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Offline stuntman

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Do I REALLY need exhaust boxes?
« on: February 06, 2010, 19:31:52 »
Well I'm just finishing off my Mazda 3.5 turbo intercooled engine install.

Now it's loud, and I mean loud, my main question is do I really need boxes in the exhaust sytem, I mean for back pressure, or should there be sufficiant back pressure due to the nature of a TDI? I'm not bothered about the noise of the truck, I quite like it and I'm in the middle of a disagreement with my fat Irish neighbour, so I don't mind cracking it over at 0600 mon-fri :)

I just want to make sure that I'm not loosing masses of power by leaving out the back boxes, I don't mind about losing a few.

Regards

Andi
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Offline Saffy

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Re: Do I REALLY need exhaust boxes?
« Reply #1 on: February 07, 2010, 08:32:58 »
From what I gather from previous posts on here is that diesel do not need back pressure beyond the turbo, so exiting after the turbo the gases are best expelled in an non restrictive method as possible (for performance).
Why escalated bad feeling with neighbour? Why mess around like a queen by seeking pleasure in waking him up at 6am? Why not fit decent exhaust silencers to the system and feed the tail pipe into his letter box and silently ensure he doesn't wake up at 6am or ever again? As sure as egg are eggs if you actively participate in a vendetta the little acts such as making a noise have a habit escalating till real bad things happen so a pre-emptive ultimate attack will save time and he is after all just a "fat irish".  
« Last Edit: February 07, 2010, 08:35:12 by Saffy »
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Offline hairyasswelder

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Re: Do I REALLY need exhaust boxes?
« Reply #2 on: February 07, 2010, 11:13:52 »
Dunno, but I would fit one for MOT purposes and for peace of mind that you dont wake the other half,
Fit the centre box and have a straight through side exit  :lol: :lol: :lol: :lol:

I done the same on the V8 and get comments all the time...... my dad wants to make a CD with track 1 @ tickover, track 2 @ 2000 rpm etc...  :lol: :lol: :lol:
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Re: Do I REALLY need exhaust boxes?
« Reply #3 on: February 07, 2010, 12:13:33 »
Straight through - I have on a Td5 90 and have passed MOT's no problem.
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Offline disco2 td5

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Re: Do I REALLY need exhaust boxes?
« Reply #4 on: February 07, 2010, 14:30:12 »
on my discotd5 i have a center box removal pipe and a side exit pipe both with no silencers so its quite noisey sounds great at low rpm but gets annoying when ur sat on the motoway for over about a hour so fit none they sound great lol ive never had troble of the men in blue either mot man says its loud but passes and advises on it
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Offline Tiki Al

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Re: Do I REALLY need exhaust boxes?
« Reply #5 on: February 07, 2010, 16:40:59 »
LOUD PIPES SAVE LIVES  :twisted:
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Offline Dave K

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Re: Do I REALLY need exhaust boxes?
« Reply #6 on: February 07, 2010, 16:43:59 »
I've got a straight thro' centre pipe & a small back box.
Sounds great, especially in Continental tunnels :dance:
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Offline JIMBOBLY

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Re: Do I REALLY need exhaust boxes?
« Reply #7 on: February 08, 2010, 20:32:46 »
Quote from: Tiki Al on February 07, 2010, 16:40:59
LOUD PIPES SAVE LIVES  :twisted:
that is very true,they can here you comin,weather you in a 20,30 or a 40mph limit,ive took this route,purely for the safety of others,not for the noise, :lol:(YEAH RIGHT) :lol:
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Offline richo

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Re: Do I REALLY need exhaust boxes?
« Reply #8 on: February 21, 2010, 09:37:12 »
I'm only running one back box now and am very pleased
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Offline Saffy

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Re: Do I REALLY need exhaust boxes?
« Reply #9 on: February 21, 2010, 12:19:08 »
I just got back box on 110csw tdi, no noticeable difference to drive, increase in noise level is only noticeable when driving roads flanked by wall/hedge row with passenger side windows open - sounds like defective blowing exhaust. A tuned td5 with only back box fitted has a nice growling note.
« Last Edit: February 21, 2010, 12:21:30 by Saffy »
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Offline discosteveo

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Re: Do I REALLY need exhaust boxes?
« Reply #10 on: February 21, 2010, 16:07:32 »
i have a disco 300 tdi with 60mm tube straight through no cat etc, side exit sounds good, disappointingly quiet though, insa turbo tyres are noisier at 60mph

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Offline garetharcher

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Re: Do I REALLY need exhaust boxes?
« Reply #11 on: February 21, 2010, 23:08:01 »
Ive got a 300tdi 90 with a straight through and that rours. Feels like its freeier up top of the rev range i.e. going from 50 to 65 feels a lot quicker. could be my mind but its deffo better. But its also got fuel pump tweeked and all the others! Give it a go with both and see which is more comfy!
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Offline Range Rover Blues

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Re: Do I REALLY need exhaust boxes?
« Reply #12 on: February 22, 2010, 00:42:19 »
They sound really great, for a couple of weeks!

