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PostPosted: Sun Nov 27, 2016 1:56 pm 
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I know there aren't many in Aus but thought I would ask for some opinions anyway.

What is a good exhaust setup for a B series engine in a mini? I have a cat, centre resonator and rear chambered muffler and think it is quiet outside but drones loudly inside. I am thinking it must be the interior size or something. Windows up or down and doors open and shut make a difference to the droning.
Anyone have experience with this?

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PostPosted: Sun Nov 27, 2016 8:05 pm 
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other than asking on the UK 16v forum, replicating the standard system on the honda would be the best starting point, they put a lot of R&D into getting it to perform and be quiet inside

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PostPosted: Sun Nov 27, 2016 8:24 pm 
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Cheers. One of the guys on the 16v site suggested the mounts might be too firm and in-turn causing a vibration type drone. I am using cotton reel mounts at the rear and a fairly solid original mini mount at the front of the rear subframe. Considering it doesn't drone on the outside he may have a point.

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1988 Rover mini
Restored as a 97 Sport pack
Engine - Honda B16A (WIP)
ECU - Autronic SM4
Exhaust - Custom, TBA
Dash - Carbon fibre wrapped


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PostPosted: Mon Nov 28, 2016 7:18 am 
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So long as the cotton reels are (say) rubber isolated from the body, that's probably the best you can do. The other thing to try might be heavy sound deadener under the carpets, behind the back seat etc

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PostPosted: Mon Nov 28, 2016 7:41 am 
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Yep they are rubber and not metal on metal.
I might try it with the exhaust hanging by a piece of rope to see it makes a difference. (At a stand still of course)

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1988 Rover mini
Restored as a 97 Sport pack
Engine - Honda B16A (WIP)
ECU - Autronic SM4
Exhaust - Custom, TBA
Dash - Carbon fibre wrapped


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PostPosted: Mon Nov 28, 2016 6:18 pm 
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Dutchy1978 wrote:
Yep they are rubber and not metal on metal.
I might try it with the exhaust hanging by a piece of rope to see it makes a difference. (At a stand still of course)


fencing wire lasts a long time...

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PostPosted: Mon Nov 28, 2016 7:41 pm 
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It probably needs a resonator added into the system.
Many exhausts are reasonably quiet on the outside but drone inside the car.
I doubt that the exhaust is causing drumming of the body unless the exhaust is attached very rigidly to the body.

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PostPosted: Mon Nov 28, 2016 9:08 pm 
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Phil 850 wrote:
It probably needs a resonator added into the system.
Many exhausts are reasonably quiet on the outside but drone inside the car.
I doubt that the exhaust is causing drumming of the body unless the exhaust is attached very rigidly to the body.


It has a resonator already Phil.

Image

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1988 Rover mini
Restored as a 97 Sport pack
Engine - Honda B16A (WIP)
ECU - Autronic SM4
Exhaust - Custom, TBA
Dash - Carbon fibre wrapped


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PostPosted: Tue Nov 29, 2016 1:03 pm 
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For what it's worth, mine drones too. :roll: At some stage in the future I'll be wrapping the entire length in two layers of heat-wrap, & trying to protect it somehow by covering it in.
I dunno if it will make much difference. Honda must have done a LOT of work to make sure it sounds ok inside.
I've got a 2-1/2" Stainless, cat, hotdog/resonator & muffler. The only real diff between mine & yours is I have a single outlet. I'm assuming your bracket at the back is holding the twin pipes tightly, & they are not just sitting on the metal bracket. Yes, the bracket is suspended on rubber, but the pipes could be vibrating on the bracket if not held to it.
Otherwise, you might just have to add 100kg of sound-proofing into the car. :lol:

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PostPosted: Tue Nov 29, 2016 2:34 pm 
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Consider replacing the middle resonator with a double length unit ( up to that first weld )


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PostPosted: Tue Nov 29, 2016 3:43 pm 
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Slugman wrote:
For what it's worth, mine drones too. :roll: At some stage in the future I'll be wrapping the entire length in two layers of heat-wrap, & trying to protect it somehow by covering it in.
I dunno if it will make much difference. Honda must have done a LOT of work to make sure it sounds ok inside.
I've got a 2-1/2" Stainless, cat, hotdog/resonator & muffler. The only real diff between mine & yours is I have a single outlet. I'm assuming your bracket at the back is holding the twin pipes tightly, & they are not just sitting on the metal bracket. Yes, the bracket is suspended on rubber, but the pipes could be vibrating on the bracket if not held to it.
Otherwise, you might just have to add 100kg of sound-proofing into the car. :lol:

The twin pipes are fully welded onto the muffler and the bracket welded on too. Just the rubber cotton reels between the bracket and subframe.
The Honda muffler is massive and even if I wanted to use it, it wouldn't fit without dragging on the ground. :)

Bennjamin wrote:
Consider replacing the middle resonator with a double length unit ( up to that first weld )

Yep that will be one option.
I replaced the gasket in front of the cat with a steel plate with holes and then added some steel wool in front of the plate. This made a big difference. Not ideal for long term but it reassured me that it can be quietened down somehow.

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1988 Rover mini
Restored as a 97 Sport pack
Engine - Honda B16A (WIP)
ECU - Autronic SM4
Exhaust - Custom, TBA
Dash - Carbon fibre wrapped


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PostPosted: Tue Nov 29, 2016 4:35 pm 
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So the holey plate & steel wool would give a similar effect as a turbo fan would (Except a nett loss in power) - Muffling the pulses to a steady stream of air, but making more back-pressure. Looks like Bennjamin is on the money with his suggestion of the bigger resonator.

In my case, they turned the muffler sideways to get enough room, then looped the outlet back to make it exit in the centre rear. Messy underneath but looks OK from the back. I don't think I gained much in muffler size compared to yours though.

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PostPosted: Thu Dec 01, 2016 7:18 pm 
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I think I try a bigger resonator.
Should be a relatively economical solution.
A decent exhaust shop should be able to diagnose the problem for you and install a fix. If it doesn't cure the problem they rework it at their cost.

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PostPosted: Fri Dec 02, 2016 7:26 am 
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I'd be leaning towards that rear box. Some of those twin-tip ones drone like a bastard on a 40hp mini, let alone with a VTEC at the front of it.

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PostPosted: Fri Dec 02, 2016 3:06 pm 
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Slugman wrote:
So the holey plate & steel wool would give a similar effect as a turbo fan would (Except a nett loss in power) - Muffling the pulses to a steady stream of air, but making more back-pressure. Looks like Bennjamin is on the money with his suggestion of the bigger resonator.

In my case, they turned the muffler sideways to get enough room, then looped the outlet back to make it exit in the centre rear. Messy underneath but looks OK from the back. I don't think I gained much in muffler size compared to yours though.


Steel wool and plate were removed shortly after. I just wanted to see if it worked.
I too thought about the sideways muffler but went against it as it was easier going straight through.

Phil 850 wrote:
I think I try a bigger resonator.
Should be a relatively economical solution.
A decent exhaust shop should be able to diagnose the problem for you and install a fix. If it doesn't cure the problem they rework it at their cost.

Yep. Resonator is my first option.

Stuwey wrote:
I'd be leaning towards that rear box. Some of those twin-tip ones drone like a bastard on a 40hp mini, let alone with a VTEC at the front of it.

The rear box I have on it now is a single 2" in and out with a twin tip welded on the end. The image above was just for the resonator image.
Image

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Website: http://www.dutchysmini.com/
Facebook page: https://www.facebook.com/OLDSchoolMini/

1988 Rover mini
Restored as a 97 Sport pack
Engine - Honda B16A (WIP)
ECU - Autronic SM4
Exhaust - Custom, TBA
Dash - Carbon fibre wrapped


Last edited by Dutchy1978 on Fri Dec 02, 2016 10:00 pm, edited 1 time in total.

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