21 replies to this topic

[nicklouse]

Ok this is above my knowledge level but maybe someone on here knows a thing or two.

 

I am changing the exhaust again….. but it got me thinking.

 

rolled tip. Straight cut. Slash cut?

 

I am thinking that a rolled tip gives better flow than a straight cut with about the same sound level?

 

but then slash cut (facing the ground) ?

 

presuming both pipe are the same material and horizontal/parallel to the ground.

 

forget looks. More interested in performance and less noise.

[Steve220]

Overall, the tip has very little to do with the sound/noise. However, each will have an attribute. It also depends on what 'noise' you're trying to reduce. If an overall reduction, rather than targetting a certain set of frequencies (usually higher ones cause increased dB), use a double skinned tip.

[JXC Mini GT]

My mini had a RC40 twin box exhaust system with a straight cut tailpipe, the tailpipe was quite short, the car was quite noisy at motorway speeds so I purchased a Maniflow van pipe extension which has a rolled tip, the car is much quieter now with the new tailpipe.

 

It may be my imagination but I think the car runs better now than before.

[MiNiKiN]

If you want noise reduction it might be wise to let the tail pipe face downwards, so the tarmac will act as an additional damper.

 

Benefit is you can also use your Mini as leaf-blower for the driveway

[Pete649]

If you want noise reduction it might be wise to let the tail pipe face downwards, so the tarmac will act as an additional damper.

 

Benefit is you can also use your Mini as leaf-blower for the driveway

 

And if the exhaust noise is borderline this trick makes it more difficult to obtain an accurate reading by the track day noise testers as they can't hold the sound level meter the set distance away directly from the exhaust exit.

Edited by Pete649, 07 June 2021 - 02:55 PM.

[Tones61]

1275 mpi,
Fast road head,
Stainless maniflow lcb,
Stainless twin box rc40,
Play mini tail pipe welded on,

Low deep bass sound,

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[nicklouse]

1275 mpi,
Fast road head,
Stainless maniflow lcb,
Stainless twin box rc40,
Play mini tail pipe welded on,

Low deep bass sound,

And total *******. Sorry.

[nicklouse]

Going for the impossible sound check exit.

 

[Tones61]

Hi nicklouse,
In what way don't you like it?
It's on my road car,
Recommended upto 100 bananas ?
Thanks for input
Tony

[Tones61]

1275 mpi,
Fast road head,
Stainless maniflow lcb,
Stainless twin box rc40,
Play mini tail pipe welded on,

Low deep bass sound,

And total *******. Sorry.

Hi nicklouse,
In what way don't you like it?
It's on my road car,
Recommended upto 100 bananas ?
Thanks for input
Tony

[Midas Mk1]

1275 mpi,
Fast road head,
Stainless maniflow lcb,
Stainless twin box rc40,
Play mini tail pipe welded on,

Low deep bass sound,

And total *******. Sorry.

Hi nicklouse,
In what way don't you like it?
It's on my road car,
Recommended upto 100 bananas ?
Thanks for input
Tony

Don’t worry, he’s a ****.

[nicklouse]

 

 

1275 mpi,
Fast road head,
Stainless maniflow lcb,
Stainless twin box rc40,
Play mini tail pipe welded on,

Low deep bass sound,

And total *******. Sorry.

Hi nicklouse,
In what way don't you like it?
It's on my road car,
Recommended upto 100 bananas ?
Thanks for input
Tony

 

How does it answer my question? It does not.

 

also the larger exhaust tip causes extra reverse sound waves in the exhaust.

 

playmini exhausts and always been noise over performance. 

[nicklouse]

Overall, the tip has very little to do with the sound/noise. However, each will have an attribute. It also depends on what 'noise' you're trying to reduce. If an overall reduction, rather than targetting a certain set of frequencies (usually higher ones cause increased dB), use a double skinned tip.

Now here is another thought for your perusal.

 

let’s say you have two silencers of the same cross section but one is twice the length of the other.

 

would they dampen different frequencies?

 

both are 4x8 and one is 8” the other 16” long will have about a 1” gap between them.

 

the 16 first then the 8. 

[johnR]

I thought rolled tips were an SVA thing - in case you reverse over someone at speed they wont be injured by the sharp edges of the exhaust - like they'd care! 

[KTS]

Overall, the tip has very little to do with the sound/noise. However, each will have an attribute. It also depends on what 'noise' you're trying to reduce. If an overall reduction, rather than targetting a certain set of frequencies (usually higher ones cause increased dB), use a double skinned tip.

Now here is another thought for your perusal.
 
let’s say you have two silencers of the same cross section but one is twice the length of the other.
 
would they dampen different frequencies?
 
both are 4x8 and one is 8” the other 16” long will have about a 1” gap between them.
 
the 16 first then the 8.

Absorptive or reactive silencers ?

https://www.acoustic...5/papers/34.pdf