Bi-modal mufflers....any experiences?

[Uncle Tone]

I now have decided I hate the exhaust note of my car :(

Its BORING!!! :nutkick:

Yes, its legal, and yes, it doesn't drone, but it doesn't sound anything special when you're up it! I want more noise when I'm getting into it.

Problem is, I want to keep what I have as far as legality is concerned....

Quietness and zero drone when I'm taking it easy. So basically I want to have my cake and eat it too :lol: Also the little increase in power would be nice while I'm at it.....another aim is to get to 400rwkw on Chevs dyno legally, but thats another story :D

What changed my mind on the exhaust is going through the Burnley tunnel on the way to Chevs last Saturday......with a certain C63 beside me. Slowing down and speeding up to hear the exhaust note. The exhaust on the C63 is a work of art. No drone, legal, and LOUD when you want it to be. I want my car to go ROOOOOOARRRRRR like the C63.....at the moment it goes shhhhhhhh-choo-choo-choo-choo.....which is nice-ish, but I'd rather it go ROOOOOAAAAAARRRRRR-choo-choo-choo-choo if you know what I mean.

So we were going through the tunnel, C63 would go ROOOOOOAAARRRRR, I'd go ssshhhhhh....C63 would ROOOOOOARRRRR......I'd shhhhhhhhh.....ROOOOOAAARRRR......shhhhhhh etc etc.

Hmmmmm.....:toetap: I'm thinking the roar sounds so much better!!!

Anyway, I'm thinking a twin 3 inch system with variable mufflers....not switchable, but vacuum, electronically (or perhaps boost???) controlled. Years ago I was thinking of having a go at making some, but I can't be stuffed. So who makes these systems, other than CSV? Has anyone had any experience with these systems on cars with turbos? Mustanger had a set on his GTS and I remember that the sound level was legal on that even with his cam, and the note was nice too.....but the car wasn't boosted.

How would a vacuum operated actuator work on a turbo car? The main concern is the drone, which, when going up a hill in 6th, would become noticeable as the car would develop boost and I assume that vacuum would disappear and the mufflers would open.....right when you don't want them to, at low revs. Makes the whole excercise worthless. I'd really like to know how these systems are set up, and if they are suitable for my application.

Has anyone looked into, fitted, or otherwise had any experience with these systems on boosted cars besides CSV? I've got no problem with going and seeing Pete, but I would like a few more options if they are out there.

Also, what do we reckon is a fair expectation for a power gain? Tuna says bugger all, its a waste of money to go from a 2.5 to a 3 on my car. Would it be 10rwkw? More? Less? If its only 10rwkw for a couple of grand then yes, its a waste of money, but I really want the note.

[SSBarney]

Guess you've heard all those real sounding SS's around Melton:headbang:

I heard you driving around and thought you must have had tuner transplant a ecotec into it:stick:

In all seriousness Tone, i think its one trade off for the turbos, is you dont get that lovely V8 sound.
Instead you get people offering your car tissues when it sneezes.....

[sld86]

i had a twin 3 done by brad from mr muffler.being a turbo its still pretty quiet and would either be legal or pretty close to it. its good for just sneaking around gives the car a note (reminds you its a v8 and your one crazy mofo for putting a turbo on a v8) but doesnt attract unwanted attention. get outta town and start feeding it some throttle and everyone will know your in the neighbourhood when its doing 7000rpm. ive found it doesnt drone even leaving it in 6th going up hills etc

[Uncle Tone]

Guess you've heard all those real sounding SS's around Melton:headbang:

I heard you driving around and thought you must have had tuner transplant a ecotec into it:stick:

In all seriousness Tone, i think its one trade off for the turbos, is you dont get that lovely V8 sound.
Instead you get people offering your car tissues when it sneezes.....

Nah, haven't heard any SS's in Melton....they all stay away from me out of fear :lol:

I must admit you are right about the V8 sound and turbos. Snails are engine note killers! :bawl:

[Tre-Cool]

I'd be asking what's an acceptable cost aswell?

