Exhaust Drone - Hemholtz Resonator or J-Pipe Application

[19TXLimited]

Hey there everyone, has anyone installed either the straight pipe system, or Flowmaster Outlaw and incorporated a Hemholtz resonator / J-Pipe in order to eliminate drone?

I have had a Toyota Tundra in the past with a straight pipe system which incorporated a Hemholtz Resonator to eliminate drone...the Tundra does not use resonators to quiet things down, but with the use of the Hemholtz there was zero drone on the highway with a straight pipe exhaust. I am uncertain this would work due to the V8 to 4 switch...not sure the "drone" frequency would remain the same and only become louder, or if the frequency itself changes causing the need to use multiple hemholts resonators in unison.

I may also try to make a custom exhaust using a muffler and Hemholtz resonator from BAMuffler which is very popular with the Tundra community as B2 Fab is here, however, they use their own in-house mufflers.

Anyway, any input would be appreciated and maybe this post will help others who are wanting a screaming exhaust, but also eliminating the factory rear resonators and replacing with a Hemholtz or two.

 

[Ram_Feste]

I designed and put one on my 13 Raptor a year or so ago. Most muffler shops don't know what you are talking about, but I found a shop finally that worked with me/my design as I wanted to be able to tune the jpipe/helmoltz to suit my hearing. So I had them flange out the last portion towards rear of cab and put another piece of pipe that we welded on a cap then I could slide either way about 5" to tune out the drone. I got lucky on first attempt as I did measure out length and matched the drone frequency with about 2" pushed into the pipe (3" still showing). Can PM you a pic if I can find it.

 

[19TXLimited]

I designed and put one on my 13 Raptor a year or so ago. Most muffler shops don't know what you are talking about, but I found a shop finally that worked with me/my design as I wanted to be able to tune the jpipe/helmoltz to suit my hearing. So I had them flange out the last portion towards rear of cab and put another piece of pipe that we welded on a cap then I could slide either way about 5" to tune out the drone. I got lucky on first attempt as I did measure out length and matched the drone frequency with about 2" pushed into the pipe (3" still showing). Can PM you a pic if I can find it.

PM a pick if you have a chance. I know Keith with BA Muffler said he used a similar approach. He said the Tundra exhaust note is pretty horrendous...especially when straight piped, but he was able to tune out all drone with the Hemholtz. I want to say he was somewhere around 26 inches for his application. He also told me that location of the Hemholtz plays a major role and that with these trucks it might be necessary to have 2...1 for V8 and another for MDS (4banger). It all sounds like a pretty awesome idea, but right now I am unsure whether I am wanting to put all the effort in to come up with something.

Keith is located out of Escondido CA. If there was someone on the forums willing to work with him direct I'm sure he would be willing to put in the work to make the perfect exhaust for our trucks. My biggest problem with it would be getting the muffler size correct for the perfect sound and then knowing where to place the Hemholtz in order to then tune it for V8 or maybe even just tune it for MDS since that seems to be where all the drone is.

Keith uses a barrel style muffler for his Tundra systems which utilizes two (2) 8 inch mufflers. He believes something about 14-16 would be perfect for the Ram and that the style of muffler will help a bit to remove drone within itself.

We will see whether I take on the adventure. If I do there will be plenty of pictures posted up and try to work with Keith on getting a system into production.

 

[Samiam44]

This is interesting stuff. One point that is not correct, exhaust gas temp. We want the air temp in the j-pipe or hemholtz resonator which is different. The hemholtz is more complex than a simple equation. The total transmission loss and the frequency range are affected by geometry.
Naca rp 1192, figure 12, figure 28 which is more of a j pipe. Very small range and it's 20db loss peak. Go over to an ideal hemholtz and it's 35 db, 10 db over 75hz and 5 db 50hz higher! Fat short drum w a short neck. Here I would guess some 5 + in pipe with a short neck.
Best jpipe someone guessed temp at 160f, and it was near the down pipe. Measured temp was 170f, his fabricated length matched. He should be getting 15-20db reducing at the peak.

This is why those automotive acoustic engineers earn their keep. Tr 1192 doesn't cover it all and I wasn't smart enough to calc my geometry. I'm trying the j-pipe first...