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Inches, degrees F. What about some Metric Units. We are not all in 3rd world countries. S.I Units have been in use since 1970. (System International). You are trying to use BOTH, unsuccesfully.

is this work for crf450x 2009

Is it possible to sleeve a pipe concentrically within the exhaust pipe that is the required length for ¼ wave with a capped off end and achieve the same the result?

Oh my God finally! Years I've looked for this. Decades! Finally! Thank you so very much.

Great video, one question I have, does the J pipe need to be the same diameter as the main pipe? can you go larger or smaller?

Does the qw resonator work the harmonics in lower frequencies? If i make a pipe thats for 120 hertz, will the resonator also cancel out the frequencies at 60 hertz?

I’m watching this to fix my droning, but something you said just flipped a switch in my head. You solved my problem with my tweeter sound reflections. Thank you sir

Great video. I have a question that I'm pretty sure I know the answer too, but I want confirmation. If you have a true dual exhaust setup, you would need the J pipe on each side correct? I have a Porsche Boxster and the exhaust sides don't meet until the muffler.

Very helpful. Thank you. Just bought a used crf250X with a tusk street kit and an ignition key switch. Some of the components were not wired properly and this will help in putting the bike together.

How does the diameter of the pipe affect a J Pipe? Amazing video btw, thank you!

sick job mate ! my ears will thank you forever ! try this as soon as possible !

Use your calculations and it's dead on. No more drone, I am loving it.

Hey guys, just looking for some help. I followed the video instructions and downloaded the app, but at peak drone, the app said the frequency was in the high 300s, low 400s. Obviously this is very high as everyone is finding readings in the low 100s. I tried to use the theoretical calculator, however, because I have a V6, I interpolated and it was in the 120s roughly. This is causing a major discrepancy in the pipe length. I was hoping if anyone can help with some advice. Could the reading on the app be wrong? (Most likely)

Thanks for sharing!

29:06 so the total length of that bent jpipe installed was 61 inches? I drive almost the same car (8th gen civic) almost same level of drone based on the video & same rpm level (about 2k when drone starts to irritate my ears)

U did sth wrong there ,After the upgrade on your video, I still hear resonance, and exhaust temperatures are changing too . U dind show spectrum after upgrade . Placebo?

Does the jpipe have to be the same diameter as the rest of the exhaust?

Now put the stock muffler back on and it will be really quiet lol. I'm officially old.

So if you have a dual exhaust, meaning two headers coming in and joining in an X pipe, then running dual pipes out, do you need two 61 inch j pipes? one on each exhaust pipe?

good work, I'd love to see the spectrum analysis afterwards

I have a 2006 450X and this seems to be exactly the same wiring as my bike, been searching and searching then finally found this video. Thank you very much for the meticulous walk through and details.

Dam man great video

If you cut the j pipe size in half… what happens?

How large in diameter should the J-Pipe be?

I wonder if this would work on my EV?

Could you make that J pipe like a sliding assembly like a trombone so you could dial it in when you find that drone and then stopped it there is it could you make it adjustable

thanks so much for your effort of explaining this. I have a question however, does it not matter where in your exhaust you put the pipe? like wether you put it right before your muffler or after the headers? maybe that would change how long the pipe needs to be, so you can run a shorter one for weight and space reasons?

Great video! 👍🏻

How does this calculator work with a 13b rotary engine with 6 pulses per revolution? Im trying to eliminate drone at 2500-3000rpms @100hz peak frequency Thanks

Great video. What app are you using to measure the sound?

