Resonator

[mctwistuk]

Heading to see willie at meercat tomorrow to have a resonator fitted to quieten system a bit.

He has just developed a 3" system for an rs that is quieter than standard exhaust.

[fai17]

Will be interested to hear what it sounds like after fitting Chris.

[mctwistuk]

Just back from meercat and the difference is huge. Resonator fitted in centre section and a new wee addition added to just before the backbox to reduce and pretty much eliminate the cabin drone. Cracking work and would definitely recommend.

Bumped into g.macs brother whilst there but didn't realise who it was and put my foot in it by asking if he was g.macs dad lol. That's me off his Christmas card list lol.

Chris

[mctwistuk]

Photo of the new bit that willie is developing.

[fai17]

Interesting!

[mctwistuk]

Lots of physics and calculations involved but it works.

The box I ended up with is slightly different.

Edited May 4, 2013 by mctwistuk

[mctwistuk]

It is a helmholtz resonator box.

When air is forced into a cavity, the pressure inside increases. When the external force pushing the air into the cavity is removed, the higher-pressure air inside will flow out. The cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. This process repeats with the magnitude of the pressure changes decreasing each time.

The air in the port (the neck of the chamber) has mass. Since it is in motion, it possesses some momentum. A longer port would make for a larger mass, and vice-versa. The diameter of the port is related to the mass of air and the volume of the chamber. A port that is too small in area for the chamber volume will "choke" the flow while one that is too large in area for the chamber volume tends to reduce the momentum of the air in the port.

Chris

[corsa]

Feck that, i went for the more simpler approach, full 3" straight through, no pussying about ;-)

[mctwistuk]

Feck that, i went for the more simpler approach, full 3" straight through, no pussying about ;-)

Oft man but now you are deaf lol. G.macs brothers rs4 was there and it was loud

[johnmacdonald]

WRX PPP originally had a 2.5" straight through centre pipe, but drone at certain crusing speeds was totally unacceptable. Replaced it with an Afterburner centre with small integrated performance silencer. Nice Scooby rumble, but cabin noise not much different compared with OEM huge and performance restricting resonator.

John

[g1983]

Straight through or go home

[Jimmy321]

Just back from meercat and the difference is huge. Resonator fitted in centre section and a new wee addition added to just before the backbox to reduce and pretty much eliminate the cabin drone. Cracking work and would definitely recommend.

Which exhaust do you have fitted? I have a cobra on my WRX and it's great on A and B class roads but it can be a pain on the motorway as the cabin drone is at it's worst at 70-75MPH in 5th to the point I would not have the kid sit in the back should I decide on a day trip over 50 miles.

Also with the resonator fitted did it need a remap?

[mctwistuk]

I have a meercat custom resonated centre section and backbox with a oem downpipe. I am unsure as to what effect this would have on needing a remap etc but there was no performance loss. It may be worth speaking to willie at meercat to get his views. It certainly does make the car more long journey friendly.

Willie's contact number is 01505685235

[Jimmy321]

OK sounds good, cars running at 280BHP and I would like to keep it that way without the motorway cabin drone. I work in Hillington so it's not far from me.

[Bryan d]

Dis the sistem help in the emissions as my car fails every time and have to fit the cat and its a pane in the butt

[mctwistuk]

Dis the sistem help in the emissions as my car fails every time and have to fit the cat and its a pane in the butt

Won't help with emissions as only cats will do that I think.