Car Exhaust Drone Elimination

[checkitout]

I have my new 2016 Caprice fitted with a Xforce sports exhaust. Unfortunately I get a bit of exhaust drone from about 1700 to 2000 RPM.

My mechanic is stumped, especially as we added an extra muffler to bring down the sound exhaust level. Is there somewhere in Melbourne that specialises in removing Drone from after market sports exhaust systems. I have googled and found that custom built "tuned" resonators will fix the problem.

My mechanic will make a call in to Xforce soon however I have a gut feel that it will not go far towards a fix

[mandc]

I had a similar problem a few years back when part of the exhaust was replaced with aftermarket mufflers/pipe...2 hotdogs in series to replace the factory muffler. It was a V6 but went to a single pipe out the back.

It was eventually fixed by adjusting the hangers holding the exhaust..one was either removed or moved to a different location...can't remember which but it fixed it immediately.

[checkitout]

Spoke to my mechanic- he reckons there is no physical room to add resonators to tune out the drone

After a bit of googling I noticed someone mentioned in another forum having a similar problem which he primarily fixed by putting an old doona across the boot area of the car - seems weird. I have put a rudimentary old blanket that I managed to pull out from the missus's linen cupboard when she was not looking and while it has not eliminated the problem I am sure it has reduced it.

I am now thinking of getting my hands on some more professional sound proofing material make this more permanent and maybe more effective - Does anyone have any experience or advice here ?

[Splinter17]

If you get your exhaust guy to fit a crossover pipe section just after the firewall that should do it.

(I am guessing you have a full twin system)


Also exhaust wrap the two rear sections and secure with stainless cable ties....if needed

[gordon_s1942]

As the drone is coming from the actual exhaust itself, any sound deadening material inside the car will reduce it.
You'd get the same effect by wearing a set of headphones.

To me this sounds like a frequency resonance like when you pluck the strings on a Guitar but in this case, its the gases flowing from the engine and as you speed up the engine, thats causing the exhaust to vibrate.
Could you put the car on a hoist and run the engine up to speed and go along the exhaust to see where its coming from then using something like a pipe clamp to brek up that vibration?

[lsemmens]

I think splinter's suggestion will work most effectively because the crossover will affect the resonant length of the pipe.

[checkitout]

If you get your exhaust guy to fit a crossover pipe section just after the firewall that should do it.

(I am guessing you have a full twin system)

Correct yes this is a full twin system.

Question ... What is the theory on the effect on resonance by installing at this point and on why this would work?

[checkitout]

Also exhaust wrap the two rear sections and secure with stainless cable ties....if needed

Exhaust Wrap ? I appreciate the suggestion especially if it works, how durable or quality material is this exhaust wrap, I do not recall seeing this used before

[hoe]

the xforce exhausts are made in china.
unfortunately this means they are probably not tested on a car at all, just made to a pattern.
it would be a bit of a lottery as to whether they perform well or not, particularly on a new model car.
i know someone who fitted a system to an srt8 chrysler and actually made less power and more noise than a stock system.
I had my srt8 fitted with a dyno tuned stainless cat back magnaflow system, $1150 delivered from the states.....

personally i would remove it and demand a refund.

plenty of aussie made systems around that perform properly with no drone.

[Splinter17]

Exhaust Wrap ? I appreciate the suggestion especially if it works, how durable or quality material is this exhaust wrap, I do not recall seeing this used before

If you do both as I suggested then it will cut the drone, maybe not all of it, but you paid for a loud exhaust...so you got one....

[checkitout]

If you get your exhaust guy to fit a crossover pipe section just after the firewall that should do it.

(I am guessing you have a full twin system)


Also exhaust wrap the two rear sections and secure with stainless cable ties....if needed

I checked with my mechanic and it already has a crossover "X" pipe fitted.

As it it is not a major expense I am going to work on first getting sound proofing done across the boot area and see what the drone is like then.

The exhaust wrap will probably be the next option.

