irokdastar

I want to redo my exhaust . I removed the secondary cats , resonator and OEM muffler . I added 2 exhaust cutouts where the secondary cats where and added a Magnaflow dual in dual out muffler where the resonator used to be . This way i can open the cutouts for full open exhaust and close them when i want it to be quite . The only issue i have is the drone . particularity from 1700-2200 rpm . this is usually annoying on the highway . I saw some who did J pipes and 1 person who did it on an E-Class . I wanted to see if anyone did it on a clk and if it really made a difference and what size j pipe was used . Thank you

Red,

irokdastar

I have that already . Its a cutout . I am looking for J pipe that Quiets down the drone . Thank you

2MCHCAR

I'm in the planning phase of updating my exhaust and the inclusion of the J pipe is one thing I'm looking into. By my research, the pipe length can be determined via a formula and you can either use a frequency or engine RPM to target the range of sound you want to eliminate. If you google "jalopnik" and "J pipe", you will find a article about the J pipe formula using the engine RPM, there is another forum that explains how to determine the length using frequency (you have to record the drone, then use a sound analyzer to determine the frequency); I'm going to use both formulas to verify that the lengths are about the same. I will report back when I'm done in a few weeks.

irokdastar

That sounds great . I was reading on a j pipe install on a e500 and they said they used 29" J pipe . My only issue is I have a true dual and there isnt alot of room in these cars for dual exhaust .

Fatz

When you check for your drone points;
1. Please let me know if your peaks are not at 1975RPM and 2500RPM for your V8
2. You should check it on normal relatively flat road and on an incline; the resonant frequencies may be different.

You're much too far away for me to seek you installing a clamp on unit I have developed to address drone and to modify the exhaust tone.

Your drone will probably be around 132Hz and maybe 118Hz if there are 2 prominent frequencies.

irokdastar

Hello Fatz . The drone on the V8 is 1900 - 2100 RPM . This was done on a city road and highway. Can you show a picture of the clamp you created ? and what do you think length of pipe i will need ?

Fatz

I don't know a great deal about J pipes. I believe they target 132hz for reduction or elimination by using a reflective wave or a standing wave in the added pipe. For a reflective wave using 1/4 wavelength the length of the pipe would be ~10.97 inches and for 1/2 wavelength and a standing wave it would be twice that.

The device (Dynamic Vibration Resonator) I have been developing uses destructive interference without being in the gas flow path. It is this device, rather than the clamps that secure it, that I was referring to. The prototype core is 9.5x6x1.3 or 6.5x6x1.3 inches with a connecting rod, which passes through the core unit, of 13 inches. I'll try to upload a couple pics.

Fatz

Dynamic Vibration Resonator...

irokdastar

interesting do you have any video with sound comparison ? If it works i would want to buy or even test it out for you .

Fatz

I plan to make a few videos after the next round of rain here. I will post links to a couple and in interested we can go from there.

irokdastar

Great Thank you