Custom exhaust drone issue cure?

[LostKiwi]

I'd add an x-pipe. No guarantee it'll get rid of the drone but it has benefits in power and torque and who wouldn't want that?
The exhaust note will change with an x-pipe. It'll sound 'softer' as in less hard edged and under some circumstances can develop a 'howl' at wide throttle openings (which I found very addictive on my last x-pipe setup).

There are many designs of x-pipe:
This Magnaflow is my least favourite:

I'm not a fan of this either:

This is my preferred design:

The longer conjoined area gives a better compromise of torque and power. In cross section the pipe looks almost like an 8 with the central dividing line removed lying on its side. A pipe like that will almost certainly need to be custom made from scratch.
Something like this is available off the shelf (this was found on eBay) and is a reasonable compromise on cost:

 

[television]

In my case the box had been removed, so hence the big improvement with the X pipe.

 

[Borys]

Thanx
Will ring the shop and arrange a visit

 

[Borys]

Watch this guys
Still this may be the easiest way

https://m.youtube.com/watch?v=afwdv3Qwdpk

 

[television]

At least thats what I said as close up front as possible.

 

[Borys]

Shame that most of the exhaust shops in uk don't know how to deal with drone - matter of luck if they get it right. It would make systems so attractive without that unknowing bit - is it gonna drone or not he he
Hopefully I'll get this sorted, open a shop and make millions fixing other garages attempts

 

[Craiglxviii]

Shame that most of the exhaust shops in uk don't know how to deal with drone - matter of luck if they get it right. It would make systems so attractive without that unknowing bit - is it gonna drone or not he he
Hopefully I'll get this sorted, open a shop and make millions fixing other garages attempts

It's a huge industry in the States.

Over in Europeland we don't quite go in so much for classy exhausts, either stainless versions of OEM systems or silly loud poppy razzy types for Chavics and Scoobies.

 

[LostKiwi]

Watch this guys
Still this may be the easiest way

https://m.youtube.com/watch?v=afwdv3Qwdpk

Yes - its the same idea as the one you showed at the start of the thread.
If you implement a pair of them (you will need 2) I'd suggest inserting the elbow onto the pipe then having a removable remainder so you can tune the length. The Heimholz resonator like that will only cancel out resonance at one relatively narrow RPM range. You'll need to tune it according to where you want that resonance to go to.

This is also how an x-pipe can help - it changes the base pulse rate in each pipe. As you are now you have 4 cylinders down each exhaust but its complicated by the V8 firing pattern:
LRRLRLLR where L is the left bank and R is the right bank. Note the double pulse on each bank. Thats what gives the V8 its distinctive rumble but also makes it difficult for getting rid of droning.
By allowing mix of the left and right banks to a certain extent changes the resonant frequency of the exhaust.

 

[Craiglxviii]

Yes - its the same idea as the one you showed at the start of the thread.
If you implement a pair of them (you will need 2) I'd suggest inserting the elbow onto the pipe then having a removable remainder so you can tune the length. The Heimholz resonator like that will only cancel out resonance at one relatively narrow RPM range. You'll need to tune it according to where you want that resonance to go to.

All that warp plasma has to go somewhere and resonance is the best way for it to go.

 

[Borys]

OFFICIALLY I'M DRONE FREE!!!!!!!!!!!!!!!
30" j pipe cured my car. All drone is gone only the nice burble to enjoy now
Love it

 

[AMGeed]

OFFICIALLY I'M DRONE FREE!!!!!!!!!!!!!!!
30" j pipe cured my car. All drone is gone only the nice burble to enjoy now
Love it

View attachment 32313

Glad its sorted and you like the noise!
Just get those 63 boxes sold and it won't be so painful.

 

[television]

Good one

 

[alexanderfoti]

Excellent. I had a nightmare with this and my CL. Got a custom exhaust place. Secondary cats and resonators removed. Lots of noise and tiny amount of drone. Backboxes removed, HUGE amount of drone and absolutely unbearable on the motorway.

The exhaust place could never remove the drone and eventually put the backboxes in (after messing around with various configurations, costing me lots of money!). I read up about helmholtz tubes, but couldn't find anybody in the UK to sort them out.

Who did yours?

Of course, the best bit would be a switchable system, still trying to find somebody who will do a custom one of those in the UK.

 

[Borys]

I'm really puzzled with custom exhaust shops approach. I don't think there is a set up with after market boxes, etc which doesn't drone. Being an owner of a garage I would do everything to find a solution. Me as a customer - it took me 2 evenings on US forums, you tube and a solution was at hand.
Went to that shop today thanks God owner is a nice bloke and he listened. I literally prepared a presentation like for a high paid job ha ha. He said lets try it it make sense. Result - no drone!!!
I used Fast Lane Styling in Chadwell Heath, owner said he will use this solution for customers with "drone syndrom" he he
Now truly any v8 I will not be scared to go for a custom set up. I will exactly know where to place j pipe and how the whole design should look like.

