Resonator placement

[c1500sbc]

I have an s10 with a small block/weiand 144 combo, shorty headers with “true duals” dumped out before the rear axle. Mufflers are some flowmasters. The truck sounds good, not super loud, but the drone is absolutely unbearable. I’m looking to add a couple of resonators to the exhaust to help. Trouble I’m having is placement. Without redoing the whole exhaust it’s tough to place them before the mufflers. I’ve never had a vehicle with the resonators after the muffler. In my case, I would likely just put them directly after the muffler (easiest way to do it).

Is it just a difference in sound putting the resonators after the muffler versus before? Is this considered a no no in the performance world?

[Steve K]

what about just changing out the mufflers for UltraFlows or a similar type of muffler. I just installed Flowmaster FX's on my Camaro and they're not to bad drone wise. They are on the loud side though. They typically make little to no drone and it's an easier swap than trying to fit resonators that may or may not get rid of the drone.

[c1500sbc]

Well I was honestly thinking of that as well, but I’m worried that the drone is just a characteristic of the engine. It happens at a very specific rpm range

[BOOT]

First off flowmasters the chamber type, have been track documented to loose ET. Still that said some prefer a sound or big wheels n such.

I've always read the tips need to go past the body to help prevent drone, not sure how yours is.

If you got room to add after why not move the muffler back and try resonator right before? I realize this would be more work but not a total redesign maybe if it's possible to do that.

Basically all the hi-flow perforated tube bullet type mufflers(like flowmaster FX) are resonators and don't reduce sound much.

Seems many want max power but not the sound that comes with it and I suppose as i get older i am leaning toward the same. So i may need to start using real mufflers someday at a bit of a power cost.

Well if you do try it then let us know how after works.

[F-BIRD'88]

Change the mufflers. dynomax super turbos are not bad. Add tail pipes, exit at bumper or behind rear wheels.

[rgalajda]

Change the mufflers. dynomax super turbos are not bad. Add tail pipes, exit at bumper or behind rear wheels.

This is your best answer

[BLSTIC]

I've heard an X or H pipe can dramatically alter drone frequency.

Plus, sounds more racecar

Alternatively if it's one specific frequency, quarter wave resonator or "j pipe" can cancel out a narrow frequency range pretty well.

[RCJ]

I'm with the add tail pipes and h pipe crowd.

[Steve K]

Well I was honestly thinking of that as well, but I’m worried that the drone is just a characteristic of the engine. It happens at a very specific rpm range

The drone is a resonance within the muffler tuning (baffles) based on RPM. I had a 89 Mustang GT that had Walker Super Turbos and the drone was nuts right at cruise rpm (around 2000RPM). Before and after that they were fine. No drone in factory mufflers. No baffles in straight through mufflers so not much there to cause drone.

[Bill Chase]

Dynomax super turbo 3" mufflers are very good quality and do not choke down to less than 3" inside. About $125 each.

[F-BIRD'88]

Drone is not caused by baffles in the muffler. Drone is caused when the sound at a specific frequency (engine running speed) excites,vibrates (resonates) the underbody floor pan. Amplified by dual exhaust with same pipe length and muffler position. Especially when the exhaust exits under body. Lack of tail pipes.
Poor muffler design.

[Chris_Hamilton]

Drone is not caused by baffles in the muffler. Drone is caused when the sound at a specific frequency (engine running speed) excites,vibrates (resonates) the underbody floor pan. Amplified by dual exhaust with same pipe length and muffler position. Especially when the exhaust exits under body. Lack of tail pipes.
Poor muffler design.

The various aftermarket mufflers available cause the change in frequency. The frequency that it oscillates at is dependant upon the engine being used. The end result is similar to what you described. Same muffler on one engine might resonate (SBC) at the specific frequency. Same muffler on say a Porsche flat six might not.

Porsche's for example have a rather unique exhuast system that doesn't fit the parameters listed above. Yet they too will resonate depending on the muffler used.

[F-BIRD'88]

Mufflers don't cause drone noise. Bad design muffiers fails to suppress exhaust drone noise. Lack of tail pipes allow the floor pan to resonate driven by the exhaust sound . Exhaust exit under car is a real bad idea in more ways than one.
Net car performance will increase and drone will be eliminated by Tri flow type turbo mufflers (Dynomax or Sonic Turbo) and adding tail pipes.
2-1/2" exhaust is plenty big for this job. 3" is going to be louder than desired. The shine comes off a loud annoying exhaust system quick.
Ditch the Flowmasters and add tail pipes.

[Warp Speed]

Put a cross over or X pipe in it. It will sound AND run better!

[cab0154]

The drone is the flowmasters. thats what chambered mufflers do. get something straight through like an ultraflow, or of you really want quiet get a turbo muffler, but the turbo muffler might kill a little power.