After much research I have swapped an Amuse Dual for an Invidia. The goal being, to make more noise. Goal accomplished, big-time All below refers to the invidia without its silencers, which I have not fitted since going down in DB's is not a part of my plan.

There has been much written about the Invidia. My opinion is a very loud and well-built exhaust system which sounds not unlike half a Ferrari 348 engine with a Tubi aftermarket exhaust. The VTEC noise from the Invidia is certainly Ferrari-esque. All of which is good.

Enter the dreaded Booming. Between approximately 3-4000 RPM the system (and the car and everything around it) is taken over with bass so loud it literally deafens you for an hour after stepping out of the car. Apparently it's also bad for your health.

Only a particular rev range is affected. Below 3,000 in particular there is no Booming.

Now on the standard exhaust and also on the Amuse, one could sense the same drone although quieter and barely noticeable. Both of those systems use twin resonators being a Helmholtz pipe, and a box resonator/silencer (anyone know what's inside that central box?). The resonance frequency then seems to be a characteristic of the rest of the s2000 and the system layout rather than a particular tuning of a particular exhaust. The exhaust design either amplifies it or does not do so. The drone is already 'in' the car design.

I note some comments re. inserting the whole after-cat pipe from the stock exhaust including both resonators. I don't want to do that because I want to keep the sound of the Invidia similar and also the DB level. I fear the stock resonator box will quieten the system and radically change its sound which is not the point. The booming is not so much audible outside the car. All we need to do is remove the booming and leave whatever was there before, well alone.

I think the solution is probably the attachment of a Helmholtz resonator. This can be done cheaply however some forethought and discussion are appropriate beforehand since this seems to be unchartered territory and this Droning is a hot issue with S2000 exhausts.

In theory at least the Helmholtz pipe acts as a damper at certain frequencies, in audio terms this is called an attenuating notch filter. It cuts out certain sound waves at a particular frequency and, spreads out its effect either side of that frequency, without affecting the rest of the frequencies in the sound. In theory a Helmholtz pipe should precisely cancel-out the drone and solve the issue.

Both the stock exhaust and the dual Amuse use a Helmholtz pipe in roughly the same position and size.

In theory, if the same is added to the Invidia, it should cancel-out some of the drone.

Has anyone ever tried adding/removing a Helmholtz resonator to any S2000 exhaust (or any exhaust), and what was the result?

Any input appreciated before I take the plunge and draw the plan for the welding shop.

Rgds
TLE

 

damn u swapped an amuse for an invidia? I kno u wanted to make more sound but damn! haha...

anyway, im not sure about adding that particular resonator, but id guessing it would change the note through-out the rpm range...be interesting to see how it comes out. If ur near california id be happy to weld it up for ya...tig certified

 

I thought about doing this too along with using the stock regular resonator but I can't justify hacking up a nicely made exhaust for something that "might work."

 

So are you saying you have an Amuse for sale?

 

It's early days to decide yet

The Amuse went quieter in the first few months of use. I might leave the invidia a while just to see if it quietens down inside the car of its own ageing process.

Agree it seems a big step to butcher an exhaust but it's only a bit of steel piping and if it fails it can be reverted. The welds on the invidia are good quality but hardly artwork.

 

wouldnt you want an exhaust thats a little more free-flowing than an amuse? like say a custom 3" stainless exhaust, mated to a Veilside teardrop muffler? that would sound nice on a SC s2000, imo.
-Chris

 

Wow this whole thread just confuses me...

First why would you swap these exhausts? What you are saying is that you want a heavier exhaust just because it's louder...? Just change to a single outlet, save the weight and enjoy beating the hell out of your ears.

As for modifying the exhaust. You are not only adding weight to your car but now your talking about changing the characteristics to an unknown system which may not show any gains but yet still... it's louder. Oh wait not too loud, thats why you want to modify the Invidia.

As for adding the resonator to the exhaust, in some respects the resonant chamber gives the end result of a notch filter but what your actually doing is bleeding off the frequencies which would be subject to the placement of the branch pipe.

The location, diameter and depth of this pipe are all dependant upon the wavelength of the frequencies you are trying to attenuate. You cant really just slap an extra pipe on the exhaust and hope it works. Although this isnt saying that, it wont work.

I just cant imagine why you would do this. It's alot of work that could be better approached with a single outlet exhaust. If you want your car to be that obnoxiously loud, no one is going to care if you have one or two exhaust tips.

 

Both exhausts are dual. I don't think there would be much weight saving with either in a single version since they are both fairly light anyway. A few lbs at most.

Gains also was not an issue, a few BHP either gained or lost on this car, IMHO isn't noticeable anyway. Donning flame suit for that but true.

The invidia is loud and produces the sound I wanted it to produce, mostly. It's a lot nearer than anything else I have heard. Hence i fitted it. What I'm talking about now is maybe customizing it, a little.

Thanx for the info re the branch pipe effects. I was thinking of simply mirroring the stock pipe placement. Weight is not a factor, adding maybe half a lb.

I don't see any advantage to switching to a single outlet in this case. There doesn't seem to be a reason to do so. Or in other words I don't see any particular disadvantage with the dual setup. Single-vs-dual is for me a matter of appearance and not much more than that.

On subject of obnoxious noise, the invidia has plenty of that anyway. It's a beast of a system.

 

Clarification: This is about making a hell of a noise without going deaf. The invidia provides the first throughout the rev range but the second only between approximately 3-4k revs. If I can dial-out some resonance in that range I will achieve both goals.

The point I find interesting is that the stock exhaust comes with the Helmholtz resonator which Amuse copied. It seems to me though an experiment will be necessary to bear this out, that the design to kill the mid-range drone is already finished and in production in that standard helmholtz pipe on the stock exhaust.

Certainly that pipe is tuned to a frequency and reduces resonance in that frequency, it seems logical that it targets the mid-range where all s2ks tend to have 'some' drone albeit how small, and since the pipe lengths are similar, one might expect the mod to be a worthwhile exercise.

 

Is the Helmholtz pipe the little stubby dead-end pipe on the stock exhaust?