I've fitted big/straight through pipes to a couple of cars and ended up wishing I hadn't, or removing them.  Whilst they are great for tooling around town, late at night they make you sound like a nob and on a long run they get tiring.

It's a medically proven fac t that low, droning noises will make you fall asleep at the wheel!

So the double S system on my LSE is as loud as I like, when it's cruising it's quiet unless it's dragging the 'van, then on long journeys it gets a bit tiresome.

I had a TDi single pipe system on Blue and I got sick of that too.


But that said, if it's a turbo diesel then you need to let the gas out as easily as possible, it's done it's job and it's energy is spent so any restriction in gas flow will effect performance.
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Offline topless matt

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Re: Do I REALLY need exhaust boxes?
« Reply #13 on: February 22, 2010, 06:33:41 »
Quote
But that said, if it's a turbo diesel then you need to let the gas out as easily as possible, it's done it's job and it's energy is spent so any restriction in gas flow will effect performance

This only aplies for the first meter or so of the exhaust pipe, after that, it makes no real difference having different pipe sizes.

i have a straight through side exit on the 90 with the fuel pump tweaked, sounds really good and i havnt got tired of it yet  :lol:
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Offline V8MoneyPit

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Re: Do I REALLY need exhaust boxes?
« Reply #14 on: February 22, 2010, 17:05:54 »
One thing to bear in mind is that some events might not let you run with an excessively loud exhaust. I noticed a P&P site the other day that had a limit of 98db at 0.5m and 3/4 max revs. This is not very loud.
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Offline stuntman

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Re: Do I REALLY need exhaust boxes?
« Reply #15 on: February 22, 2010, 21:11:22 »
Sorry I've been away chaps, but I've been running it with a striaght through 1m 3" exhaust pipe.

My other half decided that it needed an exhaust, so I've built twin stacks with tractor flaps on the tops, and to be honest it's cool, very cool, in fact ice cool.

The engine is noisier than the exhaust but then again I have no sound deadening YET (there will be) but lets just say when I was gently cruising on the M1 yesterday I was up the chuff of an M3 in the outside lane without realising it, I'm by no means a careless or in experienced driver (I'm an automotive stuntman aswell as equine) and I have to admit the Mazda engine that I've dropped in is a monster.

I'm very happy  :dance:
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Offline V8MoneyPit

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Re: Do I REALLY need exhaust boxes?
« Reply #16 on: February 23, 2010, 10:25:36 »
This thread is useless without pictures..... please!!
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Offline Saffy

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Re: Do I REALLY need exhaust boxes?
« Reply #17 on: February 23, 2010, 10:41:16 »
Quote from: V8MoneyPit on February 23, 2010, 10:25:36
This thread is useless without pictures..... please!!

pictures of noise ?
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Offline V8MoneyPit

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Re: Do I REALLY need exhaust boxes?
« Reply #18 on: February 23, 2010, 11:55:12 »
Stack exhaust pipes of course  :roll:
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Offline Saffy

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Re: Do I REALLY need exhaust boxes?
« Reply #19 on: February 23, 2010, 11:58:40 »
Quote from: V8MoneyPit on February 23, 2010, 11:55:12
Stack exhaust pipes of course  :roll:

doh. There is a cab 90 running around here with twin stacks and a v8 - it's LOUD. If I do the nav-ex on Sunday he might be there and I will take photos.
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Offline V8MoneyPit

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Re: Do I REALLY need exhaust boxes?
« Reply #20 on: February 23, 2010, 12:38:03 »
Quote from: Saffy on February 23, 2010, 11:58:40
Quote from: V8MoneyPit on February 23, 2010, 11:55:12
Stack exhaust pipes of course  :roll:

doh. There is a cab 90 running around here with twin stacks and a v8 - it's LOUD. If I do the nav-ex on Sunday he might be there and I will take photos.

I always thought they would look good on my Morris 1000 van, but never got round to doing it before it was sold. Not sure they would have sounded quite as good as a V8, or Andi's Mazda 3.5, though  :lol:
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Offline Saffy

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Re: Do I REALLY need exhaust boxes?
« Reply #21 on: February 23, 2010, 13:40:35 »
Quote from: V8MoneyPit on February 23, 2010, 12:38:03

I always thought they would look good on my Morris 1000 van, but never got round to doing it before it was sold. Not sure they would have sounded quite as good as a V8, or Andi's Mazda 3.5, though  :lol:

The original pea-shooter got a uniquely british sound though, that and the A-series clutch whine on deacceleration.
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Offline 110crewcab

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Re: Do I REALLY need exhaust boxes?
« Reply #22 on: February 23, 2010, 18:18:05 »
hi i ran a mazda sl35t a number of years back and wow what an engine, best diesel ive ever driven. i had a straight through exhaust pipe on that not a problem and not to loud, i also run one now on my challenge truck with vertical stack no silencer and that just sounds perfect
drop the box and drop the pedal, see the jaws drop :lol:
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