probably going full length headers, 2.5" X pipe exhaust with straight through mufflers. I am planning on something better than even my 350 4bbl, so 260 manifold's, 1 7/8" dual exhaust with angled glass packs won't do, I had no done even without tail pipes.
I am glad it worked, I am hoping I will not have to get that drastic. I am probably going full length headers, 2.5" X pipe exhaust with straight through mufflers. I am planning on something better than even my 350 4bbl, so 260 manifold's, 1 7/8" dual exhaust with angled glass packs won't do, I had no done even without tail pipes.
I think you should normally be ok with a regular set up. My case seems to be vehicle specific. This is the only car that has had this issue. I believe it has more to do with my weak almost stock motor tranny combo. It even droned with single exhaust and one (drone) flowmaster muffler. I was ready to drop in a 455/th400 if this last step didn't do the trick.
Interesting. I've never seen this before either. It's good that you're happy though. These are available aftermarket and may have accomplished the same thing.
Interesting. I've never seen this before either. It's good that you're happy though. These are available aftermarket and may have accomplished the same thing.
They look similar, but thats where it ends. And the price!? It appears that those units are tunable mufflers. The pipes I have do not allow any exhaust to flow through them since they are capped. As I stated before, these remain cool to the touch no matter how hot the exhaust gets. The only heat these pipes get comes from transferance by being close to the main pipe. These pipes allow sound waves to bounce back and knock out the offending frequency. The frequency I wanted to remove was between 120 thru 145 Hz. That is the common frequency for drone in most V8 engines. I measured the Hz during my drive to pinpoint where the worst drone occured. These 1/4 wave resonators are used in many other applications, including ventilation systems and generator exhaust systems. If you cut open the suitcase style mufflers on the new Camaros, you will see the same type j pipes as mine, albeit on a smaller scale... By the way, I paid less than $100 for him to bend them up and install.
Last edited by Ron68; December 6th, 2018 at 01:32 PM.
They don't even look similar. The Super Trapps are mufflers, not a hemholz resonator.
Which part didn't you understand Joe? To an untrained eye, they may look similar. Sorry if you didn't like my explanation. I know those were mufflers, but maybe he didn't. It sucks when you're not right about everything... I guess you feel bad all of your advice didn't help in this situation. You made plenty of smart a$$ remarks through this whole thread. I did all this to try to help others to not have to go through what I did. I wasted time and money, and would have loved to find this solution before I redid the exhaust the first time. This post was for people who wanted to learn something, not for the know it alls who are Masters of the Cutlass Universe like yourself. I guess you won't help me anymore, oh well, I'm perfectly fine with that. I'm sure you've been called out on this forum for your know it all attitude before.
Which part didn't you understand Joe? To an untrained eye, they may look similar. Sorry if you didn't like my explanation. I know those were mufflers, but maybe he didn't. It sucks when you're not right about everything... I guess you feel bad all of your advice didn't help in this situation. You made plenty of smart a$$ remarks through this whole thread. I did all this to try to help others to not have to go through what I did. I wasted time and money, and would have loved to find this solution before I redid the exhaust the first time. This post was for people who wanted to learn something, not for the know it alls who are Masters of the Cutlass Universe like yourself. I guess you won't help me anymore, oh well, I'm perfectly fine with that. I'm sure you've been called out on this forum for your know it all attitude before.
Off the meds? Geeze, that wasn't even a criticism of your particular post... I was AGREEING with your point.
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
Originally Posted by Ron68
Can you please explain the potential flow pattern problem? Since no exhaust gases pass through these pipes, I don't see how it will hurt. The pipes remain cold to the touch. The sound waves is what I was after, not the exhaust flow. Are you saying that there would be turbulence? I haven't noticed any performance loss. Then again, I don't expect any performance out of this little stock 2 barrel anyways. I have other cars for that.
I can't understand how you wouldn't get turbulence that affects the flow of exhaust where the chambers come off the side. Hot exhaust is going to take both routes, until there is resistance which will force it back to the entrance thus creating the turbulence I was referring to. If it's nothing you're worried about, neither am I. Just nothing I would do with my car, that's all. I do have some drone from my Walkers so I'll be replacing them with 21" Dynomax super turbos. It'll be next year before I can report back to you on them but I expect they will work perfectly for a factory quiet dual exhaust sound. I have thought about the Race Bullet series for the throaty exhaust sound. On the fence with that.
Off the meds? Geeze, that wasn't even a criticism of your particular post... I was AGREEING with your point.
Ok Joe, I will give you that one. I was off my meds. But I am fully medicated now. In your reply, you quoted my post, not his. I had assumed you were correcting me for my explanation.