I think some of the valve style mufflers are pretty expensive.

Personally if you want to hear the car abit more, i'd just get someone to do you a custom exhaust, doesnt have to be expensive (depending on mufflers & shop used) I just did my brothers VE with a full 3" system for his turbo ve for less than $1K.

I figured if he is having turbo's, he's getting some Cannon's too!!! :lol:

http://www.vyssute.com/downloads/VESS/Turbo-Ve.jpg

P.S i drove to the exhaust shop. 20km's from home with no exhaust. just straight out the turbo's. they arent that loud without an exhaust.

[redvess]

Dont HM/Perry do the bi modal mufflers for the W427? maybe have a chat to them

[johnv]

I think X Force do systems with 3 stage remote controlled Varex mufflers.

here you go http://www.xforce.com.au/cars/view_car/38



A Turbo car will struggle to sound as tuff as a N/a beast for exhaust note, but the jet like spooling of turbos and BOV on a V8 still turns heads .....

[MTC]

http://www.vyssute.com/downloads/VESS/Turbo-Ve.jpg

P.S i drove to the exhaust shop. 20km's from home with no exhaust. just straight out the turbo's. they arent that loud without an exhaust.

Sorry but those look horrid:spew::spew:

[SSV8TE]

Hey tone as an intersting fact was checking out mustangers new merc. It sounds as quiet as a mouse on idle and at WOT it sounds like a supercar and full noise. The new system of exhaust has the varex type butterflies incorporated within the system. It senses when he has foot down for longer than a few seconds and opens the butterflies but on back off or light throttle the butterflies stay closed or just cracked open. All done automatically. Is fully legal and would attract no attention whatso ever from the boys in blue.
Would be interesting to research the computer controll side of this function and wether it could be a mod that we could do to our exhausts.
Just food for thought.
Cheers,

Andy.

[MaDDoG]

I read somewhere FPV are doing something along those lines also. I think John said he did something like that to his GTS before he sold it for the C63......

If you want you car to sound like Mustangers I suggest sticking spuds up his exhaust.......make it a C63 spud gun.

[HRT 8]

Hey tone as an intersting fact was checking out mustangers new merc. It sounds as quiet as a mouse on idle and at WOT it sounds like a supercar and full noise. Andy.
Andy Id agree it sounds quiet at idle but as for supercar at WOT. Obviously a very subjective opinion, but I thought it sounded absolutely terrible going up Aster Ave. last weekend, it fluffed and pepperred along (very quickly mind you) but almost soundled like it was running on 7 cylinders. In my opinion it was awfull.

[johnv]

You could use a low pressure operated hobbs switch and have it set to trigger the valves at a predetermined boost say 2 or 3 psi. or you may be able to set something up off the TPS sensor output and have it activate at a given throttle percentage.

[alexp]

Walkinshaw performance UK have a bimodal exhaust.

? may be coming here locally

try their UK website

http://www.walkinshawperformance.co.uk/wp/2008/uk/products/default.asp?content=exhaust&id=47

[redvess]

Walkinshaw performance UK have a bimodal exhaust.

? may be coming here locally

try their UK website

http://www.walkinshawperformance.co.uk/wp/2008/uk/products/default.asp?content=exhaust&id=47

as per my post before pretty sure walkinshaw use HM/Perry exhausts too

[Uncle Tone]

Hey tone as an intersting fact was checking out mustangers new merc. It sounds as quiet as a mouse on idle and at WOT it sounds like a supercar and full noise. The new system of exhaust has the varex type butterflies incorporated within the system. It senses when he has foot down for longer than a few seconds and opens the butterflies but on back off or light throttle the butterflies stay closed or just cracked open. All done automatically. Is fully legal and would attract no attention whatso ever from the boys in blue.
Would be interesting to research the computer controll side of this function and wether it could be a mod that we could do to our exhausts.
Just food for thought.
Cheers,

Andy.

