Mini exhausts
Turbo Mini Forums

Why are they so loud?

Everything apart from the pea shooter is very loud and boomy, is this nessasary for the power they produce?
I was thinking there might be merit in the miglia style of setup with a twin rear scilencer?

I mean dont get me wrong I like a good exhaust note but at certain speeds they seem too noisy? What does everyone else think?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I don't think they are that loud, just the car has bad soundproofing. Plus, drivers ear to end of exhaust is shorter than most other cars!

Bad sound proofing, thin panels. Space constraints for decent silencers.

mine doesnt seem that loud, although its a single box rc40, i rarely hear it over the engine noise unless both my windows are open

I think poor sound proofing is a large cause of the boom and reverberation you get in the cabin.

I do agree though, a lot of the mini exhausts are not performance oriented, so are larger than necessary, creating excessive noise.

Noise can be reduced by more baffle boxes or more soundproofing. Extra weight either way, but i'd go with a twin box maniflow if it was my choice

The fact the silencer is straight through is the culpret for most of the noise.

Me personally when I'm done will have the turbo, a sports cat, a mid section and the rear box, all in 2 1/4" Will be interesting to see how loud that is at full bore.

Colin so you recon the side exits don't reach the same db's. Thinking about it modern systems have loads of bends.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

i used the same exhaust silencer i have on the turbo now on a 998 i once had (bike can) and i could hardly hear it. and thats all i had. plus there are no bends in it at all. but its quiet, produces a very nice sound, and seems to give me great power output.

60bhp stage 2 kit 998 N/A
133lbps / 140bhp 9psi (moderate mods)

Why would you choose to run a cat Colin..?

Question being after reading Dave Walkers column in this months Track Driver Mag. He claims that they are the work of the devil..

So hence the question..?

Si

I drill holes in everything..!

1 3/4 RC40's are'nt loud but at what sort of power output do they become restrictive?

one day boost will be mine!

i have no silencer just 2" straight through and its not that loud, the sccr box is much louder

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Call me daft, but imo a 1.75" rc40 will do for any N/A application, because thats pretty much all that goes into the engine, so the exhaust should be capable of taking it away. I can see why a 2" bore is suggested for turbo use though.

Fit a rotary muffler :)

In the 13's at last!.. Just

Sorry if the question sounded out of sorts. Just an honest question.

Dealing with the DVLA resonantly about vehicle taxation and emissions I was informed that they relate to engine year of production, not chassis year of manufacture.

My car does not have to run one and the taxation class will not change also. This is what the DVLA are after in the first place money.

Walker was referring to actual making them work, and finding that they are very hard things to make work as intended or infact at all.

Never mind the costs of production and harm it does to the environment in production.

They end up doing more harm than good, having to get them up to temperature in a short space of time, Running the engine rich at start up and then keeping it at the correct core temp. Ends up burning more fuel in the first place.

Anyway these are the ramblings of a night worker. So this was my interest in you fitting one to your motor and making it work.

Re: - Mini exhausts I rang a exhaust manufacture direct told them all about the engine spec and car application, and he made one to suit.

And Yep its works very well.

Correct db for competition / road use and produces the right figures on the rollers to.

Si

On 31st May, 2011 Sprocket said:

On 30th May, 2011 Si P said:
Why would you choose to run a cat Colin..?

Question being after reading Dave Walkers column in this months Track Driver Mag. He claims that they are the work of the devil..

So hence the question..?

Si

Since you don't really know the context in which Dave meant his comment, it is easy to make assumptions.

Consider that BTTC and WRC all have to have a cat fitted, and while yes, they might release an amount more power, I don't see them being 'The devils work'. Its vehicle construction and use legislation.

One thing I recon Walker might be spouting off about is the that his tailpipe lambda readings will be all to cock.

I don't agree with those who remove a cat from a car that should have one, and then find a 'friendly' MOT man. Its not the MOT man these people should worry about, its the VOSA man. Fit a quality sports cat (£200+), not a £60 ebay special.

My car should have a cat, so a cat will go back on. Simples

You live your life by values. For me, if refitting the cat means I'm doing a little bit for the better, however minute it may be, I'll be happy knowing that its right

Edited by Si P on 1st Jun, 2011.

I drill holes in everything..!

You are all missing quite an important fact here.

Pea-shooters are quiet as they are restrictive, and cars with them fitted have low power, and low revs, meaning less exhaust gasses and a quieter drive.

Once you start modifing to get more power, you are expecting any scilence to do more work (bigger bang, more nosie). I would think that sound proofing on the boot floor would be a good start, the only other way is to fit a bigger scilencer, not easy in the space available, but you could be imaginative!

On the subject of Cats, there is no point fitting one IMO. You're never going to save the world fitting one to a car you hardly use. And when you come to sort the fuelling, it'll always be a compronise between power and not destroying the Cat.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I totally agree with the second statement. But my understanding was that 12.5:1 would quickly destroy a Cat and you need to be closer to sticcho to ensure it worked.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I have a single DTM silencer on my car, the rest of the system is 2". It was really loud when the car was NA but I thought it sounded fantastic. I did twice get asked when I was going to get my car fixed by people at work, I guess a cammy engine with a loud exhaust sounds broken to some people! The other issue with it was that it would set car alarms off, including the same Transit on my road everyday. I was also told by one of my neighbours that they didn't need an alarm as they got woken up at 7:20 everyday by my car.

Once I fitted the turbo engine I was quite disappointed how quiet it was and also that it's lost the rasp it used to have. I might consider running no silencer.

On the subject of cats, I also dislike them. I have removed them on all but one of my cars, I tried to get my 91 built but 92 registered Audi through an MOT without them but the tester wouldn't pass it. I spoke to VOSA and they confirmed that if the engine was built in 91 (which I had a letter to prove) they should pass it. I ended up getting a cat fitted which was very expensive but the tester is a good friend of my friend's dad and he really wasn't happy with it so I gave in.

And what car do you know runs under load at 14.7:1AFR?

The cat is happy with 13.2:1 to 12.5:1 (peak torque) fueling under load. Thats not to say it is efficient at that.

The hydrocarbon content really fucks them up

Stop using logic, you make me look like a dick!

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Wil that understand the concept, I'm just not convinced that they need to be that loud to make the power your average tuned mini does. Just a debate, I presumed that the double rear mig style silencer would greatly reduce the noise however I bet the silencer design also has a lot to do with it, output pipe size, constructions etc.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I guess it all boils down to the fact that if Maniflow sold quiet exhausts, they wouldn't sell any exhausts; if you see what I mean.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Mm see what you mean, so too many chavs buy minis :)

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I think Wil is spot on, demand drives the product.

However in defence of Maniflow (who make decent quality stuff IMO) I am sure that if you rang up and asked them to make you a quieter but still free flowing system, they could.