Proflow quad pipe exhaust silencer noise mitigation

[Big G]

In my last thread I was pretty excited with my Proflow Quad pipe and still am apart from an increase in cabin noise (booming resonating) at higher speeds even with the quiet option silencer a little annoying on the motorway/duel carraige ways.
So I have a plan to mitigate the noise.
Part 1  - I made a 600mm x 500mm pad from Rockwool 40mm insulation (fire batt so quite dense not the light fluffy stuff used for lofts) then wrapped this in 2 layers of foil barrier membrane and foil taped the joints. I then wrapped this around the exhaust main silencer and fixed with wire as a  temporary measure (experimentental at this stage and a bit short so I only actually wrapped 3/4 of the silencer, left the gap at the back)
I have basically lagged the silencer.
Result =
1. Heat of silencer is reduced, surface of lagging insulation only gets above hand hot.
2. The noise level has reduced by large margin probably the same or maybe lower than stock.
3. Still got the nice exhaust note
4. Annoying booming has gone.
The sides of the silencer are still exposed as is the down pipes/tail pipes.
My thinking is the stainless steel silencer does run a lot hotter than a comparable mild steel silencer so heat reduction is a good thing.

Part 2 - I have ordered some self adhesive noise reduction pads and will cut this to size and line the underneath of the engine lid (bonnet)

I will now make another silencer lagging pad the correct size and fix with S/S cut to size jubilee clips
I am over the moon with the initial results however does anyone think of any problems I may encounter using this method, the foil and insulation is used in fire protection so it will stand temperatures of 250C  so it won't catch fire,
All comments welcome
Cheers
George

[loadswine]

I did a similar thing on my last roadster, for the heat management in my case though. It worked fine. I didn't use foil, but did use rockwool in 'pillows' made from a glass mat type material.
Yours sounds fine, as far as I can tell.

[Eastsoutheast]

Any chance of some pics please, my other half has refused to drive ours since I changed the exhaust and I would love to make it quieter.

Thanks
Brian

[loadswine]

P7021755 by loadswine, on Flickr

You can see the grey material, just below the chargecooler on my turbo installation. I had two narrow pillows for mine.
 Be interested to see the solution on the Pro flow.

[Big G]

Hi
My long jubilees will be here next week and sound proofing pads, I will fit the permanant silencer lagging next weekend and post some pics, all I can say is the difference is significant, well worth doing and keeps she who must be obeyed happy into the bargain.
cheers
Big G

[tomaky]

Would be interesting to see this as its something id be interested in. Can get irritating on top up drives.

[Eastsoutheast]

P7021755 by loadswine, on Flickr

You can see the grey material, just below the chargecooler on my turbo installation. I had two narrow pillows for mine.
 Be interested to see the solution on the Pro flow.

A very tasty looking engine bay, must have been a fantastic car, thanks

[Big G]

Hi  All
Managed to scrounge some jubilee clip so I have permanantly installed the noise mitigation insulation, I managed to cover right round the full body of the Proflow silencer see photos of job and few extra ones of my MR2 and toyota collection Hilux and a Yaris (not in pictures). I am out for a test drive this afternoon so I will report back tonight.
Cheers
Big G

[Eastsoutheast]

Watching this thread like a hawk as really need to quieten my system.

Awesome looking Hilix.

[Big G]

Right the verdict.
The sporty tone is still there with a little burble barble on the over run.
70 mph cruising I would say is only slightly louder than stock, but the booming resonating sharp annoying tone has gone.
On a private test track 80mph is still ok, above 80mph to 85mph the noise level rises but mainly from the tail pipes and obviously you ears are less than 2 metres from the source of noise.
After a 30 mile 70 mph run you can still touch the silencer lagging, still a lot of heat from the manifold/pre cat housing (original heat sheild fitted) but I guess thats normal.
Anyway most definately a worthwhile exercise, I will see how the sound proofing pads work next weekend on the rear bonnet lid. No complaints from the wife so it can't be too bad and she has hearing like a spy satellite. I will keep you all posted.
Cheers
Big G

[Big G]

Just been out for a quick spin with the roof down and it sounds amazing so because I intend to drive mostly top down I am happy, I will still fit the panel sound deadening pads. I am going to play around with some home made decibel killers for the tail pipes but  it it is running so well I probably won't do much more, if I can improve slightly the roof up cabin noise I will report back.
Anyway really enjoyed my little thrash so bring on the summer.
Cheers
Big G

[loadswine]

I think you will find it tones down a bit with a few miles on it as well. I have had new systems do that before.

[Big G]

Thanks Loadswine
would that be due to carbon/soot build-up perhaps.
Cheers
Big G

[feralcrew]

Could you post a link to the materials you used? English is not my native language and it's a bit difficult to make out what exactly you used. And I would ver happy to queieten my exhaust at least a bit!

[Big G]

Hi Feralcrew
Materials used
40mm rockwool firemaster insulation slab 45KG/m
Foil vapour barrier
Foil Tape
Endless Jubilee clips.

Cheers#
Big G

[Big G]

Hi All
Another update on the proflow quad exhaust, the exhaust does seem to have become a bit muted with use, so cruising with the hood up is ok, with the hood down it sounds brilliant with a nice hollow howl on start up, the tone under acceleration is very nice and it seems to pull a lot better from tick over to 3000 rpm.
So to summerise I am now very contented with the exhaust, I have left the main silencer lagged that does reduce the drone when cruising top up.
Cheers
Big G

[dan944]

Just a quick question on this. Where did you get your insulation from. I can only find it in huge quantities :/

[Big G]

Hi Dan
Borrowed the insulation materials from work

[mrzwei]

Hi Dan
Borrowed the insulation materials from work

In the military they call that 'long loan'   s:lol: :lol: s:lol:

[1979scotte]

In my job we just call it perks.

[Anonymous]

And in Essex it called a 5 finger discount  s:lol: :lol: s:lol:

[dan944]

Haha. Fair one. I guess I'll have to keep an eye out.
Thank tou

[Big G]

I finally got round to making 4 decibel killers for my proflow quads, they look like long top hats with a flange round the brim of the top hat, made of stainless steel perforated sheet. They are insert deep into the exhaust tips and secured with a pop rivet.
Still got a great sound but about the same noise as the stock exhaust, high speed cruising no problem, no booming/droning.
Very happy with the system now
Big G

[kiril89]

Hey Big G! Thank you for the write up!

Will definitely attempt to do something similar to my TTE backbox (it's a bit too boomy for my taste on the motorways). Will start with putting some sound deadening pads on the engine lid and some heatshields.

Can you recommend what did you use? I am after something adhesive and heat resistant.

Thanks!
Kiril

[Tomo70]

On the subject of TTE back boxes. I recently had to get mine repaired. I noticed it seemed to be getting loud in the cab at motorway speeds..
Removed the back box and could hear pieces of metal moving around. Had the box opened up only to find a Brocken weld on a joint in the box and the silencer material has burnt away. The weld was repaired and the exhaust re packed then weld up. A vast improvement now at motorway speeds.   s:) s:)