Yep, the very car that inspired me to start thinking about doing this. :bow:

You get the best of both worlds from an exhaust like this. Quiet and compliant when you aren't pushing it, but then free flowing and loud when you are. Perfect! :D


Walkinshaw performance UK have a bimodal exhaust.

? may be coming here locally

try their UK website

http://www.walkinshawperformance.co.uk/wp/2008/uk/products/default.asp?content=exhaust&id=47


I think this is one that switches from loud to soft, isn't it?

I want mine to be controlled by throttle position. Also I'm after a twin 3 inch system.


Andy Id agree it sounds quiet at idle but as for supercar at WOT. Obviously a very subjective opinion, but I thought it sounded absolutely terrible going up Aster Ave. last weekend, it fluffed and pepperred along (very quickly mind you) but almost soundled like it was running on 7 cylinders. In my opinion it was awfull.

I don't think anyone will disagree with you mate....at least not to your face, anyway :errr: :lol:

[SSV8TE]

Yes tone i think it runs on time held in possition of throttle sensor not manifold pressure as with manifold pressure it would open out loud everytime you went up hills.
I think it opereates on the fact that you hold the foot in WOT for time after 3 secs or so.
As seeing it operate on the weekend it also rev limits the engine to 4000 rpm in neautral also hence the funny note when hard reving in neutral.
All in all good base and reason for research mate:goodjob:
This merc shows that it can be done and as you said would be perfect for many of us. All our modified cars are either too loud and attract attention from the boys in blue or are quiet and restrict the performance when we want it.
So hopefully we can find more info on this brilliant idea of yours tone:goodjob:

Cheers,

Andy.

[SirNemesis]

I'm interested in how this turns out. I was working on using some QuickTime Performance cut-outs to control volume from throttle position, but the problem is they take too long to open and close (3-4 seconds from closed to opened). I imagine this would be the same issue for the Varex setup, which would make signalling from the throttle a pain in the ass.

[Uncle Tone]

I'm going to see if I can drop into CSV this week and have a bit of a looksee.

[Roonstain]

Why not just get varex?
They open/close at the touch of a button - much less stuffing around IMO
My experience with them has been great - drive with mum and the grandparents in the car - quiet as a stocker
when they aren't in the car - open and full noise - sweet!
When pulled over at an RBT - closed - no probs!

The one thing i pondered was integrating the controller into the dash

[TUFFIE]

Why not just get varex?
They open/close at the touch of a button - much less stuffing around IMO
My experience with them has been great - drive with mum and the grandparents in the car - quiet as a stocker
when they aren't in the car - open and full noise - sweet!
When pulled over at an RBT - closed - no probs!

The one thing i pondered was integrating the controller into the dash

Biggest issue with the Varex is that they are not EPA compliant(legal) as they are manually controlled... they need to be controlled automatically to be Legal and EPA compliant, secondly having heard a car equiped with these from the outside it sounded like an old 253 HQ... clappy as...
my 1c worth

[iloveholden]

Biggest issue with the Varex is that they are not EPA compliant(legal) as they are manually controlled... they need to be controlled automatically to be Legal and EPA compliant, secondly having heard a car equiped with these from the outside it sounded like an old 253 HQ... clappy as...
my 1c worth

Yeah there have been a few forum members put the X-force variance mufflers on their cars only to realise they didnt like the note so off they went...back to normal resi's.

[VZMY06SS]

Don't the new XR8's run a 'semi active muffler'. It sounds like the kinda thing you are talking about.
Steve

[Uncle Tone]

Hmmmm.....:(

Went to see Pete at CSV this week and the system sounds like a winner.....for everybody else!! :bawl:

There is no guarantee that lugging up a hill in 6th gear won't open the mufflers up. As boost builds vacuum decreases, and the valves open....and at 1600rpm on a VE thats the last thing that you want happening with a lout 3 inch system!

So I don't think that this is the system for me. I need a turbo-friendly Bi-Modal system.

I still love the concept, though.

[mustanger]

You`re a tight arse Tone, you just don`t want to spend the moola :).



