I was flicking through the wiring guide from the excellent Ravensblade Impreza site (www.ravensblade-impreza.com), and I came across 'Electrically controlled muffler system' on page 54.

It shows a Muffler Control Unit (connected to the ECU) and a Muffler Actuator, which presumably is some sort of movable baffle in the exhaust.

Anyone know anything about this ? I seem to remember reading about this on other Japanese cars (Honda NSX?). Basically the idea was to give a nice quiet exhaust when you wanted it, but with the ability to change this for a full-on sound by flicking a switch.

Just curious really - but got me thinking there's a lot who would like a normal (quiet!) exhaust sound around town, with the ability to switch this to a barking WRC imitation down our favourite twisty bits......

 

Strange idea but I was toying with this concept. There are many ways of acheiving this but it would take considerable time and effort.

The std box only has 3 sections and no damping material. It has differing length tubes passing into each section to cancel out the sound waves. It is suprising that it flows as well as it does considering the tortuous path that the gas has to travel. You could get some of the tubes to rotate out and provide a straighter path for the gases (and be louder) but this would require a motor mounted somewhere outside the box etc.

It seems that the majority of all the sound deadening is done by the back box and this is where the motorisation should take place.

F

 

Floyd,
Is this the standard twin exit pipe backbox which is divided into three chambers? I fitted an STI backbox to my car last year and from reading other threads on the bbs thought the internal construction was the same on both. With the larger exit pipe on the STI item you can see straight through to the back of the silencer. The construction of the STI box is:

A tube entering the silencer off centre up and to the right as you look in from the tailpipe.
A chamber at the end of backbox which accounts for about 1/6 of the silencers length.
A straight through pipe with a few perforations leading to the tailpipe.

There is only one tube in the STI backbox.

Could you give a bit more detail on the internal layout of the standard backbox please.

 

Floyd,

Motor is exactly what the 'actuator' seems to be - I guess a solenoid.

I'll try and post up the wiring diagram tomorrow.

Cheers
Tim

 

The Legacy GTB and B4 have a electronically switched backbox, that opens to become more free flow at high rpms - not sure where the switchover is though

Paul

 

That would explain the ECU connection then.

Anyone know how easy the Legacy BB can be adapted to fit the Scoob, if at all?

 

The skyline has it as standard a dash mount switch so u could look for info those sites

 

Andrew

The box I'm talking about is the std twin pipe jobbie. It would be hard to describe in words how it is layed out but it is complicated.

pnebbs, this legacy BB sounds interesting, who's got one that I can take a look at or does anyone have a picture/details?

F