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cliftyhanger
May 24, 2017, 7:40pm Report to Moderator

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As the spitfire is finally on the road, and gradually getting all the niggles sorted.
However, a problem is the exhaust.It uses a 2 1/4 pipe through to the rear, and initially I tried am oval straight through box, from some turbo escort thingy IIRC. However, it is only 14"long, and makes my ears bleed.
As a temporary stopgap, I put a single, smaller bore box on (1 3/4") and although quieter, it has had a very noticeable effect on performance

So I have some options.
1. A pair of rear boxes. I can fit 2 5" diameter boxes, each 1 3/4" diameter, (allowing for boundary effects, it is the same as a single 2 1/4 pipe) and 18" long. In parallel, like the wheelbarrow type of exhaust but at an angle under the boot floor)
2. again 2 boxes, one after the other but joined with a 180 degree pipe, mounted across the car under the boot. Again 5" diameter, but 2 1/ bore. And I could get one 18", and the other 30" long.

Any advice? or other alternatives?  (it needs the 2.25" bore!)


Clive Senior

Location-Brighton, East Sussex
Foxy is here, 1500od tax exempt Toledo. Now has the decent engine back in Slant 4 engine bolted in, sprint box and axle.Now has fresh MoT. Needs paint though.
Spitfire Zetec project is started work progressing slooooowly on the road!
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thescrapman
May 24, 2017, 7:55pm Report to Moderator

Colin Wake
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Evening Clive

I purchased a box from Custom Chrome many moons ago for the Moss (it was one for a Westfield I think) that had a clever thing inside it to reduce noise, and it worked really well, way too well in fact, you could barely hear the exhaust and it was only 2ft from my ear!!

So I removed it!

DIVER I think it was called. Still for sale now inside their Cherry bombs.

http://www.custom-chrome.co.uk/Cherrybombs.html






Schadenfreude expert and collector of assorted rusty Triumphs on the Essex/Suffolk Border.

2010, 2011, 2013, 2015 and 2016 CT Navigators Championship winner.

10CR 2005, 2007, 2009, 2011 2013 - RBRR 1990, 2006, 2008, 2010, 2012, 2014, 2016 - Nachtrit 2006, 2007, 2008, 2009, 2012 - Chinese rally 2007, 2008, 2009, 2010, 2011 - HCR 2009, 2011, 2012, 2013 (3rd place), 2014. 2015, 2017

On the road.
1968 Spitfire Mk3 : 1973 TR6 : 1967 Herald 1200 Estate 1970 : 1968 Mk1 2.5PI 1968
Off the road
1967 Moss Monaco (Mk1 GT6 based) : 1970 Spitfire Mk4 : 1970 Mk2 2000 auto  : 1964 Mk1 2000  : Mk2 2.5PI
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cliftyhanger
May 24, 2017, 8:58pm Report to Moderator

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Hmm, I believe the DIVER has baffles in it. Something I want to avoid as they cause extra restriction.
After all, I need every BHP I can muster!


Clive Senior

Location-Brighton, East Sussex
Foxy is here, 1500od tax exempt Toledo. Now has the decent engine back in Slant 4 engine bolted in, sprint box and axle.Now has fresh MoT. Needs paint though.
Spitfire Zetec project is started work progressing slooooowly on the road!
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thescrapman
May 25, 2017, 6:22am Report to Moderator

Colin Wake
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They are not really baffles but a couple of ramps in the perforated liner.

You can see right through the silencer


Schadenfreude expert and collector of assorted rusty Triumphs on the Essex/Suffolk Border.

2010, 2011, 2013, 2015 and 2016 CT Navigators Championship winner.

10CR 2005, 2007, 2009, 2011 2013 - RBRR 1990, 2006, 2008, 2010, 2012, 2014, 2016 - Nachtrit 2006, 2007, 2008, 2009, 2012 - Chinese rally 2007, 2008, 2009, 2010, 2011 - HCR 2009, 2011, 2012, 2013 (3rd place), 2014. 2015, 2017

On the road.
1968 Spitfire Mk3 : 1973 TR6 : 1967 Herald 1200 Estate 1970 : 1968 Mk1 2.5PI 1968
Off the road
1967 Moss Monaco (Mk1 GT6 based) : 1970 Spitfire Mk4 : 1970 Mk2 2000 auto  : 1964 Mk1 2000  : Mk2 2.5PI
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cliftyhanger
May 25, 2017, 4:32pm Report to Moderator

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Hmm, may have to investigate further....