(Maybe no funds have been approved)

[Party Pete]

If it operates on vacuum pressure, could it's sensitivity to this not be modified so as to work with a turbo car?

The Ford system used on the XR8 is similar to the one used on Jaguars and I believe it works on a fairly simple principle of spring tensioned bypass valves opening as exhaust gas pressure increases. Sounds like a simple and reasonable idea. Does anyone know how the Walkinshaw system in the UK works, ie, vacuum, spring, ECU or manual switched?

[SICK SS]

I now have decided I hate the exhaust note of my car :(

Its BORING!!! :nutkick:

Yes, its legal, and yes, it doesn't drone, but it doesn't sound anything special when you're up it! I want more noise when I'm getting into it.

Problem is, I want to keep what I have as far as legality is concerned....

Quietness and zero drone when I'm taking it easy. So basically I want to have my cake and eat it too :lol: Also the little increase in power would be nice while I'm at it.....another aim is to get to 400rwkw on Chevs dyno legally, but thats another story :D

What changed my mind on the exhaust is going through the Burnley tunnel on the way to Chevs last Saturday......with a certain C63 beside me. Slowing down and speeding up to hear the exhaust note. The exhaust on the C63 is a work of art. No drone, legal, and LOUD when you want it to be. I want my car to go ROOOOOOARRRRRR like the C63.....at the moment it goes shhhhhhhh-choo-choo-choo-choo.....which is nice-ish, but I'd rather it go ROOOOOAAAAAARRRRRR-choo-choo-choo-choo if you know what I mean.

So we were going through the tunnel, C63 would go ROOOOOOAAARRRRR, I'd go ssshhhhhh....C63 would ROOOOOOARRRRR......I'd shhhhhhhhh.....ROOOOOAAARRRR......shhhhhhh etc etc.

Hmmmmm.....:toetap: I'm thinking the roar sounds so much better!!!

Anyway, I'm thinking a twin 3 inch system with variable mufflers....not switchable, but vacuum, electronically (or perhaps boost???) controlled. Years ago I was thinking of having a go at making some, but I can't be stuffed. So who makes these systems, other than CSV? Has anyone had any experience with these systems on cars with turbos? Mustanger had a set on his GTS and I remember that the sound level was legal on that even with his cam, and the note was nice too.....but the car wasn't boosted.

How would a vacuum operated actuator work on a turbo car? The main concern is the drone, which, when going up a hill in 6th, would become noticeable as the car would develop boost and I assume that vacuum would disappear and the mufflers would open.....right when you don't want them to, at low revs. Makes the whole excercise worthless. I'd really like to know how these systems are set up, and if they are suitable for my application.

Has anyone looked into, fitted, or otherwise had any experience with these systems on boosted cars besides CSV? I've got no problem with going and seeing Pete, but I would like a few more options if they are out there.

Also, what do we reckon is a fair expectation for a power gain? Tuna says bugger all, its a waste of money to go from a 2.5 to a 3 on my car. Would it be 10rwkw? More? Less? If its only 10rwkw for a couple of grand then yes, its a waste of money, but I really want the note.
supercharge it if you want it to sound like a tuff v8

[lee ls1]

Have a look at my cutout thread, (was only a bit of fun built in the shed)

http://www.ls1.com.au/forum/showthread.php?t=104210&highlight=cutouts

[Uncle Tone]

supercharge it if you want it to sound like a tuff v8

I agree there, but I don't want to cut the power output in half mate :stick:

[EXCESSV]

but what about the ADR/Emission compliance that u wanted so much?
it surely will be torn up with an exhaust mod :stick:

[surfwagon]

I thought I read somewhere that the Bi-moda mufflers on the HSV W427 were vacuum operated which would have them opening on most hills if in a high gear.
But maybe they are vacuum but also electronic so they only open when you are really up it.

