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Thread: Car Exhaust Drone Elimination

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    OK I have now fitted the J Pipes this week and this has most definitely brought the drone down by at least 4 to 5 db. At the "spot peak drone" around 1750 / 1800 rpm it sometimes momentarily touches 75dbm, otherwise it drops down around 73dbm or less. So yes a major difference no longer booming or heavy droning.

    A trip across town on the M1 with the missus in the car also proved to be comfortable, of course this was only about 30 minutes each way - a long trip over a few hours will be the true test to confirm as acceptable...

    I think I will look at other solutions such as replacing the rear cans with Borla's, the Borla V8 grumbling sound is what I used to have on my old Statesmen (but no drone) ... Borla categorically state no drone from their exhausts, for my caprice this will also be a custom fabrication job, a project for later date once I can find a committed person or place to do this.

    Many thanks to all who have responded to this thread.



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    Yeah Corsa Exhaust states NO drone technology as well but I still have it, I'll be looking into the J pipes set up too.

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    Quote Originally Posted by checkitout View Post
    OK I have now fitted the J Pipes this week and this has most definitely brought the drone down by at least 4 to 5 db. At the "spot peak drone" around 1750 / 1800 rpm it sometimes momentarily touches 75dbm, otherwise it drops down around 73dbm or less. So yes a major difference no longer booming or heavy droning.

    A trip across town on the M1 with the missus in the car also proved to be comfortable, of course this was only about 30 minutes each way - a long trip over a few hours will be the true test to confirm as acceptable...

    I think I will look at other solutions such as replacing the rear cans with Borla's, the Borla V8 grumbling sound is what I used to have on my old Statesmen (but no drone) ... Borla categorically state no drone from their exhausts, for my caprice this will also be a custom fabrication job, a project for later date once I can find a committed person or place to do this.

    Many thanks to all who have responded to this thread.
    Hi,

    I have a Quicksilver exhaust system fitted to a Range Rover Sport and have the dredded drone at low RPM's. Have been looking into solutions for this and was thinking of trying the exhaust wrap of the rear boxes, and also the crossover pipe, but now think the J pipe solution is the way to go first. WHere exactly on the exhaust system did you fit these? I have a dual pipe setup, but the only place for adding anything would be back at the rear boxes, and not a very long J pipe either. Also, which way should the J pipe face, forward or back?
    Any thoughts?

    Sean

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    From my experience I agree with you not to do the exhaust wrap... looking back now I am sure they did not work... if they did it was minimal.

    The J Pipes will definitely do a lot towards a fix provided you can get enough extra pipe in to match what the resonance calculation indicates - there are formula's on the internet... google and you will find it. I understand they need to be added before the rear cans (as is what has been done with mine) and ideally if possible at 90 degrees to where you interconnect them. Mine have not been done like this because of space issues and have a couple of J bends in and around the rear cans and pipe work (probably also why these are typically called J pipes) - It does not matter which way these pipes face as well... that I am aware of

    I hope this helps

    I will add that while I have had a big reduction in drone, drone is still creeping slightly when touring on slight/major incline or under load/quick revs. Not confirmed but I believe as I could not get enough length in for the J pipe (also as per formula) we did not completely eliminate the drone. In hindsight using a larger diameter J Pipe (matching 3 inch ILO 2.5 inch) would/should help.

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    Quote Originally Posted by checkitout View Post
    From my experience I agree with you not to do the exhaust wrap... looking back now I am sure they did not work... if they did it was minimal.

    The J Pipes will definitely do a lot towards a fix provided you can get enough extra pipe in to match what the resonance calculation indicates - there are formula's on the internet... google and you will find it. I understand they need to be added before the rear cans (as is what has been done with mine) and ideally if possible at 90 degrees to where you interconnect them. Mine have not been done like this because of space issues and have a couple of J bends in and around the rear cans and pipe work (probably also why these are typically called J pipes) - It does not matter which way these pipes face as well... that I am aware of

    I hope this helps

    I will add that while I have had a big reduction in drone, drone is still creeping slightly when touring on slight/major incline or under load/quick revs. Not confirmed but I believe as I could not get enough length in for the J pipe (also as per formula) we did not completely eliminate the drone. In hindsight using a larger diameter J Pipe (matching 3 inch ILO 2.5 inch) would/should help.
    Thanks for that. Mine is a 2" system, so was thinking of a 1 3/4 pipe to weld onto it. One thought I had was to weld a crossover pipe between the two section(left and right), just before the rear boxes. That way allowing gasses/sound to pass between them. Does this make any sense, or is it just a waste of time? The pipe would be about 30 inches.

