34 replies to this topic

[Stimpy]

Ok - I have a fire breathing 140 bhp s/charged mini.

 

You can imagine the noise that comes out of the back.

 

Ok, some of you will become queazy from what I am about to say.

 

It's too loud.

I have a wonderful stereo system I can't hear, I'm not allowed on Castle Combe and I set parked car alarms off - which annoys the neighbours .

 

So my question is - how do I get it quiet (without completely un-tuning it)

 

Minispeed mentioned more silencers but then I thought about gas flow and how that could be affected (would I lose bhp?)

 

Then I had an eureka moment.  Ok - this might not be do-able but....

 

Can you have one pipe coming from 2 cylinders and another for the other two which follow a path to 2 separate silencers then join to the single silencer at the very rear of the mini (DTM style)?  I've seen some really good flex-exhaust (from CBS) which is very adaptable and flexible.

 

I'm just not sure about the 2 pipes for 2 cylinders thing.

 

Any ideas?  Has anyone else tried such a thing?

 

I'd like it to sound more like a standard ford cosworth rather than standing 2 feet away from 10 trumpet players.

 

Thanks in advance

Steve

[Archa]

First problem I can think of with that is the A series head only has 3 exhaust ports.

 

as for actually running multiple pipes, if you can make them fit then yeah go for it, not sure how it would affect performance but definitely having more silencers should theoretically make it quieter. 

 

Paul.

[mk1coopers]

Speak to Maniflow, they should be able to to help get the noise down

[scaffers]

heres your only answer

 

[ibrooks]

What's your current exhaust system like? It obviously flows enough gas to allow the engine to make 140 ponies.

 

Assuming it's an LCB joining to a single pipe which then goes back to a single silencer.

 

The manifold and centre section obviously flow enough and give enough of a scavenge effect. You need more silencing without restricting gas flow.

 

A resonator in the centre section might do the trick - they don't tend to impede gas flow much if sized correctly.

 

Maybe you could run a larger silencer - the bigger a silencer can be the more silencing you can get whilst maintaining gas flow. My MX5 makes similar power to your Mini on the factory exhaust and that's now exactly loud but the silencer is huge in comparison to most Mini silencers (but the pipes aren't much bigger).

 

You could add a Y-piece at the end of the centre section and run two silencers in parallel. The effect on gas flow is very similar to resistors in parallel in an electronic circuit. With care and lots of exhaust bends you might be able to get them in the space inside the rear subframe and have the tailpipes exiting together somewhere sensible but the best way I've seen of doing it was to remove the battery box and wheel well to give a flat boot floor and have the two silencers effectively mirror image each other with the tailpipes exiting at either side of the rear valance in the original position and it's mirror image.

 

More silencing is the only answer but that doesn't have to mean more restriction.

 

Iain

[Ethel]

heres your only answer

 

How many times  do we have to remind people not to give inaccurate advice if you don't know the subject properly  

 

[Yoda]

If i can have all the wheels in green, i'll take the skates 

 

 

But failing that, as has been said, assuming you have an A-series, split into two large silencers after the tunnel at the rear or speak to an exhaust specialist manufacturer like Powerflow who can fabricate exactly what you need.

 

trying to take two pipes all the way from the front to rear of the car will cause headaches in design.

Edited by Yoda, 21 June 2013 - 10:36 AM.

[mike.]

What exhaust system do you have now? 

 

You won't be able to run separate exhausts for different cylinders because theres no room under the car for that.

[Stimpy]

First problem I can think of with that is the A series head only has 3 exhaust ports.

 

as for actually running multiple pipes, if you can make them fit then yeah go for it, not sure how it would affect performance but definitely having more silencers should theoretically make it quieter. 

 

Paul.

You have just reminded me about the 3 ports.  Shows how technical astute I am!  I guess 2-to-1 and 1-to-1 would def be an imbalance - dammit.

[Stimpy]

Speak to Maniflow, they should be able to to help get the noise down

Will do - ta.

 

Am I simply ignorant or is there something scientific about a 500 hp Merc running as quiet as draft of wind but the mini barks like a demented bulldog?  If you took the exhaust off the merc and the mini the merc WOULD be louder - so it's nothing to do with cabin insulation (besides you can hear it outside the car anyway).  It's always perplexed me as a Merc doesn't have 20 silencers under it's guts.

[Stimpy]

heres your only answer

 

Nice looking model.  I particularly like the extra luggage space.   I can't see the exhaust though - is it integrated? OR is it that funny thing sticking out of the bottom between the tyres?

[mk1coopers]

[/quote]
You have just reminded me about the 3 ports.  Shows how technical astute I am!  I guess 2-to-1 and 1-to-1 would def be an imbalance - dammit.[/quote]

That's what a LCB does before they link into one pipe

[Stimpy]

See my points - please ...

What's your current exhaust system like? It obviously flows enough gas to allow the engine to make 140 ponies.

 

>> I'm assured its all maniflow - I left it to minispeed.  I leave certain things to the experts and I can't do zorst stuff - no ramps and no flame throwers

 

Assuming it's an LCB joining to a single pipe which then goes back to a single silencer.

 

>> Actually - looking under it goes through something called a 'resonator'.  That sounds like 'make me bark' to me - what does the resonator actually do? Ta

 

The manifold and centre section obviously flow enough and give enough of a scavenge effect. You need more silencing without restricting gas flow.

 

A resonator in the centre section might do the trick - they don't tend to impede gas flow much if sized correctly.

 

>> Should have read-ahead.  D'OH!

 

Maybe you could run a larger silencer - the bigger a silencer can be the more silencing you can get whilst maintaining gas flow. My MX5 makes similar power to your Mini on the factory exhaust and that's now exactly loud but the silencer is huge in comparison to most Mini silencers (but the pipes aren't much bigger).

 

You could add a Y-piece at the end of the centre section and run two silencers in parallel. The effect on gas flow is very similar to resistors in parallel in an electronic circuit. With care and lots of exhaust bends you might be able to get them in the space inside the rear subframe and have the tailpipes exiting together somewhere sensible but the best way I've seen of doing it was to remove the battery box and wheel well to give a flat boot floor and have the two silencers effectively mirror image each other with the tailpipes exiting at either side of the rear valance in the original position and it's mirror image.

 

More silencing is the only answer but that doesn't have to mean more restriction.

 

>> That's some good info - eternally thankful - it's given me ideas.  I mentioned CBS - they produce a corrugated exhaust pipe so in theory a couple of silencers could run outward and back inward to a third one.  I'll email maniflow as has been recommended here.

 

Iain

 

>> Thanks again Iain

[Stimpy]

If i can have all the wheels in green, i'll take the skates 

 

 

But failing that, as has been said, assuming you have an A-series, split into two large silencers after the tunnel at the rear or speak to an exhaust specialist manufacturer like Powerflow who can fabricate exactly what you need.

 

trying to take two pipes all the way from the front to rear of the car will cause headaches in design.

"Powerflow"  - I'll look them up.  Ta.

[samsfern]

I believe powerflow are based in ashford kent.