Unbearable NA RoadsterSport 3 Drone.

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Unbearable NA RoadsterSport 3 Drone.

Postby BenB242 » Tue May 30, 2017 5:11 pm

I recently installed a RoadsterSport 3 exhaust to my 1995. It has a horrible drone from 2,750-3,250rpm once the exhaust gets warm. It's bleeding ears bad. The baffles help very, very slightly, but even the packed baffle still drones. I did a lot of research on this exhaust and a common praise people had was its lack of drone so I don't know what's going on with mine.

It has about 750 miles on it so far, so I think it's broken in enough. I replaced the gasket that came with the exhaust at about 600 miles because it had failed or never sealed properly to begin with. There was a huge carbon streak across the gasket. I thought for sure that's what was causing the drone. I replaced the bad gasket with a Walker OEM style and also used some Permatex copper RTV for good measure. The flanges were held flush before putting the bolts on and the bolts were tightened to 40ft/lbs. I was disappointed to find that the drone hadn't even been slightly reduced with the new gasket. I'm fairly sure that I installed everything correctly and that's not where the issue is coming from, but I'm open to ideas.

After searching this forum I found someone with a similar issue and they were told to stuff the trunk with blankets to see if that would help. I tried that and if anything it made it slightly worse.

I really love the sound of this exhaust everywhere but 2,750-3,250. And considering I spend most of my time in that range, I can't bear it for much longer without fixing the drone. I'm seriously considering selling or returning this exhaust and going back to OEM if it can't be fixed and I really don't want to. It's unbearable. I'm open to any suggestions.
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Re: Unbearable NA RoadsterSport 3 Drone.

Postby Brian » Tue May 30, 2017 8:58 pm

Indeed the gasket had nothing to do with it, a little carbon will leak out with moisture leaking out and that does not equate to sound leaking when the system is hot. Since you have sealed it all up and it made no difference, you already know this now.

Break in period at least a 1000 miles, it's a process of all the highly reflective metal surfaces getting coated with carbon. If you take a lot of short trips it can be less than 1000 miles, but if your daily drive is long, then the motor is running efficiently most of the time and not making a lot of carbon and break-in time can end up being a few thousand miles. A number of other variables impact the process including fuel quality, state of tune on your Miata, etc.

Other than wait for further carbon coating of inside of the system, which will change the natural resonance in the system, the only other choice is adding a quarter wave pipe or helmholtz resonator (see Synapse NoDrone for example).
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
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