Just to reiterate: the drone I’ve got doesn’t vibrate the car in a way I can feel, it’s playing a note at 129-134hz that I can hear. I used a spectrum analysis app. Also, I can set the EFI to idle at 1800+ so I can get out and walk around the car and listen. No drone to be heard on either side outside the car. Only hearing that continuous note standing behind the car, or sitting in it. I have another app on my phone that can play a tone at any frequency. I connected it to my stereo that has a couple of subs. I play the tone at 129hz or so and it clashes with the sound the car is making and turns the whole noise into a trippy wawa guitar effects pedal. I was hoping it’d cancel it. I even wired the subs out of phase. Lol. Nope. I think my cars exhaust is acting like a pipe organ. Maybe the sound is coming inside because of the shape of the bumper. The tips stick out a little right under the bumper, facing the ground, but the shape of the bumper means that edge is further forward than the area that meets the trunk. Maybe the tips are too far in and pointing them at the ground is bad. I’ll try some extensions/resonator tips, maybe extend them to point straight back or to the side.
I probably should have put them in the tailpipes. Having them closer to the front to dampen sound earlier in the system seemed logical to me. If it’s the pipes acting like a musical instrument - a tuba? - then there’s still too much of it after the mufflers. I’m gonna try some tips that have resonators in them and if that doesn’t do it, either add more resonators in the tailpipes by the outlet or take the ones I added to the front and put them there. During my lunch break I’m going to drive the car a bit and see what’s what.
Ultimately, youre going to fight drone or resonance in any 2.5 or 3.0 inch system (unless youre extremely lucky) As much as I like the Dynomax mufflers I recently switched to stamped case Vibrants and while I dont love the tone, they do drone less (and I picked up a couple 10ths too.)
hmmm… fast and drone or slower and quieter… hmm I drove it around for an extended lunch. 0-40mph, mellow… 40-55 mph, around 1800…. Drone city. 62 and up… just hear wind and road noise. From a standstill, foot to the floor… Quiet idle Tire squeal Engine noise Exhaust growl Siren “Sorry officer, I was testing my exhaust. How did it sound to you?” that last part didn’t happen. Kidding.
I run these on all my vehicles, no drone ever in 4 different vehicles: https://www.summitracing.com/parts/...C_AVNHAULDPUqRG1GfWCVpJJxJk40MERoCBBwQAvD_BwE
So would I end the 2.5 section when the pipe gets to behind the wheel Where it heads to the bumper, put a reducer on the pipe and run 2.25 out the back? I’m wondering how much of the kinda expensive TA kit I’ll end up cutting out. The kit plus shipping was a lot. So far 13.75” is out for those resonators I got.
No, He is saying if you did 2.25 instead of 2.5. Try the resonator tips just past the bumper, worked for me. I had a H pipe crossover too.
Swap your tips for straight units. Lots of echo with the sound bouncing off the road and coming straight back. That made a big difference with my 66.
Pretend your a kid again with headers & Thrush, Cherrybombs, or Walker glass packs and no pipes after that!
I’m enough of a kid when I’m in my daily (that has axle back, coilovers, sway bars, body braces, and has to be driven in the most immature way possible). I was hoping be more of a grownup in my old Buick. It’s not working. Lol. I ordered some exhaust tips that have resonator baffling in them. I’ll see what effect they have when they arrive tomorrow. I’ll need to reconfigure the exhaust system a bit. I noticed yesterday that the resonators off the down pipes and the mufflers are too close to the ground. If I can get those higher it might be enough of an angle change that the tailpipes could be lower and that’d be better for the tip placement. I do think the current setup that points the sound at the ground is a contributor.
I had duals that had tips that pointed directly to the ground. I drove over a draw bridge in Buffalo with a metal grate for a deck. The car lost 2/3s of it exhaust noise with sound traveling through the deck instead of bouncing back up.
That is really interesting! We have some grated deck bridges around here, if I can just remember where they are. I’m going to try it.