Perhaps my reply sounded a bit strong, but I just want to explain what I did to solve my drone problem. This may help others in the same boat. They are easy to make, and when done correctly, will solve the drone problem every time. I will use this same setup on any of my cars that need it. I learned this info from another forum, just thought I would spread it here for others who wanted to see it in action.
The frequency I wanted to remove was between 120 thru 145 Hz. That is the common frequency for drone in most V8 engines. I measured the Hz during my drive to pinpoint where the worst drone occured.
How did you measure the droning frequency? To eliminate the offending frequency did you just move the J pipes until it "sounded right," or is there a science to it?
I've never used the Super Trapp mufflers I posted earlier, I always @$$umed they were geared more towards racers or the tuner import market. To tune Super Trapps I guess a user would add or remove discs for max HP on a dyno or a desired sound.
How did you measure the droning frequency? To eliminate the offending frequency did you just move the J pipes until it "sounded right," or is there a science to it?
I've never used the Super Trapp mufflers I posted earlier, I always @$$umed they were geared more towards racers or the tuner import market. To tune Super Trapps I guess a user would add or remove discs for max HP on a dyno or a desired sound.
Although I have real measuring devices on my electronics work bench (I repair audio equipment, one of my other hobbies), you can just get an App for your phone to measure the frequency. I used one called Spectroid. Just start the App and put your phone in a cup holder or passenger seat, and it will measure the decible level and frequency on an easy to read graph. You need no special skills to operate. It can display the peaks in real time as you are driving, so you can easily determine the correct frequency. You can then cut the 1/4 pipe to the required length. Download the free app and try it. You can test it with your own voice or any other sound to see it work. If you want the formula to calculate the length, I can look it up and post here.
Forgot to answer your other question. Yes, you slide the pipe in or out to tune out the drone. It can only remove a very narrow bandwidth of frequency, so you want to start out very close to the calculated length. Many people don't use an adjustable one. They cut to length and hope for the best. I wanted more control just to make sure I hit it. For me so far, it ended up working within an inch of my original calculations, which was 24 1/2 inches. But I can adjust from 23 /1/2 thru 28 inches with the one I made.
Thanks for the info Ron. I might have to use that app in my Olds. My exhaust has a TON of drone, but it goes with the glasspacks.
In your case, the type of glasspacks may be the issue. I know people love them, but drone is a very common side effect when you use them. I'm not sure if the 1/4 wave j pipe can overcome the drone from that design.
Here is how I calculated my length.
Speed of sound divided by the frequency, then divide the number by 4 (1/4wave). Then take that number and times it by 12 to get the measurement in inches.
Example: My trouble frequency was 132Hz.
1092fps (approx. speed of sound) /132Hz = 8.27
8.27 / 4 (1/4 wave) = 2.06
2.06 x 12inches = 24.81 inches. That is your starting measurment.
Last edited by Ron68; December 7th, 2018 at 06:38 AM.
October 1st, 2018, 05:47 PM
I always appreciate learning things when someone shares their experiences on forums. I hope I can return the favour and help someone out who is dealing with this same issue.
Update
Can't really tell if they helped performance any, which is ok with me. But I am doing a carb swap as well, and figured these wouldn't hurt. I am going to make a separate thread with pics for those interested. I will update again when I get the J pipes installed to let you guys know if it was successful in getting rid of the drone. Pics below..
As I suspected all along, my drone had nothing to do with vibration, muffler type, or what mounts/clamps were installed. Without getting too technical, as that would take way too long, the main cause of drone is the resonant frequency of engine and exhaust combined. This is where the science comes in. There is LOTS of information available on the net if you want to learn more about it. I designed an adjustable 1/4 wave resonator Jpipe, and had it installed as close to the engine as possible. The adjustable part is so that you can tune out the offending frequency by changing the length. Once I am 100% sure I found the magic spot, I will have it chopped, welded and primed. It works perfectly.
If anyone wants to know how I came up with the numbers, ask away. I have posted pics below. I couldn't care less about opinions on how it looks. I love what they do, and can finally enjoy driving without that head splitting drone!!!
By the way, it DID NOT change the tone of the exhaust. Cheers to all...
I guess you feel bad all of your advice didn't help in this situation. You made plenty of smart a$$ remarks through this whole thread. I did all this to try to help others to not have to go through what I did. I wasted time and money, and would have loved to find this solution before I redid the exhaust the first time. This post was for people who wanted to learn something, not for the know it alls who are Masters of the Cutlass Universe like yourself. I guess you won't help me anymore, oh well, I'm perfectly fine with that. I'm sure you've been called out on this forum for your know it all attitude before.
