Quieter exhaust needed.

[Spriteracer]

Hi all.

I have an E86 3.0si build date December 2006.

Contrary to many on here I'm after a quieter exhaust. I very happy with the glorious 6cyl howl when the revs go up at playtime, but the constant resonant boom at motorway cruise speeds and lower revs power-on is getting very wearing - enough to consider not using the car for any significant trip which would be a pity as I love it otherwise. A new BMW system would be uneconomic, and so I was looking at the Direnza system however their own advice seems to be that it will be noisier and they suggest track use only. Most other aftermarket systems seem to increase noise as well.

Another possibility might be to open up the boxes and repack them. I will also put some sound deadening on the floors / boot but not sure that will be enough.

I'm assuming my system is unmodified as the drone seems to be a pretty constant complaint. All the hangers and the vibration absorber seem to be intact.

So, any suggestions for alternatives ?

Thanks in advance (and hope!)

 

[GAZA62]

This may be a stupid question but I take the foam has not been removed from the sound generator as this can get annoying after a while I put mine back in and I have no noise issues even with an Auto which can drone on motorway journeys if the exhaust is on the loud side

 

[thecremeegg]

First time I've heard of the standard exhaust droning personally - you can barely hear it in the car at high revs normally?

 

[Spriteracer]

Thanks both.
I have removed the sound generator completely and blocked the holes, though that made little or no difference. It had both foams in.

Interesting comment "thecreamegg" . It doesen't drone at high revs - 4 to 5k+ but is particularly bad around the 2.5k-3.5k cruise. That speed /revs really seems to excite the resonance particularly.

 

[Davz]

Either you have very sensitive hearing or there is something wrong with your exhaust system. There is drone at 1.8k to 2k when under load in top gear but not anywhere else. At 2.5 - 3.5k cruising should be whisper quiet. Has your back box been butchered by dlv?

 

[ph001]

Agree - your exhaust must have had a mod at some point in it’s life. I would look at a breakers for a used replacement.

 

[dhobbs]

Do you still have the original exhaust?

Has the rear box been modified? Telltale signs would be the pipes being cut just before the back box.

Mine drones a little around the 2k Mark, but then that means I'm labouring the engine a little. Drop it down a gear

 

[Spriteracer]

Thank you all for your comments. It certainly sounds as if mine is not right or has been altered in some way. The noise is bad enough to make using the radio difficult. I will be having new subframe and diff bushes fitted in the next couple of weeks which will give us a chance to have a good look at it. I'll get the garage to sort the corroded system to manifold bolts at the same time so a change would then be an easy diy job.

 

[R60BBA]

The standard 3.0si exhaust has a slight drone at 70mph, which is exacerbated by any aftermarket system.

OP, if your exhaust is standard and you cannot take the drone I suggest you drive in such a way that you avoid the drone spots or turn up the music.

You will be wasting your money with an aftermarket system, as it will only make it worse.

As others have mentioned, if your exhaust has been modified look for a used one from a breakers...

 

[skelters]

Could you get in touch with the previous owner to find out what they might have done to the exhaust or any othe mods?

You could perhaps look at some sound deadening for the doors too.

 

[Anonymous]

+1 for it probably being modified previously or damaged in some way.

 

[Spriteracer]

Thanks again.

The drone / resonance is quite bad at any sensible motorway speed (say 60-80) and gets much worse accelerating from 60 or 70 in 5th or 6th gear on the flat so not labouring. Even worse when it is labouring. Good call on the door insulation as that would also help the general road noise.

I bought the car from a non-specialist dealer 14 months ago, so no chance of asking the PO. From what I've found since, not a particularly caring one either.

The next step has to be a thorough inspection when I can access it and then decide if it can be corrected. Has anyone cut open the boxes and repacked ? I'm wary of buying and unknown 2nd hand one which would in all probability be as old as mine.

 

[Anonymous]

Thanks again.

The drone / resonance is quite bad at any sensible motorway speed (say 60-80) and gets much worse accelerating from 60 or 70 in 5th or 6th gear on the flat so not labouring. Even worse when it is labouring. Good call on the door insulation as that would also help the general road noise.

I bought the car from a non-specialist dealer 14 months ago, so no chance of asking the PO. From what I've found since, not a particularly caring one either.

The next step has to be a thorough inspection when I can access it and then decide if it can be corrected. Has anyone cut open the boxes and repacked ? I'm wary of buying and unknown 2nd hand one which would in all probability be as old as mine.

There's a lot of these mods on the road at the moment where the original box has been cut, modified and repacked. One very quick way to check if this has been done to yours is to inspect the 2 pipes at the back of the box. If the box has been removed the pipes will have been cut and put back together with exhaust clamps like the ones in this picture. If the pipes haven't ever been cut then maybe you've got some bad rust somewhere...

 

[earthdweller]

I have a back box mod as you describe

It doesn’t drone .. under light loads and at motorway cruising speed it’s no noisier than the original exhaust system

So I think the OP has some other issue with his

 

[MDUBZ]

I went to see mike today (DLV) to get my roof motor fixed and relocated and also had my back box modified :?

Having read this post last night re drone I was slightly worried.. I needn't of worried: I had a 300 mile round trip and i tested running at various speeds in 5 mph increments from 50 (thanks roadworks on M6) to 70 and 70+ on the return leg - At constant speeds there was zero additional drone over the standard box, with about 2cm of pedal press i.e. slow acceleration there was a bit of a drone, but bloody hell when you drop a gear (or 2) and give it some, it sounds pretty meaty with plenty of burble on over run (faint in 6th) and a bit of a fart between gear shifts when gunning it - stock definitely doesn't do this.

I either cruise or give it the beans so i have no issue.

ps. he now has a stock back box if you need one

 

[Mr Tidy]

It definitely sounds like "Spriteracer"s exhaust has been modified in some way.

My last 3.0Si had been fitted with a custom cat-back system and sounded great under load but didn't drone, although it did produce some lovely crackles on down-shifts!

I wouldn't worry unduly about buying a used one, so long as it has never been opened up - the OE exhausts were stainless.

I just hope the OP can find a solution he can live with.

And I wish I could get a bit more straight 6 volume from my 330i. :lol: