Mazda Rotary Club

General => General Technical => Anything Engine/Performance/Tuning related => Topic started by: Archbish on December 02, 2009, 09:13:52 AM

Title: Reducing exhaust volume
Post by: Archbish on December 02, 2009, 09:13:52 AM
So, I am pretty sure I need to reduce the volume of my exhaust.  ((actually, I definitely need to reduce the volume of my exhaust))

Currently, the 1st gen is running an S5 engine with big fat T04 tubby.  The exhaust is 3" along its full length, and has a rear box that can\'t be much larger without fouling, and a midpipe.  Both are perforated tube stuffed with Stainless mesh.

The options I can see are:
1 - reduce the diameter of the exhaust.  I\'m not sure how that\'ll help with volume, but could reduce performance, right?
2 - replace the midpipe.  Is there a different baffled option that could work?
3 - put in one of those closeable openable disk things to restrict flow, and apparently reduce volume.  How effective are these?

any opinions or experience with this?  Advice appreciated!!
Title: Reducing exhaust volume
Post by: lee mills on December 02, 2009, 09:18:48 AM
Dont know if youve got the room but you could add another silencer. or change existing silencers for bigger ones.
Title: Reducing exhaust volume
Post by: AtomicRex on December 02, 2009, 09:22:57 AM
Our exhausts are extremely free flowing they are 3" and are made from Stainless
 
But the real benefit about them is that they are repackable....so you should in theory never need buy another exhaust!!  They come with a lifetime guarantee for you and your car :)
Title: Reducing exhaust volume
Post by: antnicuk on December 02, 2009, 05:49:26 PM
what rear silencer are you running and how old is it.
Title: Reducing exhaust volume
Post by: Archbish on December 02, 2009, 05:57:59 PM
Thanks for the replies chaps.  It\'s a new exhaust on the car, and a brand new silencer.  They\'ve done about 500 miles tops.

It\'s a Jetex one - I can\'t seem to get on their website at the mo, but it\'s a 3" input silencer with stainless packing.
Title: Reducing exhaust volume
Post by: turbointhebrain on December 09, 2009, 11:29:14 PM
hey archbish, i have recently taken delivery an FC (with a to4r) with the HKS "closeable flappy thing" on first test it dramatically reduces the noise to pretty much nothing, but as havn\'t had the car out on the road yeah, not sure on how much it restricts the power.  however saying that you can set the degree by how much you close it, so you could find a happy medium for town driving. will let you know once i get the car on the road
Title: Reducing exhaust volume
Post by: L18M on December 09, 2009, 11:39:39 PM
the flappy valve thing wont make it quieter than your exhaust without the flappy thing.
the flappy thing only really helps relieves pressure in the exhaust by letting gas out the flap and will only make it louder.
Title: Reducing exhaust volume
Post by: turbointhebrain on December 10, 2009, 12:42:31 AM
L18m yeah your right about the diverting flap. Had a look at some jap mags and found out that the system that I have is an a\'pexi ecv which is basically like a butterfly valve fittin inline in the exhaust! Option mag had the price down at ¥17,850, in uk money that is £125!!
E.g. http://www.nengun.com/apexi/exhaust-control-valve
Title: Reducing exhaust volume
Post by: 12at on December 10, 2009, 08:30:24 AM
I think the problem is your rear box bish.. may be you need something bigger in size like a 8" barrell really packed with stainless wire. The big silencer you got should be fine.
 
On my 12a half bridge T04r im running the smaller jetex mid that you have and a 6" barrell rear and its fine..
Title: Reducing exhaust volume
Post by: Archbish on December 10, 2009, 09:00:30 AM
Hmmmm - what brand rear box are you running??  At the moment the wastegate dumps to atmosphere, but that shouldn\'t be an issue at idle...
Title: Reducing exhaust volume
Post by: Brett on December 10, 2009, 09:16:21 AM
Have you tried not putting your foot down as hard? :Giggle
Title: Reducing exhaust volume
Post by: Archbish on December 10, 2009, 09:18:24 AM
hell, at idle it\'s enough for the deaf neighbour watching TV at the back of his very well insulated house to hear it...