Noisy Exhaust

[Dannyb]

I'm thinking of changing my Stainless steel weelbarrow exhausts after 15 years to a less noisy back box. I like the look of the GT6 backbox with the twin pipes.
If I remove the silencers along with the Y shaped pipe, is there an off the shelf pipe I can use between new backbox and the remaining exhaust pipe.
Also would I notice a lot of difference in the noise level.It is just getting a bit too much on long runs.

[yorkshire_spam]

I had a similar issue on my Spitfire, after the 2015 10CR I had ringing in my ears.

Instead of replacing the small twin back-boxes I added a resonator to the centre section.

It's not a LOT quieter, but it's taken the edge off so that it's not uncomfortable on long runs.

[Clive]

IIRC the sports system (AKA wheelbarrow) exhaust is the same for spit and GT6, so yoir spit may have an adaptor at the front, or maybe a 4 branch? So you could just fit a GT6 centre and rear box? Some GT6 have a middle box too.

I feel your pain, I gave up on the sports exhaust. I initially added a centre box, but then used a 16" and 30" long, 4" diameter pair of boxes at the rear, along with the 18" long centre. That is 64" of straight through box, seems unrestrictive and when tested at Castle Combe was 85db, which is very acceptable (98 last time, that was with centre box and the sports boxes, hellishly loud!)

[Dannyb]

I do have a resonator on mine and still find it too load

[Dannyb]

I was thinking about one of these.

[GT64fun]

Danny

I've had my GT6 Mk2 since 1978 and in that time have used a mild steel pattern Mk2 silencer a pattern mild steel Mk3 silencer, oval and round TT twins and most recently a second hand stainless twin system of unknown origin. The issue with the mild steel stuff is that it just didn't last.

The twins have all been used with a mild steel Mk3 centre box and my current set up (somewhat unexpectantly) is really quite nice. It actually sounds good and is definitely not too noisy and if attention is paid to the rear fixings does not reduce ground clearance too much.

I have thought about reverting back to a Mk3 transverse silencer, but I would like to know what was inside it first, as from the outside it looks as though there must be lots of sharp corners etc. The other option would be to design a bespoke alternative possibly using clever baffles rather than just perforated tubes and packing (as per a Magnaflow), but that is probably a 'future project' and the list of those is growing!

Ian F

[sparky_spit]

Hi Danny - I bought and fitted one of these to my Spitfire, which has a single box Pheonix sports exhaust.  You'd need 2 of course.

https://www.merlinmotorsport.co.uk/p/jetex-universal-decibel-insert-2-5-inch-u936330

In scrutineering for CMC rallies it went from 96db down to high 80's (I can't remember exactly what) but the scrutineer was much happier and it is noticeably quieter in the car and I've not really noticed any drop in the performance.

[Dannyb]

Hi Michael,

Never thought of an insert and much cheaper option. When I had a motor bike I used one on the Goldstar exhaust and that made a big difference especially for the neighbors.

 

[Dannyb]

I take it these fit in the pipe rather than in the end of the silencers. so could i just fit one in the straight bit of the pipe rather than two in each part of the Y pipe. our would that not be as efficient.

[thescrapman]

Danny, the noisiest exhaust I have ever had on a Spitfire was a stainless Semi Sports GT6 style  silencer. 

BAAAARRRRRRRRRRRRRRRRRPPPPP POP POP

[sparky_spit]

Danny, no they are designed to push into the tail pipe of the silencer, held in place with a bolt through a drilled hole. It would fit into the single pipe before the silencers of course, but I'm not sure if it would work that way or not, taking into account gas flow dynamics and such stuff. They might need to be near the end of the system to work properly.

Hopefully some clever person may pop up on here with an expert answer.

[Dannyb]

Thanks Michael, So that the same as I had for the motorbike which worked very well and of course easily removed. I shall go down that route and report back.

 

Thanks

      Danny

[sparky_spit]

Quoted from Dannyb-

Thanks Michael, So that the same as I had for the motorbike which worked very well and of course easily removed. I shall go down that route and report back.

 

Thanks

      Danny

I too have one in the exhaust of my Enfield 500. It came to me with one of Hitchcocks straight-through silencers fitted, as the standard Enfield pea-shooter silencers sound and look horrible.  It gave a nice rich sound, just like a 50's/60's 500 single should, but last year I had an incident with a young girl on a horse in a country lane which very nearly ended badly. I felt terrible and have since fitted a Hitchcocks adjustable baffle which has quietened it down, but kept the same nice tone.