I presume adding the resonator to the system as close to the engine as possible would be ideal. This would attenuate the resonance (drone) after the shortest distance reducing the amount of your exhaust system that will be vibrating in time with the resonant throbbing of the exhaust gas. Or do the out of phase pressure pulses travel up the pipe far enough anyway? Do they make it back to the valves? I expect in most installations this irrelevant as you are likely to be limited by the cars under body configuration (space). You were doing so well until you said the calculation of frequency from RPM was less accurate than using the app. Yes different engines have different tones but YOU identify the RPMs where drone occurs by ear, and the cars Taco. It is a subjective observation not a measurement. So it's you (and the cars Taco) not the Math or physics that is the source of error. If you identify the RPMs correctly then the frequency CANNOT be wrong. Regardless of Honda or Subaru, a drone at 2250 RPM is due to a resonant frequency of 70.8Hz. I found the Apps gave inconsistent and different results. If your App shows multiple peaks how does average Joe know which peak Freq. is the one that is annoying him. One App I tried was completely wrong. Ultimately I think using both is the right solution. It is after all a range of frequencies you are looking to dull, and the ideal resonator length varies with driving conditions due to temp anyway. So a few Hz resulting in a few millimeters is irrelevant. Oh and measuring the temp in the tail pipe (not so much). It's the operating temp of the gas inside the (not yet existent) resonator that matters. This is impossible to measure and hard to work out as there are SO many variables. It is functionally substantially different to the tail pipe. The exhaust gas doesn't even "flow" through the resonator. It just vibrates around inside the J tube. Still one of the best vids on this topic.

Gosh, I miss my engineering.

Question, what happens if i dont have enough space for the full length? I need around 33 inches (calculated) and my space is for around 12 inch. Will it do something?

its 30 degrees f right now and my tundra is reading 145 degrees. should I wait until its warmer? how off will this be?

Looking at your excel table, I see the length is being calculated by (Speed of Sound/Frequency)*(1/4)*(39.3701). Where is the 39.3701 coming from? Maybe I missed it somewhere in the explanation.

God i love it when nerds are car guys! Thank you for educating me on this. I just picked up a 23 passport and im looking forward to modding it.

You Can Literally See How The Drone Was Eliminated. His Camera Isnt Shaking Anymore

Measuring Drone Hz Vs Calculating Hz. In Your Example They Matched Pretty Close. Is This True If The Exhasut Already Has Glass Packs / Mufflers Or Do Those Skew The Drone Hz Calculations Vs Drone Hz Measured? I'd Imagine Glass Packs Only Muffle But Some Mufflers With Baffles Could Maybe Change The Drone Hz????

There must be some shortcut or a straight formula to do all the math without going too much in details. Any comments ? I am looking forward to attach a J shape resonator with my straight pipe muffler to reduce its loudness

How would this work with a dual exhaust. Would I divide the pipe length between 2 pipes or make them both the size on th chart ?

So, I’ve got a 13 civic si so same 9th gen with same motor. The current exhaust is 3 inch. The painful drone level is when it hits 140hz. Normally I’ve noticed that from letting it coast off throttle. 70hz cruising. Would running the same length piping eliminate that as well if I’m understanding correctly?

Great explanation and video! How do I choose the diameter of the J Pipe, I've seen other guys using a slightly smaller diameter pipe than their exhaust.

I have a 3.5" single exhaust and results turn to be 36" pipe length needef to J-Pipe. I can only fit a largest diameter of 2.5" for J-Pipe for 36" length. What would be the correction factor from using a smaller diameter pipe? I'm assuming the wave would travel faster in a smaller diameter pipe or am I thinking this the wrong way and velocity of exhausts gases would only travel faster and wave is unaltered?

Is this similar for a 230f 2005

Does grounding the ignition (As in pressing the kill switch or having the key OFF) drain the battery at all?

This is amazing and so informative. It's exactly what I was needing to see.

Some people need adding a J-pipe to their throats.....

Hey Alex I don't remember hearing youth say how much it cost to have that built and installed. Do you remember approximately what it was? Im doings this on my subaru before we leave to Virginia beach in 3 months

Don't play with your phone while driving, you idiot. Specially on a mulit-lane public roads. Ask a friend to do that for you.

you have 2 J pipes in your ears, it helps millennials reduce the outside world sound, so they can be more autistic