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Author: Subject: i got kicked off a track day yesterday :(
daniel mason

posted on 1/3/16 at 08:20 PM Reply With Quote
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

posted on 1/3/16 at 09:16 PM Reply With Quote
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?


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Sam_68

posted on 1/3/16 at 09:29 PM Reply With Quote
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

posted on 1/3/16 at 09:38 PM Reply With Quote
did this on the mnr zzr1400 was 93 db

mnr exhaust
mnr exhaust

rear exit exhaust
rear exit exhaust

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twybrow

posted on 2/3/16 at 12:13 AM Reply With Quote
quote:
Originally posted by INDY BIRDJo
did this on the mnr zzr1400 was 93 db

mnr exhaust
mnr exhaust

rear exit 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

posted on 2/3/16 at 06:02 PM Reply With Quote
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

posted on 2/3/16 at 06:38 PM Reply With Quote
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

posted on 2/3/16 at 06:40 PM Reply With Quote
Good info. Keep the ideas and solutions coming
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bi22le

posted on 2/3/16 at 07:49 PM Reply With Quote
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!

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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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