 

[Submariner1]

I'm really puzzled with custom exhaust shops approach. I don't think there is a set up with after market boxes, etc which doesn't drone. Being an owner of a garage I would do everything to find a solution. Me as a customer - it took me 2 evenings on US forums, you tube and a solution was at hand.
Went to that shop today thanks God owner is a nice bloke and he listened. I literally prepared a presentation like for a high paid job ha ha. He said lets try it it make sense. Result - no drone!!!
I used Fast Lane Styling in Chadwell Heath, owner said he will use this solution for customers with "drone syndrom" he he
Now truly any v8 I will not be scared to go for a custom set up. I will exactly know where to place j pipe and how the whole design should look like.

Interested to know, is it possible just to remove the rear muffler on an M273 and substitute it with a straight through perforated silencer and a J pipe of 30"?
Does it matter where the J pipe joins the setup?

One link on this thread seems to suggest that drone would only be cured for the exhaust pipe after the J pipe junction. I.e. Any drone created before that would not be countered. That surprised me, as I thought it would not matter where the J pipe was cut into the exhaust.
I assumed, in my suggested setup; that one could join the J pipe just before the new replacement straight through muffler.
Would that work?

I know the maths calculation for the length of the J pipe but does the diameter of the pipe matter? ... most in the USA seem to use 2" J pipes.

Do you know what wall thickness the OEM pipes on a CL500 are? 1.25mm or 1.5mm.? And can one get 2mm thick tubing to counter the harsher sound of stainless steel?

 

[LostKiwi]

Interested to know, is it possible just to remove the rear muffler on an M273 and substitute it with a straight through perforated silencer and a J pipe of 30"?
Does it matter where the J pipe joins the setup?

One link on this thread seems to suggest that drone would only be cured for the exhaust pipe after the J pipe junction. I.e. Any drone created before that would not be countered. That surprised me, as I thought it would not matter where the J pipe was cut into the exhaust.
I assumed, in my suggested setup; that one could join the J pipe just before the new replacement straight through muffler.
Would that work?

I know the maths calculation for the length of the J pipe but does the diameter of the pipe matter? ... most in the USA seem to use 2" J pipes.

Do you know what wall thickness the OEM pipes on a CL500 are? 1.25mm or 1.5mm.? And can one get 2mm thick tubing to counter the harsher sound of stainless steel?

Calculation for resonant frequency of a closed tube:

Where v is speed of sound, L is length of tube, d is diameter of tube.

Yes diameter does matter.

 

[LostKiwi]

Excellent. I had a nightmare with this and my CL. Got a custom exhaust place. Secondary cats and resonators removed. Lots of noise and tiny amount of drone. Backboxes removed, HUGE amount of drone and absolutely unbearable on the motorway.

The exhaust place could never remove the drone and eventually put the backboxes in (after messing around with various configurations, costing me lots of money!). I read up about helmholtz tubes, but couldn't find anybody in the UK to sort them out.

Who did yours?

Of course, the best bit would be a switchable system, still trying to find somebody who will do a custom one of those in the UK.

If you talk to Ant at ARO exhausts he'll make up anything you want him to pretty much.
You can get the switchable exhausts online - you could get a couple, design what you want and ask him.

http://www.ebay.co.uk/sch/i.html?_o...0&_nkw=electric+exhaust+cutout+valve&_sacat=0

 

[Submariner1]

Calculation for resonant frequency of a closed tube:

Where v is speed of sound, L is length of tube, d is diameter of tube.

Yes diameter does matter.

Thanks so much, I got the formula from a guy in the US, very charming, but possibly not too "scientific" and d was just a ' 2' for now I know 2"s.
When pressed he said it doesnt matter, but we always use 2" pipe as my guy has a supply of really thick 304.

He did have a neat idea of making the capped end in a slightly wider tubing, so it could side over the main J pipe. I.e. It was adjustable. Basically he said they clamped it roughly at 28" but could then slide too and fro to "tune", in his words the resonance blocker! Once you were sure you had the right position ( he said he would run it for a week) then once happy a couple of tack welds in situ, to ensure the right position and no twisting strain, then whip it off and weld it up!

Please help an old guy out, its a very long time since I did Mathematics.

So L = .......

 

[Submariner1]

If you talk to Ant at ARO exhausts he'll make up anything you want him to pretty much.
You can get the switchable exhausts online - you could get a couple, design what you want and ask him.

http://www.ebay.co.uk/sch/i.html?_o...0&_nkw=electric+exhaust+cutout+valve&_sacat=0

Thanks that is ARO in Buckingham MK18?

Love the idea of the electric cut out .... but do they freeze up quite quickly?

 

[LostKiwi]

Thanks that is ARO in Buckingham MK18?

Love the idea of the electric cut out .... but do they freeze up quite quickly?

Yes thats Ant. I have no idea regarding reliability of those cut outs - but I do keep thinking about them for my SL...