[Uncle Tone]

but what about the ADR/Emission compliance that u wanted so much?
it surely will be torn up with an exhaust mod :stick:


Nope :D :nutkick:

[mustanger]

I think this is what UT is trying to acheive.Quiet on idle and at cruising speed but with a nice note at WOT. This is a standard AMG system .

YouTube - Mercedes c63 amg exhaust- Amazing, MUST HEAR! (http://www.youtube.com/watch?v=UFtTLfXaC6U&feature=related)

[bwhinnen]

Tone, for a FI car it would simply be a matter of picking up something that can do it based on RPM and TPS. This way you can have the valves open when you reach a certain RPM and have TPS above a set amount.

The design and programming wouldn't be rocket science, TPS is simply just a voltage however there will need to be a few converters / circuits as the engine speed output is usually a waveform, but this shouldn't be too difficult.

Apparently the C6 corvette has an option called NPP (dual mode exhaust system), this is controlled by the ECU and works on engine RPM and the output from the TPS. Might be worth looking into further. I wonder if the LS9 equipped model has something similar, being FI from factory...

I think the hardest part will be finding a muffler that sounds decent in both open and closed modes rather than the logistics of actually controlling the opening and closing of the valves!

Brett

[ADAM 26]

walkinshaw are bringing them out in aus very soon!

they are operated the computer with , revs, load, speed, and throttle possition.

also 100% legal!

[Uncle Tone]

Tone, for a FI car it would simply be a matter of picking up something that can do it based on RPM and TPS. This way you can have the valves open when you reach a certain RPM and have TPS above a set amount.

The design and programming wouldn't be rocket science, TPS is simply just a voltage however there will need to be a few converters / circuits as the engine speed output is usually a waveform, but this shouldn't be too difficult.

Apparently the C6 corvette has an option called NPP (dual mode exhaust system), this is controlled by the ECU and works on engine RPM and the output from the TPS. Might be worth looking into further. I wonder if the LS9 equipped model has something similar, being FI from factory...

I think the hardest part will be finding a muffler that sounds decent in both open and closed modes rather than the logistics of actually controlling the opening and closing of the valves!

Brett

The biggest problem is drone under 2000rpm. What I was thinking of doing is having a solenoid controlled by the ECU letting vacuum through (opening) only above 2000 rpm or so, and being closed under 2000rpm. So even if boost builds up hills the solenoid won't let any vacuum through and won't open the mufflers. This will eliminate my problems, but even this is a stop gap measure. If you go over 2000rpm with some boost built up the solenoid will snap open and exhaust will be louder in an instant, like the Xforce switchable ones. Not really what I'm trying to achieve.


The CSV exhaust is one of the best I've heard on a NA VE.....Turbo VE's are a completely different animal, however. No matter what you do, its hard to get a turbo car to sound really good.

Hmmm.....


I wonder if its possible to get the actuators to work in reverse? Just open when there is boost? After all, boost is just vacuum in reverse, isn't it? I wonder if that would work......


walkinshaw are bringing them out in aus very soon!

they are operated the computer with , revs, load, speed, and throttle possition.

also 100% legal!

That would probably be the best way to do it I guess, however very complex I'm guessing.

And expensive I'd wager, being from Walkinshaw.

[smokiebbear]

UT I have two words for you .... Baby Cam.

Will make it louder and should net you an extra 20rwkw. And if the cam is small enough nobody will ever know it's there.

[Uncle Tone]

UT I have two words for you .... Baby Cam.

Will make it louder and should net you an extra 20rwkw. And if the cam is small enough nobody will ever know it's there.

Nah mate, not for a boosted engine. Cams don't do diddly-squat for turbo cars. :(

[vyssbeast]

I think a remote operated one, KISS (keep it simple .... )

When you want it loud press the button
When you want it quiet ... press the button

Anything automated that is set to open and close at certain points is bound to piss you off ... imagine you need to do a subtle overtake, nothing psycho, just gettin round someone and due to slipping over 2k or alittle boost build up you get this SUDDEN increase in volume and unwanted attention (sounds like you floored it)

So have it button operated, quiet no matter what happens, unless you wanna drive round with abit off noise on a nice sunny day with the windows down...