    Sean

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    Ok some basics.

    I have met the tight arse Scottsman that owns Xforce at his factory (hint at what hes like)

    They are made in China, nice and shiny on the outside with rusty mild steel bits on the inside.

    They are tested here, i actually saw a development system being test fitted here on one of their hoists before sound testing.

    I know of exhaust shops that refuse to fit or touch their systems, they claim they are that bad (but its amazing how a shiny muffler can fool people.0

    Stainless systems ten to produce a higher pitch note, mild steel tend to be deeper noted.

    If you want to kill drone, cut the Chinese mufflers out and add larger quality ones. (or just add more quality mufflers while leaving the crap ones on)

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    Quote Originally Posted by SCar View Post
    Thanks for that. Mine is a 2" system, so was thinking of a 1 3/4 pipe to weld onto it. One thought I had was to weld a crossover pipe between the two section(left and right), just before the rear boxes. That way allowing gasses/sound to pass between them. Does this make any sense, or is it just a waste of time? The pipe would be about 30 inches.

    Sean
    Hi SCar

    I had my mechanics do this for me, unfortunately I can not say or advise other than my experience. As you will notice I am still working at mine with mixed results, I note a further message from Godzilla on this too (thank you Godzilla)

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    Quote Originally Posted by Godzilla View Post
    Ok some basics.

    I have met the tight arse Scottsman that owns Xforce at his factory (hint at what hes like)

    They are made in China, nice and shiny on the outside with rusty mild steel bits on the inside.

    They are tested here, i actually saw a development system being test fitted here on one of their hoists before sound testing.

    I know of exhaust shops that refuse to fit or touch their systems, they claim they are that bad (but its amazing how a shiny muffler can fool people.0

    Stainless systems ten to produce a higher pitch note, mild steel tend to be deeper noted.

    If you want to kill drone, cut the Chinese mufflers out and add larger quality ones. (or just add more quality mufflers while leaving the crap ones on)
    Thanks Godzilla, the feedback is much appreciated - I have my car going back this week for another assessment to have a better fix in place. I am contemplating simply ripping it out entirely as well if need be.

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    One other thing that crossed my mind.

    Check the hangers on the system.

    Look to see that they are hanging off rubber mounts.

    Quite often on poor fitting systems mounts can push upwards, into the chassis hanging points making drone. (noise)

    System is supposed to he hanging off the mounts on rubber, freely, jiggle the exhaust from the tail pipes and see if it knocks or swings freely.

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    Quote Originally Posted by Godzilla View Post
    One other thing that crossed my mind.

    Check the hangers on the system.

    Look to see that they are hanging off rubber mounts.

    Quite often on poor fitting systems mounts can push upwards, into the chassis hanging points making drone. (noise)

    System is supposed to he hanging off the mounts on rubber, freely, jiggle the exhaust from the tail pipes and see if it knocks or swings freely.
    Thanks for the tip, will check

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    Last week I changed out the X Force exhaust system from the Cats with a custom designed 3 inch 409 stainless steel setup. Dual system of course, 2 in line hot dogs per side and custom made (large as possible to fit) rear can exhausts.

    There still is a minor what I call "peak" exhaust volume at 1900 at times at rev or load... definitely not the drone and grone I used to frequently get, a definite improvement, and it definitely passes the important "Missus" test. Sounds great very throaty and deep V8ish.

    Doing some country driving at the moment and am able to chew up km and multi hour trips now without getting a head ache from the cycling drone and grone booming I would typically get before.

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    think of it as a drummer on a stage to stop the drum sound he puts his hand on it so use your head and duplicate what he does but dont burn your cheeks ????shorten the length with more hangers and your problem dissappears easy lol

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    Drone is a frequency so all you need to do is identify what that is and then work out how to 'Damp' it........Should keep you broke and busy for a weekend or 2.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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