Active Exhaust / Bypass Valve

[DonkeyApple]

Don't firms like Miltek build the bypass into a silencer box? These are then operated by pressure or a switch.

Surely one of these firms can build their kit into a TVR box thus eliminating the external bypass onto a separate system/vent. That seems a clumsy solution.

[MPoxon]

DonkeyApple said:

Don't firms like Miltek build the bypass into a silencer box? These are then operated by pressure or a switch.

Surely one of these firms can build their kit into a TVR box thus eliminating the external bypass onto a separate system/vent. That seems a clumsy solution.

I agree this would be a much better option. I couldn't find anything on the Milteak site, the only company I have found who make silencers with a build in bypass are a company called Varex. Varex sell back boxes with a electronically controlled butterfly valve which allows either straight through or silenced:



Looks really good:
http://youtu.be/K7jGYnhbQQU?t=29s

The only problem is that their centre box would not suit a TVR as one side is blocked with the valve is closed.



Providing it is loud enough when fully open a system like this would be my preference as it promises to give the best of both worlds at the flick of a switch without the need for an external valve, however I have not had any luck finding a product that is fit for purpose.

[EGB]

http://www.youtube.com/watch?v=ahct5yzUtdE
For you boyos who like a good noise. Try this one with dopler effect. For your horn or alarm. Max the volume on PC. My son (electronic engineer) co driver of a Griff also works for BHP Bileton Iron Ore trains in oz and will take orders for a horn !!!!!!!!!!!!!Murth!!!

Edited by EGB on Saturday 12th November 22:54

[gavgavgav]

EGB said:

http://www.youtube.com/watch?v=ahct5yzUtdE
For you boyos who like a good noise. Try this one with dopler effect. For your horn or alarm. Max the volume on PC. My son (electronic engineer) co driver of a Griff also works for BHP Billeton and will take the orders !!!!!!!!!!!!!

?

[The Moosehunter]

clive f said:

moosehunter did this a few years ago, he fitted the valve into the pipework just alongside the sump.........deafeningly sodding loud!

Hi Guys

Sadly I was expecting great things and have ended up with a car that appears to have lost some of the magical qualities of a V8 and inherited some Massey Fergusson

It sound better if you block the rear tailpipes as some of the exhaust gases still go down the original route. Though driving down the road with the sole of each shoe against the tailpipes is not very practical

I would definately persue the switchable silencer route as this would definalty give a better note 9 it's not all about the volume for me

You are welcome to hear what it sounds like once I have found some pistons that stop destroying themselves in my car

5 months without and getting pretty peeeved

Summary is it's a good comedy moment but for sustained "quality" volume it sucks ( or blows )

Spend a liitle more time / money and switchable silencer it ( then tell me where you got it )

Good luck

Andy

That said it you wish to borrow my complete system to try it out then you are welcome as it's currently in my shed and hanging from the roof of my garage. I'll swap you for a drive in yours, I can be trusted .... honest

[DonkeyApple]

I suspect that there could be quite a few TVR owners out there who would buy a 'Town & Country' box if it were available. It could even be cost effective if many of the models could fit the same unit. I would assume that Griffs and Chimps do but if the same middle box could fit nearly all Tivs then one of the TVR parts suppliers may be interested in reselling a bespoke Miltek (or similar) system?

I wonder if the simplest possible system would be a perforated sleeve within the perforated sleeve of the exhaust that can be slid half an inch to either align the perforations or block them? A solenoid system on the outside could then work the slide?

[Chimpabollics]

Love the solenoid activated sliding sleeve idea.

But could this be a simpler cheaper solution?

http://www.dynomax.com/mufflers.php?muffler=vt

[pjac67]

MPoxon said:

pjac67 said:

I have looked into this before on my Wedge and the heat/potential and possible fluid getting onto the tyres put me off - I just removed most of the box (122 db) which I know isn't your goal but was also a fractin of the cost.

On my Griff however, the ECU has different settings at the flick of a switch so can go from quiet to 'pops and bangs' mode although as it is just changing the fuel mixture/set up it is not massively louder....

I agree the heat, fumes, fluid and flames underneath the car are a concern which is why I am looking at either Derek's idea of the side exit pipe or possibly some way of getting an additional pipe to routed towards the rear of the car.

Are you achieving the pops and bangs using an aftermarket ECU (Omex???) or are you still using 14CUX. I know you can provoke pops and bangs by adjusting the amount of fuel that is injected on the over run or if you have mapped spark then retarding the ignition on overrun = fireworks May I ask how you have yours setup.

Hi - Emerald ECU (not sure about mapped spark) - updated my profile if that helps. Went out for a run with a fellow Griff owner (think it was an old airstrip...) at w/e and had flames exiting exhausts (always wanted to do that ) when changing up to 5th at 5500 rpm ....

BTW, decided mine is too quiet (fully decatted/ Clive's Y fronts and ACT pre cat manifolds) s considering cherry bomb/motorbike exhaust route....

[MPoxon]

The Moosehunter said:

Hi Guys

Sadly I was expecting great things and have ended up with a car that appears to have lost some of the magical qualities of a V8 and inherited some Massey Fergusson

It sound better if you block the rear tailpipes as some of the exhaust gases still go down the original route. Though driving down the road with the sole of each shoe against the tailpipes is not very practical

I would definately persue the switchable silencer route as this would definalty give a better note 9 it's not all about the volume for me

You are welcome to hear what it sounds like once I have found some pistons that stop destroying themselves in my car

5 months without and getting pretty peeeved

Summary is it's a good comedy moment but for sustained "quality" volume it sucks ( or blows )

Spend a liitle more time / money and switchable silencer it ( then tell me where you got it )

Good luck

Andy

That said it you wish to borrow my complete system to try it out then you are welcome as it's currently in my shed and hanging from the roof of my garage. I'll swap you for a drive in yours, I can be trusted .... honest

I am really sorry to hear that you have still not got your car sorted yet

Thanks for the information on the bypass I had a sneeking suspicious that that may the case, hence why I was looking as possibly routing the bypass through a sleved silencer of some sorts although I am really not convinced it is practical.