[checkitout]

the xforce exhausts are made in china.
unfortunately this means they are probably not tested on a car at all, just made to a pattern.
it would be a bit of a lottery as to whether they perform well or not, particularly on a new model car.
i know someone who fitted a system to an srt8 chrysler and actually made less power and more noise than a stock system.
I had my srt8 fitted with a dyno tuned stainless cat back magnaflow system, $1150 delivered from the states.....

personally i would remove it and demand a refund.

plenty of aussie made systems around that perform properly with no drone.

Thanks - I had a defillipa exhaust on my previous Statesman, 2.5 inch full system including extractors - loved it... no drone at all.

Was your Magna flow 2.5 or 3 inch btw

[hoe]

3 inch twin system to suit challenger 392

[Splinter17]

I checked with my mechanic and it already has a crossover "X" pipe fitted.

.

Put a second crossover just before the diff.
(assuming you want to fix it rather than just buy a different setup)

[checkitout]

Put a second crossover just before the diff.
(assuming you want to fix it rather than just buy a different setup)

Thanks, I can not be bothered changing to another setup ... this is another fallback option to use if I need it, I will post back results.

[checkitout]

If you get your exhaust guy to fit a crossover pipe section just after the firewall that should do it.

(I am guessing you have a full twin system)


Also exhaust wrap the two rear sections and secure with stainless cable ties....if needed

Hi Splinter, when you are referring to the the two "rear sections" is this the pipe work from the rear mufflers going back returning towards the front? Assuming I have read this correctly, what is the theory behind this?

I much appreciate your feedback here

[mtv]

Splinter17 has been banned, so he won't be responding.

Nothing related to this thread though.

[typan]

the only way to fix the drone is to fit J pipes if you have the room, google it

[checkitout]

the only way to fix the drone is to fit J pipes if you have the room, google it

Thanks for response - I have been done a bit of Googling on drone issues and yes J Pipes come up as a fix a lot of the time.

Honestly I am a little over the issue, but there has been a lot done and some mixed success since I last posted.

There following is what has been done, I can supply pics if anyone is interested.

1. Sound Deadener,
Rear boot and especially the rear parcel shelf. The spare tyre well is simply a plastic "insert" ... it was like having a near muffler next to an open door

Rear seat floor and rear seat kick board - the rear seat kick board in particular was thin and vibrating, muffler or muffler pipe heat was easily felt as well through the spots directly on top of inside the car.

Sound deadener on the above brought down the inside car noise at peak resonanc (at approx 1800 rpm and under load) by about 2 to 3 db (was easily getting up to 82 or 83 dB)

Thankyou to South East Car Audio Dandenong with help and advice here

2. Exhaust Wrap
In my view this seems to have done little or nothing - the sound "tone" seems to have changed and is more deeper and comfortable though. Both the 2 rear cans as well as a mid muffler and mid catalytic converter done.

Most definitely the 2 items above (apart from at peak resonance) has brought the sound levels inside the car to be a lot more comfortable - the missus has actually started talking to me again while I am driving around town. I still need to do a long trip and see if I can bear with how bearable the droning is on long stretches now

I have this as a work in progress, J Pipes is a bit of effort and cost to do, so far no mechanic will guarantee anything apart from charging me $$$!
I am thinking of testing some weight dampeners on the exhaust in different locations (trial and error), again a work in progress, plenty of info on the internet on this too.

Dropping in to a specialist exhaust shop that is experienced in removing exhaust drone is also high on the list ... just need time (and more money)

Thanks for reading - any feedback ideas or possible suggestions for fixes will be great

[checkitout]

the only way to fix the drone is to fit J pipes if you have the room, google it

I have finally found a local specialist confident to fab and fit a set of J Pipes ... just waiting to get a time to book it in.


On another point on taking the Caprice on a Melbourne to Sydney trip this week I have found a semi work around ... on freeway cruising and in sports mode I switch between 6th and 5th gear manually .... this shifts the RPMs away from the dreaded 1800 RPM drone zone .. drone goes ... incredible difference. Yes this is a small sacrifice on fuel economy ... but saves my head ... the paddle shift works a treat to switch between as well

More news on this once the J Pipes get installed