Exhaust drone

[SteveMJ]

Hi all,

I need some help and advice to mute the effect of the drone due to my Walkinshaw Sports exhaust on my VXR8 auto. I recently asked about this (http://www.pistonheads.com/GASSING/topic.asp?h=0&t=1470051&mid=0&nmt=VXR8+with+Walkinshaw+-+drone+%3A-%28) and missed the one that Roger (S800VXR) had for sale.

What I'd like to know is:

What is it about other exhausts that do not cause drone?

Does the Walkinshaw switchable exhaust also drone, is it on both settings?

Can the standard exhaust be modified to allow more of the V8 melody through without that drone?

Hopefully you can see where I’m going with this; I have two exhausts, the original quiet stock one and the drony Walkinshaw and am looking a way ahead. Neither is very satisfactory at the moment :-(

Help and advice would be much appreciated :-)

Steve

[MyM8V8]

You could consider a lower diff ratio to get the drone range out of the cruising rpm?

[r-kid]

I think this was rich24's solution.

http://www.lotuscarlton.co.uk/vxr8ex.htm

[djwilk]

Or cruise at 85mph, some say...

[MyM8V8]

r-kid said:

I think this was rich24's solution.

http://www.lotuscarlton.co.uk/vxr8ex.htm

Hadn't seen that before. I really appreciate well thought out mods and proper engineering. Fantastic.

If he kept the jigs, I wonder if he can make more?

(Having said that, does the stock VXR8 OEM exhaust drone???)

[ARAF]

MyM8V8 said:

r-kid said:

I think this was rich24's solution.

http://www.lotuscarlton.co.uk/vxr8ex.htm

Hadn't seen that before. I really appreciate well thought out mods and proper engineering. Fantastic.

If he kept the jigs, I wonder if he can make more?

(Having said that, does the stock VXR8 OEM exhaust drone???)

Stock doesn't drone, but is very quiet.

[SteveMJ]

A general recap:

Stock exhaust on VXR8 does not drone; it is very quiet and subdued.
When in traffic I'm somewhat limited to the speed I can travel at. I am currently choosing to cruise on motorways at > 2000 rpm when I am able to.
Changing other major components on the car does not seem an answer to my droning.

Last but far from least is that I've known Rich24 for a long time and he has been most helpful to me (and others too). He is too busy to make exhausts for the like of me ;-( Fortnately for him he has plenty to do. We've had quiet a bit of discussion regarding 1/4 wavelength stubs (I know a little about these for electrical transmission lines) for exhausts.

I get the feeling the main culprit for the drone is the back box, but I am struggling to know what can be changed or altered to help?

Happy New Year everyone :-)

Steve

[ARAF]

SteveMJ said:

A general recap:

Stock exhaust on VXR8 does not drone; it is very quiet and subdued.
When in traffic I'm somewhat limited to the speed I can travel at. I am currently choosing to cruise on motorways at > 2000 rpm when I am able to.
Changing other major components on the car does not seem an answer to my droning.

Last but far from least is that I've known Rich24 for a long time and he has been most helpful to me (and others too). He is too busy to make exhausts for the like of me ;-( Fortnately for him he has plenty to do. We've had quiet a bit of discussion regarding 1/4 wavelength stubs (I know a little about these for electrical transmission lines) for exhausts.

I get the feeling the main culprit for the drone is the back box, but I am struggling to know what can be changed or altered to help?

Happy New Year everyone :-)

Steve

Yes, it's the aftermarket back boxes that cause it. The Wortec doesn't drone, apparently. We've taken out the cherry bombs and crossover, replacing it with a kissing pipe, yet get no drone at all - as we have original back boxes in place.

Surprisingly, having cutouts open, just in front of the back boxes doesn't drone either. I think the silencers act as the 1/4 wave suppressor.

[MyM8V8]

Don't whether this helps or is significant? I have a full Wortec (bi-modal) system on my GTS. You have the choice of quiet with plates in the back box (forcing the gasses through the silencers) which makes it quieter. With the plates removed it's straight through. Guess what?. It drones in 6th in quiet mode only! Having said that I did change the diff gears up from 3.73 to 3.46. (CV8 gearbox ratios).

[stigmundfreud]

yep, I had the bimodal on the vxr8 and when we took emily to the ring we decided to make the car quiet for the trip and put the silencer plates in = drone city

[SteveMJ]

This droning seems problematic across the board (or am I misinterpreting the postings), it seems only rarely that some do NOT have a problem.

Hmm, I'm sure I'll be asking more questions again in the New Year.

Otherwise I think I may be asking for offers and return to the stock exhaust and starting again.

Happy New Year to you all.

Steve

[stigmundfreud]

Steve one of the things to check is your exhaust is not fouling on the body or chassis somewhere.On my old ro it would drone over time as the exhaust moved on the rear rubber mount close enough to the body work to make it resonate.

Different people have different tollerences to drone also. Removing the center silences should help reduce drone - it is a pain on these engines that the gearing lends itself to being right in the middle of the motorway cruise speed

[ARAF]

Stock rear boxes are fine, but very quiet - and I'm not sure that taking out some of the baffling won't make them drone.