What I don't want is something that is painful on long journeys, and ideally passes trackday noise tests.

But it seems very few (ienone) people can say what will definaely work and do exactly what I want (although I appreciate all pointers!)


Clive Senior

Location-Brighton, East Sussex
Foxy is here, 1500od tax exempt Toledo. Now has the decent engine back in Slant 4 engine bolted in, sprint box and axle.Now has fresh MoT. Needs paint though.
Spitfire Zetec project is started work progressing slooooowly on the road!
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John Bonnett
May 25, 2017, 5:37pm Report to Moderator

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Quoted from thescrapman
They are not really baffles but a couple of ramps in the perforated liner.

You can see right through the silencer



Thank you for the link.

At 4 inches in diameter I don't think one would fit between the chassis rails like the GT6 resonator box which is a shame because it would have been a good solution.

So I am looking at replacing the wheelbarrow exhaust with a standard GT6 system and hoping that it will be significantly quieter and not take the edge off the performance because of restricted gas flow.


La Coupe Florio 2015
https://www.youtube.com/watch?v=4-rtCbygnIM
GT6 to Spain
http://www.youtube.com/watch?v=RtFH-Q3n2Gg

Located Whiddon Down Devon
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GT6 M
May 25, 2017, 7:54pm Report to Moderator

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Clive, wot ye need is a center box, aboot 3 3/4- 4 inch or moer across
it,ll fit IF the chassis rails are turned doon wards, which are easy done wid some adjustable spanners, workin yer way along the chassis

OR, and, can squash the sides up a wee bit, so gives even moer room
I squasehed mine up, cos ex pipe kept on wanting t,go to ya side !!

its med mine v v quiet
And, ye can also re pack the rear boxes

Note,me old Falcon boxes, they have a thick tail pipe
wid extra sound deadening bits in there

Most of the wheely barra type,aint got  this
its moer so needed on 4 pots, as it gets rid of that orrid 4 pot rasp,

center box , an mek it as long as ye can
eva ratch thru the album, see wots wot





M


One does not have to know how a thing works, to know that it is not working right

Ye div,nt efta no ooa thing wuks, t,no its nut wuk,n reet.







Scaryport,��Cumbria,.
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thescrapman
May 26, 2017, 4:09pm Report to Moderator

Colin Wake
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Clive

I think Custom Chrome to a "design" service, might be worth a call with what you want.

They do also do a range for race cars, where noise and performance would be of prime concern.

Cheers


Schadenfreude expert and collector of assorted rusty Triumphs on the Essex/Suffolk Border.

2010, 2011, 2013, 2015 and 2016 CT Navigators Championship winner.

10CR 2005, 2007, 2009, 2011 2013 - RBRR 1990, 2006, 2008, 2010, 2012, 2014, 2016 - Nachtrit 2006, 2007, 2008, 2009, 2012 - Chinese rally 2007, 2008, 2009, 2010, 2011 - HCR 2009, 2011, 2012, 2013 (3rd place), 2014. 2015, 2017

On the road.
1968 Spitfire Mk3 : 1973 TR6 : 1967 Herald 1200 Estate 1970 : 1968 Mk1 2.5PI 1968
Off the road
1967 Moss Monaco (Mk1 GT6 based) : 1970 Spitfire Mk4 : 1970 Mk2 2000 auto  : 1964 Mk1 2000  : Mk2 2.5PI
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cliftyhanger
May 26, 2017, 6:14pm Report to Moderator

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Thanks Marcus and Colin.
Marcus, I have a 2 1/4 main pipe, and that is pretty tight to the rails. I may just get a 3 1/2" silencer in there, but it is only 1 1/4" bigger diameter (or the radius is only 5/8" bigger) than the pipe. So small I am doubting it will be effective.

Colin, I may give CC a call, they may help me decide, see if I can pick their brains for information!


