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Mad idea, good idea ?
Jon Ison - 13/3/14 at 09:49 PM

Been mulling over trackday noise tests.

What if I drilled a hole in exit pipe of the exhaust, welded a nut over the hole, screwed a bolt through it then welded a penny washer to the bolt inside the pipe, with the use of a lock nut out side the pipe the washer could be turned/locked into position looking a bit like a throttle butterfly?

Left wide open for minimum restriction close for noise test ?


Good idea, bad idea, just thinking out loud ?

locost 7 k - 13/3/14 at 09:55 PM

Try eBay, they have these type of things on there

owelly - 13/3/14 at 09:57 PM

It does work as that's similar to what I had up my chimneys but it's the drive-by noise tests that will get you in trouble...

Jon Ison - 13/3/14 at 10:00 PM

I never have a problem drive by, failed miserably at Oulton on static, ended up with a red bull can rammed in front end of silencer, passed test can blew out ran all day no problems, don't ask why it not noisy on the move, static tests are a pain, just the way it is.

Jon Ison - 13/3/14 at 10:01 PM

quote:
Originally posted by locost 7 k
Try eBay, they have these type of things on there


I've seen db killers but not somthing you can fix and "tune" with a spanner? Do you have a link to somthing ?

locost 7 k - 13/3/14 at 10:16 PM

http://pages.ebay.com/link/?nav=item.view&id=330949311515

I had a similar design on my old car, I had a Y piece in the exhaust with a standard silencer and a straight through with exhaust valve on the tip

locost 7 k - 13/3/14 at 10:19 PM

http://www.metropower.org.uk/forum/forums/thread-view.asp?tid=72476&start=126

Towards the bottom is my old system, one of the best mods I done

Jon Ison - 13/3/14 at 10:24 PM

Thanks, did it reduce noise significantly?

mark chandler - 14/3/14 at 08:50 AM

I have the same problem, good idea !

My car is really quiet one the drive by, it's a mixture of induction noise and panels without soundproof that are the isssue. When I had a side outlet if I stood between the wheels on the exhaust side of the car it dropped the noise reading so have dragged my exhaust out the back now.

It's still at the limit even now, this sounds like a great plan

[Edited on 14/3/14 by mark chandler]

steve m - 14/3/14 at 08:57 AM

Jon,

I like the idea of a turning penny washer as a butterfly, as my 7 is also very loud, so much so, I cannot really use the car for work
as its too noisy for a 0630 startup, now and again is ok, though

so once you have drilled the holes in your exhaust and fitted your new design, post some pics please

Steve

trikerneil - 14/3/14 at 10:36 AM

I fitted this system to a Harley once to get back some of the backpressure lost with running straight through pipes LINKY
I got enough backpressure to increase the mid-range torque but it made no difference to the noise.
I had to refit baffles for the MOT.

Neil