daniel mason
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| posted on 1/3/16 at 08:20 PM |
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Just get a decent large silencer like raceco and a good airbox. That should improve things.
I'm always dangerously close on static tests at around 104db which is sometimes an issue on drive by
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AntonUK
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| posted on 1/3/16 at 09:16 PM |
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What 'bungs' do you guys use? Mine and a lot of others have a 90 deg bend near the tip so can use the usual straight bungs you see for
sale. Is there a curved one that I've not seen?
Photo of mine:
 
Description
Build Photos Here
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Sam_68
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| posted on 1/3/16 at 09:29 PM |
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quote:
Originally posted by Slimy38
Most tin tops have the exhaust pointing straight down, or at least 45 degrees into the road. So why is it 'standard' to have the 7 exhaust
pointing straight out?
Good question.
I wonder how much influence it would have if you angled the exhaust outlet 45 degrees down and in toward the undertray, so that some of the sound
waves are 'trapped' and absorbed by bouncing them up and down between the undertray and the tarmac?
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INDY BIRD
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| posted on 1/3/16 at 09:38 PM |
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did this on the mnr zzr1400 was 93 db
 
mnr exhaust
 
rear exit exhaust
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twybrow
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| posted on 2/3/16 at 12:13 AM |
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quote:
Originally posted by INDY BIRDJo
did this on the mnr zzr1400 was 93 db
mnr exhaust
rear exit exhaust
I have to say style wise I am not a fan, but no arguments that it is clearly effective.
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CNHSS1
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| posted on 2/3/16 at 06:02 PM |
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quote:
Originally posted by Sam_68
quote:
Originally posted by Slimy38
Most tin tops have the exhaust pointing straight down, or at least 45 degrees into the road. So why is it 'standard' to have the 7 exhaust
pointing straight out?
Good question.
I wonder how much influence it would have if you angled the exhaust outlet 45 degrees down and in toward the undertray, so that some of the sound
waves are 'trapped' and absorbed by bouncing them up and down between the undertray and the tarmac?
in reality changing the angles doesn't make the pulses exiting quieter but does take the issue away as far as the drive by mics are concerned. A
friend works in exhaust design and tailpipe angles, even whether rolled in or out at the lip end, does make a big difference on a road cars noise and
tone levels. Exiting under the car would almost certainly help as the turbulation of airflow under the car from wishbones and chassis underside will
suitably disrupt the exhaust pulses, you can even claim its an ex-F1 blown diffuser ;-)
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
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Sam_68
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| posted on 2/3/16 at 06:38 PM |
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quote:
Originally posted by CNHSS1Exiting under the car would almost certainly help as the turbulation of airflow under the car from wishbones
and chassis underside will suitably disrupt the exhaust pulses, you can even claim its an ex-F1 blown diffuser ;-)
Just the fact that the sound will be bounced backwards and forwards between the tarmac and the undertray a few times (with the tarmac, in particular,
absorbing some each time instead of reflecting it onwards) ought to help, too.
Admittedly, tarmac's not a particularly good sound absorber, but it's better than nothing. As an aside, I've done some architectural
work in the past on recording studios that use specifically sound-absorbing panels - they look like the structure of egg cartons, but made out of
sound absorbent foam - and the effect is very weird indeed. You get absolutely no reflected sound, so no echo and even the loudest sound source is
very muted. Packing an aluminium tube with fibreglass quilt is a very crude approach in comparison!
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livelee
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| posted on 2/3/16 at 06:40 PM |
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Good info. Keep the ideas and solutions coming 
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bi22le
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| posted on 2/3/16 at 07:49 PM |
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Well i can throw in my potential solutions if it helps.
Im going to make an inlet plenum that can take boost, so its future proofed for SC upgrade when i get to it. Airfilter will be a pipercross vortex.
Exhaust is going to be resealed and outlet rewelded to point down more. Ill probably also buy a second silencer, mounts and tube to create a second
inline silencer.
As my mate said " it will sound like a sowing machine" !!
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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