Completely eliminated exhaust drone
- Thread starter LX Dave
- Start date
-
Sponsors (?)
For those that are new to the concept, there are tons of online calcs to figure out resonator length. Easiest way to figure out your drone freq is to download a spectrum analyzer on your phone and go do some driving - the freq will change a bit with temp of the exhaust. But a 1/4 wave will cover a pretty broad area.
Mufflers are too small to handle the full wavelength and each motor combo will be different. But this is the right way to address drone - every major auto manufacturer does this on the intake/exhaust side to get the sound(s) they want.
OP - did you measure the DB drop in that annoying freq range? I'd be curious how much it dropped w/ 2 1/2" pipe, since chamber volume will impact attenuation as well.
Mufflers are too small to handle the full wavelength and each motor combo will be different. But this is the right way to address drone - every major auto manufacturer does this on the intake/exhaust side to get the sound(s) they want.
OP - did you measure the DB drop in that annoying freq range? I'd be curious how much it dropped w/ 2 1/2" pipe, since chamber volume will impact attenuation as well.
This was a freshly completed build last summer, and although I did put a bunch of miles on it, it was mostly tuning the fuel injection. Haven't had it on a dyno yet, but would like to soon. It shouldn't effect horsepower at all since only sound waves travel back and forth through the resonator. Seat of the pants, it feels the same.
The sub frame connectors are ones I built. They work really well too. When I jack on one corner, that whole end comes up fairly straight, love it.
I never thought of checking decibels before and after. I do know it's a huge difference. Before, I couldn't stand it more than 20-30 minutes. Now, it gets really quiet inside the car when cruising at the effected rpms.
I used earplugs with the Dronemasters and off road x pipe the car came with when it was on the highway. I replaced them (the mufflers, not the earplugs) with super turbos. It sounded better at idle, and a lot quieter at full throttle. But the drone was still 2/3 (not measured) at cruising. The high perf BBK catted X pipe made my stereo useful at cruise again, but it’s still more than I want on the highway. The car still gets the neighbors’ attention and I get asked “is that a Boss in there?”. But the drone on the highway has to go.
Any idea how much weight this adds? Was clearance to the subframe connectors or ground an issue?
Any idea how much weight this adds? Was clearance to the subframe connectors or ground an issue?
I used 2.25" pipe for the resonators, so 2-24" sections, 2-elbows, couple clamps, end plugs, some weld, would guess only 10-15 pounds.
Ground clearance is good yet. When I did this, I kept the resonators at the same level of the H-pipe.
Before taking the H-pipe off, I measured from the H-pipe to the sub-frame connectors front and back. The 2x4 on the first picture is where the sub-frame connectors would be minus approx. 3-4 inches (I wanted to keep it as tight to the H-pipe as I could). The 2x4 also was a good reference to keep the resonator parallel with the car.
Ground clearance is good yet. When I did this, I kept the resonators at the same level of the H-pipe.
Before taking the H-pipe off, I measured from the H-pipe to the sub-frame connectors front and back. The 2x4 on the first picture is where the sub-frame connectors would be minus approx. 3-4 inches (I wanted to keep it as tight to the H-pipe as I could). The 2x4 also was a good reference to keep the resonator parallel with the car.
For those that are looking for some of the math and theory behind it, this has some pics drawn in crayon for the visual learners and a spreadsheet for those with more wrinkles on their brains.
https://www.9thgencivic.com/threads...-wave-resonator-engineering-explained.225275/
And then if you want read the 1 useful post in the long exhaust drone is gone thread, it's this one: https://forums.corral.net/threads/exhaust-drone-is-completely-gone.496793/page-5#post-9490650
https://www.9thgencivic.com/threads...-wave-resonator-engineering-explained.225275/
And then if you want read the 1 useful post in the long exhaust drone is gone thread, it's this one: https://forums.corral.net/threads/exhaust-drone-is-completely-gone.496793/page-5#post-9490650
Oh, and 1 more that is really good: https://www.performancetrucks.net/f...-resonator-tube-eliminate-drone-489463/page3/
marcelo
Active Member
Post #27 (6 posts up) he listed exactly what he used, and that his pipes were 24" long.
Cool thread I didn't catch when it was posted. I need to do this in my black turbo car. I went to super turbos knowing they weren't enough muffler to support its power levels. So, I also went with an electric cutout. Maybe this is the direction I need to go.
Very interesting read and got me going down a rabbit hole on the resonation calcs.
So for those of you that have converters on the their cars do you have drone or not? If so what mufflers are you using and if not what mufflers are you using? The x-pipe with the cats in it reduces everything in the exhaust in my Coupe compared to the x-pipe without them and this is running equal length shorties, BBK x-pipe (both catted and not), and a Flow Master cat back with two chamber mufflers. I have never expected my car to be quiet and what little drone it has on the highway doesn't bother me. I will say that my car had dynamat on the floor pan, doors, and the roof so that probably kills most of it anyhow.
So for those of you that have converters on the their cars do you have drone or not? If so what mufflers are you using and if not what mufflers are you using? The x-pipe with the cats in it reduces everything in the exhaust in my Coupe compared to the x-pipe without them and this is running equal length shorties, BBK x-pipe (both catted and not), and a Flow Master cat back with two chamber mufflers. I have never expected my car to be quiet and what little drone it has on the highway doesn't bother me. I will say that my car had dynamat on the floor pan, doors, and the roof so that probably kills most of it anyhow.
Drone on all 3 cars, no converters on any of them. All 3 drone, though the kilmat in Grover and Black Jack significantly help. Black Jack has flowmaster 40 series 2 chambers. I'll have to go look up what's on Grover. The Black turbo car had Dynomax Ultraflos & now super turbos in an attempt to kill the drone. Still drones like hell, but no sound deadening.
So your turbo car drones? I would have thought that with the impeller breaking up the exhaust wave that it would be quiet. Guessing inside the car is totally different than hearing them outside though.
Similar threads