Clive Senior

Location-Brighton, East Sussex
Foxy is here, 1500od tax exempt Toledo. Now has the decent engine back in Slant 4 engine bolted in, sprint box and axle.Now has fresh MoT. Needs paint though.
Spitfire Zetec project is started work progressing slooooowly on the road!
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DaveKent
May 26, 2017, 6:58pm Report to Moderator

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Clive
Try Chris Tullet Exhausts in Aylesbury, they are very knowledgeable, helpful and will design and make you a proper exhaust.


Club Triumph Member since 1985, and proud of it!!!
RBRR Entrant and Finisher! 1986,1988,1990,1992,1994,1996,1998,2000,2002,2004,2006,2008,2010,2012,2014,2016
HCR Entrant and Finisher! 2005,2006,2007,2008,2009
10CR 2009, 2015
1972 Spitfire MKiv� nice !!
1974 Toledo


http://www.dakstechnicaltransport.co.uk
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GT6 M
May 27, 2017, 3:22pm Report to Moderator

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Clive, did ye read the bit aboot ..bending doon the chassis rail lips
it,ll give another inch,ish
an inch is alott wen ye aint got much int first spot,!!!

M


One does not have to know how a thing works, to know that it is not working right

Ye div,nt efta no ooa thing wuks, t,no its nut wuk,n reet.







Scaryport,��Cumbria,.
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cliftyhanger
June 4, 2017, 6:04am Report to Moderator

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Been busy
18" long 3 1/2" diameter straight through silencer, 2 1/4" bore. The chassis rails have received the attention of Mr grinder and Mr mig
Seems to have helped a bit. Plus I found an old Supertrapp silencer to use as a back box. With all the "rings" I had used, it seems to be pretty OK in terms of sound now, but the 2" bore of the Supertrapp may be restrictive, the 2 1/4" is the minimum recommended size for the engine in use. (surprisingly 12% bigger internal bore, but the effect will be more than that as less boundary effects)



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Clive Senior

Location-Brighton, East Sussex
Foxy is here, 1500od tax exempt Toledo. Now has the decent engine back in Slant 4 engine bolted in, sprint box and axle.Now has fresh MoT. Needs paint though.
Spitfire Zetec project is started work progressing slooooowly on the road!
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cliftyhanger
August 5, 2017, 6:06pm Report to Moderator

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OK, 2 months on I have cracked it.

I bought 2 further boxes, and some bends. The boxes are both 4" diameter with 2 1/4" bore to match the system. One 10" and one 30" (yep, that is pretty long)

The system now has a total of 18" of 3 1/2"box and 40" of 4" boxes. All straight through so efficient in terms of power.
And it now sounds rather good, no drone or bark, so just what I wanted.



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Clive Senior

Location-Brighton, East Sussex
Foxy is here, 1500od tax exempt Toledo. Now has the decent engine back in Slant 4 engine bolted in, sprint box and axle.Now has fresh MoT. Needs paint though.
Spitfire Zetec project is started work progressing slooooowly on the road!
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ferny
August 5, 2017, 8:15pm Report to Moderator

Mr Hoppy!
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Looks like a hungry snake ate a rabbit then a hare.


Acclaim - fully working and on the road
13/60 Herald - mx5 powered and other such fun things, legal enough...
Mk1 2000 - it's still alive, just sleeping
Expert 815d - the slug

If in doubt, do up until you hear the crack and then go another 1/4 turn to ensure tightness.
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cliftyhanger
August 5, 2017, 8:41pm Report to Moderator

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Talking of which, the cornsnake has just shed and is now looking peckish...

But back to exhausts. Having asked and not got any definitive answers about what makes a quiet exhaust, this was all a bit of a punt. I know larger boxes are quieter, but no answers about shorter ovals v longer round boxes, and the relationship between diameter and length. Still no answers, but a long silencer does seem to work!


Clive Senior

Location-Brighton, East Sussex
Foxy is here, 1500od tax exempt Toledo. Now has the decent engine back in Slant 4 engine bolted in, sprint box and axle.Now has fresh MoT. Needs paint though.
Spitfire Zetec project is started work progressing slooooowly on the road!
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