Bi-modal Exhausts

[Caseyj]

Not sure where to post this but I'm looking for feedback or interest on a bi-modal exhaust set up that I will be selling in the near future. For those unsure of what a bimodal exhaust is; it is an exhaust system as fitted to top model cars such as Ferrari, Lamborghini, Aston Martin etc. The system is of all stainless steel construction and unlike other systems it is fully variable from closed (mild normal sound) to fully open (full performance-loud) and is operated at the push of a button, so you can tune the sound to your preference. It will be available to a number of specific car systems so straight bolt on replacement, or universal fit for those one off situations or simply for those who want to mod their ride.

Please reply to indicate interest at this stage as I would like feedback to judge the next phase of the project


Caseyj

[ManOpener]

I'm not a supercar owner so disregard my opinion if you want, but aren't bimodal exhausts a little bit pointless? IMHO, if you are in the market for a proper supercar but want the function to "turn it down a bit" you might as well not buy one. The whole exhaust switching thing is a silly gimick- much better to have a properly set up, lighter exhaust system (if you can get 1000bhp unlimited-series Time Attack cars below 100db, you should be able to do it for your average Ferrari or Aston) than a heavy one full of valves that let you make it louder or quieter.

All personal opinion of course.

[Flying machine]

I don't have a 'supercar', but have to say that the switchable exhaust on the 911 is a good idea. When on the motorway and you want a quieter drive and less drone - push of a button. Get on to some good roads, push of a button and enjoy the engine note. I suspect that there should be a good market for these if you've got a nice engine note hidden away somewhere....

Best of both worlds, good luck!

[TheEnd]

BMW have been doing something similar for years, where there is 2 paths through the silencer, one for town driving, and another one that opens up over a certain road speed and throttle position.

I'm pretty sure Aston Martin factory fit an exhaust like that on some of their models too.

[ben10]

TheEnd said:

BMW have been doing something similar for years, where there is 2 paths through the silencer, one for town driving, and another one that opens up over a certain road speed and throttle position.

I'm pretty sure Aston Martin factory fit an exhaust like that on some of their models too.

Aston martin do, I know the person who made the exhausts for AM, the reason they did it was for the various crappy laws not for "a quieter noise" - It's a supercar, they are supposed to be loud.

[zakelwe]

"and unlike other systems it is fully variable from closed (mild normal sound) to fully open (full performance-loud) and is operated at the push of a button"

But isn't that what Porche etc have been doing for years now?

Andy

[TheEnd]

ben10 said:

it was for the various crappy laws not for "a quieter noise" -

Was that a misquote?
The crappy laws would have been noise restrictions.

[maniac0796]

TheEnd said:

BMW have been doing something similar for years, where there is 2 paths through the silencer, one for town driving, and another one that opens up over a certain road speed and throttle position.

I'm pretty sure Aston Martin factory fit an exhaust like that on some of their models too.

Think the BMW ones are vacuum operated though. Correct me if wrong.

[TheEnd]

maniac0796 said:

TheEnd said:

BMW have been doing something similar for years, where there is 2 paths through the silencer, one for town driving, and another one that opens up over a certain road speed and throttle position.

I'm pretty sure Aston Martin factory fit an exhaust like that on some of their models too.

Think the BMW ones are vacuum operated though. Correct me if wrong.

Vacuum supplies the motive power, but it's an ECU controlled solenoid that decides whether the flap is open or closed.

[ben10]

TheEnd said:

ben10 said:

it was for the various crappy laws not for "a quieter noise" -

Was that a misquote?
The crappy laws would have been noise restrictions.

No, more of a mis-communication, perhaps I didn't explain it very well, I will try again.

They had to make it quieter to comply with the laws, not because customers wanted their new V8/V12 to be quieter.

ETA: maybe too many comma's, English wasn't my strong point but I try

Edited by ben10 on Wednesday 20th October 21:26

[TheEnd]

ben10 said:

TheEnd said:

ben10 said:

it was for the various crappy laws not for "a quieter noise" -

Was that a misquote?
The crappy laws would have been noise restrictions.