I think I will take you advice and persue the switchable silencer route.

Matthew

[MPoxon]

DonkeyApple said:

I suspect that there could be quite a few TVR owners out there who would buy a 'Town & Country' box if it were available. It could even be cost effective if many of the models could fit the same unit. I would assume that Griffs and Chimps do but if the same middle box could fit nearly all Tivs then one of the TVR parts suppliers may be interested in reselling a bespoke Miltek (or similar) system?

I wonder if the simplest possible system would be a perforated sleeve within the perforated sleeve of the exhaust that can be slid half an inch to either align the perforations or block them? A solenoid system on the outside could then work the slide?

I agree I think there is definitely a market for this. The if there is a switchable middle box that fits the Griff then like you say this will also fit the Chim.

I system that changed the current style silencer from perforated to non would be ideal. The best sound for a Griff IMO is all cats out, sleeved with wadding left in which that system would achieve. Sleeved without wadding sounds a bit to agricultural IMO.

[MPoxon]

Chimpabollics said:

Love the solenoid activated sliding sleeve idea.

But could this be a simpler cheaper solution?

http://www.dynomax.com/mufflers.php?muffler=vt

I am not convinced this would be any louder as it still has a section of perforated pipe even when the valve is open:



They do not appear to have a dual inlet dual outlet version either.

I will have a chat with Tim at ACT next time I speak to him see if it is something he has looked into before.

[MPoxon]

pjac67 said:

Hi - Emerald ECU (not sure about mapped spark) - updated my profile if that helps. Went out for a run with a fellow Griff owner (think it was an old airstrip...) at w/e and had flames exiting exhausts (always wanted to do that ) when changing up to 5th at 5500 rpm ....

BTW, decided mine is too quiet (fully decatted/ Clive's Y fronts and ACT pre cat manifolds) s considering cherry bomb/motorbike exhaust route....

Holly st the spec of your Griff is immense. That is pretty much the exact spec I would like to have but will take me 20 years to save up and and achieve. IMO some people go a bit too far with modding but that is spot on

It says on your profile you have coil packs so Emerald will be controlling the spark..... you could have it mapped into one of your switchable maps to chuck flames out all the time on the over-run if you wanted.

If you want louder I wouldn't necessarily recommend the ACT Cherries, they sound epic and like I said earlier in the thread they are IMO the best compromise but I think you may be disappointed if you buy them to increase volume. Sleved OEM box with wadding left in is a good shout and is about as loud as you can go without the tractor sound. Gizzers bike silencers are also a good shout - very loud indeed.

[pjac67]

Having looked at your profile Matthew (Matt?) I don't think you have anything to worry about with your spec. - and look at that engine bay - Wow!

Can't wait for next years GG (not been for a few years...) to see/hear all the cars although I do like the bike exhaust idea (a la 'Gizzer'..).

Paul.

[MPoxon]

pjac67 said:

Having looked at your profile Matthew (Matt?) I don't think you have anything to worry about with your spec. - and look at that engine bay - Wow!

Can't wait for next years GG (not been for a few years...) to see/hear all the cars although I do like the bike exhaust idea (a la 'Gizzer'..).

Paul.

Thanks Paul, definitely come along to the Growl next year, it would be great to catch up and get a proper look at the Griff. I know FFG has a few plans for a 30th Anniversary special.

I am hoping that Gizzer comes to his senses and decides to keep his Griff, it certainly wont be the same without the loudest car and loudest owner present

[hugerr]

This is something I'm looking in to now. I have a Chim with the mid box sleeved and the noise is fabulous, but very loud. Great for short runs, but an be oppressive on long motorway runs and definitely upsets the neighbours on late night returns, plus it's too loud for most track days, even with extra tail-pipe silencers.

I'd be very happy to invest in a system with a switchable valve offering the options of (relatively) quiet and refined or utter hooligan modes.

The Y-pipe thing might be do-able but I'm not sure about the practicality of running dual pipes to the tail pipes. An all-in one solution in the centre box would be a better option, but I can't find anything suitable right now.

I'm sure there'd be a lot of interest in a well designed bespoke system for Chims and Griffs...

Hugh

[DonkeyApple]

Milltek seem to make valved back boxes for so many types of car, I still think that if someone calls them with the basic dimentions of the Griff box they may well haveone for another car that will fit.

I can't imagine that TVR built their exhaust sytems bespoke but used existing pipe dimentions and boxes.

[pjac67]

Thought I'd resurrect this before thje Growl - has anyone managed to fit a bypass/butterfly valve? Still on my agenda .....

[pjac67]

Just thought I'd resurrect this as I am finally investing the time and money into developing a switchable (electronic) 'butterfly' valve with side exit exhaust.

If successful I will post an update/video clip when complete for anyone who is interested.

[MPoxon]

I would be very interested to see what you come up with Paul. Ideally I need to make mine quieter for track use but I would love the ability to be noisy at the flick of a switch.

[Podie]

Also keeping an eye on progress