Just my opinion

[bwhinnen]

Nah mate, not for a boosted engine. Cams don't do diddly-squat for turbo cars. :(

Actually they do and can... (cams that is on turbo cars, comes down to cost versus gains)

Back to the control of the bi modal, depending on how much you want to invest in the control system it could be very easily tailored to how you want it, even switchable on when it automatically changes. I.e flick of a switch it will automatically come on over 4000rpm and 60% throttle (i.e. subtle mode) or over 2000 and 40% throttle (you should be making a significant amount of boost by then anyway) for look at me mode. Of course you could easily have it work on the MAP signal anyway, that is just a voltage anyway and quite simple to program...

[4digit]

With the Turbos you can have your cake and eat it! The answer is not your exhaust, you need a set of external gates vented to atmosphere. Result = quite around town, highway, cruise and sounds like a top fuel dragster when your up it.

[exwrx]

Screamer pipe?

[PESSV]

On the Perry I just put on the inner pipe does all the work at idle, the outer does very little as mentioned before. Looking into the muffler, all you see on the outer pipe is a baffle about half way in and there is a small (25mm?) balance pipe across to the inner pipe. That’s it. Doesn't seem to be anything that can be vacuum operated. On the W427 the rear mufflers are described as 'active bi-modal', with vacuum-operated valves to re-route high-speed gasses to better manage gas flow. On mine there appears to be nothing, I can't see any sign of valves etc but that doesn't mean they aren't there. If you block the inner pipe off, bugger all still comes out the outer so I doubt they are the same muffler. I think they would let us know if they were. They are a different design though and there must be some science in this sort of dummy chamber and balance pipe.

With the headers and cats, the note is nice. Reasonably quiet at idle and down low but reasonably loud on revs. Mostly due to the headers and cats more than the mufflers I suspect.

So if you want to control the noise levels, the W427 mufflers wouldn't be the answer because they are vacuum controlled. As far as electrically controlled etc, just humour me here. Turning down the volume using Exhaust Control Valves also restricts exhaust flow. We put flash exhausts on to reduce back pressure and increase flow out of the engine to reduce pumping losses. Pumping losses are the amount of horsepower used (lost) to push exhaust gases out of the cylinders on the engine's exhaust stroke. So when you shut the ECV’s, back pressure increases, flow rate decreases, less HP. This in turn will reduce the incoming airflow, the ECM probably picks up these different flow rates and makes minor changes to suit. This could happen every time you open and close them. What they cost in reduced flow and power may also be bugger all, I don’t know. I’m just imagining putting your boot into it expecting one thing and being disappointed when something less happened because the ECV’s were shut. Can you feel any difference?

[spinr33]

I dont understand why you dont just put twin 3.5" exhaust on and put only as many mufflers as u need to have 90db and be done with it best flow versus best setup you can legally have.
I had a 3.5" on my skyline 1 straight thru muffler and thats it and it only registerd 95db on police db meter after all the police crowded around thinking it was going to be ridiculesy loud so really you dont need much to keep a turbo quiet, but the back off db where like 96db and had a pain in the arse trying to shut the back off db for the noise test argh, managed to pass this also with restriction plates and same system, do yourself a favour mate and just keep it at legal db its not worth the effort of having something overly loud.
my 2 cents Rory

[butterfly effec]

Check out Autospeed using pure pipe perfection 2 , pure pipe perfection 3 and butterfly effect as a search and you will see an exhaust modification that is now marketed by hyperflow technologies and is on their web-site as active exhaust system. I initiated the concept and still involved with hyperflow. I recently updated my lj torana , chev powered with a dual 3" active exhaust and it will be tuned next week. This system works and can be fitted to high flow systems to give them a quieter, lower performance system when desired. No drones and quieter usually triggered at 100% tps to full flow, returns automatically to quiet, back-pressure regulated mode after time delay period. Problem solved.