No, more of a mis-communication, perhaps I didn't explain it very well, I will try again.

They had to make it quieter to comply with the laws, not because customers wanted their new V8/V12 to be quieter.

ETA: maybe too many comma's, English wasn't my strong point but I try

Edited by ben10 on Wednesday 20th October 21:26

Thought as much, I know in BMWs case, it was for quietness and refinement, but on the bigger cars, it's due to some combined drive by noise limits, which include all noises, like tyre noise, so they need to keep things hushed to sneak through.

[LuS1fer]

Electric cutouts are proving popular for American muscle cars so a bi-modal system at the right price might be of interest.

[snuffle]

Fuse 22. if that helps at all

[Jonny_693]

The trouble with these is when they are standard fit the engine management is designed to interact with the valve. How do you propose to get an aftermarket one to interact with the cars ecu? When the valve opens you're going to get a lot less back pressure which is surely going to play havoc with the cars mapping?

[ben10]

Jonny_693 said:

The trouble with these is when they are standard fit the engine management is designed to interact with the valve. How do you propose to get an aftermarket one to interact with the cars ecu? When the valve opens you're going to get a lot less back pressure which is surely going to play havoc with the cars mapping?and power figures

Agreed, without the millions to spend on R&D you are most likely going to fk up the various pressures in the system.

The company that produced the AM exhausts used a piece of software that showed them the exact air flow and pressures through the whole system. Not cheap but if you are playing with such things you are most likely going to have to fork out on such programmes or risk buggering up the balance that was so carefully manufactured into the system in the first place.

Edited by ben10 on Wednesday 20th October 21:54

[V88Dicky]

I think the VXR8 Bathurst and Bathhurst 'S' came with a bi-modal exhaust, courtesy of Walkinshaw. Push button on dash to operate.

The difference in back pressure between a straight through piece of exhaust and a properly set up, low restriction silencer is neglible anyway and certainly doesn't effect the mapping on the HSVs and Holdens that I've seen these systems on.

Even cutouts placed in the optimum position seem to be fine and don't throw any ecu errors on the dash.

[mattmoxon]

You won't mess up the back pressures on a car with cat's as they provide the back pressure for many systems, it's an interesting idea fitted to the back box section of the exhaust it really wouldn't do any harm.

I know of several cut out systems (mechanical and electrical) that are popular in the American car scene they fit to the exhaust straight after the cats and bypass the whole system aft of it when open. As far as I know these don't affect the engine running at all.

It wouldn't be that hard to make it interface with the ECU, certainly no harder than a shift light, i.e. open the exhaust at a pre-set RPM and have an override button to make it loud all the time.

[Caseyj]

Thanks for your comments, these exhaust are designed to be comparable to a "sports" exhaust, they are stainless steel of high quality construction with variable flow paths internally and available for the HSV Monaro VXR8, Subaru Impreza, Skyline and many others. They do not alter or mess up the engine mapping, they do allow for a more free flowing exit of exhaust gasses after the cat and can give power gains where the original exhaust is restrictive, this is the main reason top manufacturers choose bimodal setups and of course to create a deep burble of an exhaust note. Most bimodal exhausts operate on either vacuum valve or rev dependant electronic control, being either open or closed. This system is different in that it allows the valve to be stopped at any position, so giving the option to tune the sound. Porsche, BMW, AM, Corvette and others have been doing this for some time, now it's available to all.

[Aeroresh]

Ive got one on my VXR8 Bathurst S.

Its ok but it just turns the exhaust volume from "loud" to "louder" and it doesnt sound much different from in the cabin.

Other than trying it out and experimenting when I first got the car, mine has been set permanently to "louder" ever since!

[bertelli_1]

Pleae tell me you are going to use a vacuum system not an electric valve. The electric ones sieze all the time - they will be a warranty nightmare.