Fiesta ST - gaining boost from Mountune's Symposer Delete kit

[MarkCup]

Surprising results...the only symptom was a lack of cabin sound from the symposer, results were that boost was being lost across wide rev range.

 

[Gally]

Can you explain further Mark?

 

[Mr Plums]

Can you explain further Mark?

Did you watch the video?

It cant get much more detailed.

 

[MarkCup]

Can you explain further Mark?

The sound symposer is little more than an enclosed plastic box with a plastic and rubber diaphragm sandwiched between two halves and some torx screws to secure it. It is fully enclosed on the intake side (and it resonates on the cabin side to generate the sound), but under boost it seems some can leak beyond the rubber seal of the diaphragm.

My symposer had stopped making noise, it has been like it for a while, but I though nothing of it as the car still felt the same. The recent Surry Rolling Road day showed I was a good 10bhp off where I should have been...and my boost clamps all needed a little pinch up...then I got thinking about the symposer.

I've heard that they're a weak point but no one has ever said exactly why or how they fail. I bought the Mountune delete kit as I though seeing as mine was making no noise at all something must be wrong with it.

As it turns out I was right.

 

[Sam]

So does this Sound Symposer just add noise in the cabin for your pleasure ? Like putting a coke can on your bikes back wheel ?

 

[MarkCup]

So does this Sound Symposer just add noise in the cabin for your pleasure ? Like putting a coke can on your bikes back wheel ?

Yes, well, sort of...

Imagine a box which is divided into two halves with the wall separating them being a rubber membrane.

One half of the box is connected by a pipe to the intlet tract right next to the throttle body, the other half connects to another pipe that routes into the passenger footwell.

Energy pulses back from the throttle body make the membrane vibrate causing sound to go from the other non pressurised side of the box into the cabin.

So, in theory at least, it is actual induction noise...

 

[McGherkin]

Loads of people delete this on the Mk2 Focus ST, for this reason.

 

[mr bognor]

I like the noise on my one I think it makes the car and a good little bark in an OEM kind of way .

Alan

 

[Sam]

Yes, well, sort of...

Imagine a box which is divided into two halves with the wall separating them being a rubber membrane.

One half of the box is connected by a pipe to the intlet tract right next to the throttle body, the other half connects to another pipe that routes into the passenger footwell.

Energy pulses back from the throttle body make the membrane vibrate causing sound to go from the other non pressurised side of the box into the cabin.

So, in theory at least, it is actual induction noise...

View attachment 171108

Crazy. I've just done a quick Google and a lot of new cars use these now.

 

[_Tom]

Crazy. I've just done a quick Google and a lot of new cars use these now.

Some minis have them. I think they call theirs the "sound machine" though..lol

 

[Sir_Dave]

Some minis have them. :wink: I think they call theirs the "sound machine" though..lol

Yup, Minis have this as well 😂

 

[MarkCup]

Yup, Minis have this as well 😂

Am I reading that graphic right...goes/sounds like a rocket?

Is it a sound symposer like the Fiesta or artificial through the speakers?

I'm going to clean up and re-attach mine this weekend, see if I can bring it back to life and making noise again as I miss the sound.

 

[Sir_Dave]

Am I reading that graphic right...goes/sounds like a rocket?
Is it a sound symposer like the Fiesta or artificial through the speakers?
I'm going to clean up and re-attach mine this weekend, see if I can bring it back to life and making noise again as I miss the sound.

God only knows, i just lol at the "maximum go-kart feel".
Probably speaker based knowing BMW these days, the R56 has a "noise pipe" like the ST iirc.

 

[DrR]

Hated the noise pipe on my ST, unplugged it pretty much right away.

 

[Advikaz]

My golf has one of these as well

Pretty common

 

[leeds2592]

Never noticed any change in sound in my GF's (no) Mini when in 'Sport Mode'

All it seems to do is improve the throttle response and make the steering a bit more weighty.

 

[The Psychedelic Socialist]

My golf has one of these as well

Pretty common

Different on the Golf isn't it? The Golf just has a speaker mounted on the firewall so there's no induction plumbing and no possible way it could leak boost.

 

[MarkCup]

Yar, on the Golf it's binary and artificial.

 

[Advikaz]

No idea

Vibrates the windscreen or something doesn't it?

 

[McGherkin]

Soundaktor, works like a speaker but instead of a cone it rattles the panel it's attached to IIRC.

 

[Jason_E]

The GT86 has a similar thing, handily the dust cover for one of the ciggy lighters is the perfect size to plug it up for long journeys. Not sure if that was intentional or not...

 

[dann2707]

Sadly you can't say you've lost 10bhp from it just by doing a rolling road test. Unless it was the same conditions, fixed whilst on the bed, then ran again. Good find though.

 

[_Tom]

Sadly you can't say you've lost 10bhp from it just by doing a rolling road test. Unless it was the same conditions, fixed whilst on the bed, then ran again. Good find though.

Spoil sport

 

[MarkCup]

Sadly you can't say you've lost 10bhp from it just by doing a rolling road test. Unless it was the same conditions, fixed whilst on the bed, then ran again. Good find though.

I didn't actually claim that I lost 10 bhp from this specifically...just that my rolling road result was about 10 bhp down from where it should have been.

If fixed it now but has that given me 10 bhp? I seriously doubt it for what amounts to, being generous, about a 1 psi boost gain!