What is the purpose of a back box? - Alfa Romeo Forum
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(Post Link) post #1 of 10 Old 30-08-13 Thread Starter
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What is the purpose of a back box?

Looking to upgrade the exhaust on my Giuletta 1.4 TB soon, the long term plan is to go for the full system and work something out for a modified CAT that would still allow me to pass the MOT (or maybe move the cat in the centre pipe so that it is easily installed/removed pre/post MOT,but this is another story ) but for now, I'll start wit the middle pipe and back end.
What I haven't work out as yet, is if the back box works only as a silencer or it does have some use on pressure gasses which, I understand are needed although not as much on a turbo engine.

Sound wise I'm looking for a deep burple with the odd pop rather than a raspy loud scream, and it is a must than I don't loose any torque. I know not to expect much in terms of bhp gains.

Thanks in advance

2010 Giulietta 1.4 TB MA Ghiaccio White: Blistein B12 kit + Ragazzon concentric exhaust+ Cadamuro spoiler+ Custom made air cone filter + ProAlfa FMIC + ProAlfa Remap 190bhp / 260 ft/lb + ProAlfa short shifter+ Spacers all around
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Hello. This may or may not be helpful, because after all a 1.4TB and a 3.2V6 are completely different beasts but my new Wizard system is 'just' a back box... https://www.alfaowner.com/Forum/alfa-...ty-wallet.html

The centre silencer is no more, the rear box - the clever bit - is half the size of the standard lump that's normally there. The sound is simply epic. Having said that, with all the acoustics at the rear you're almost 'leaving the sound behind' with very little reverb in the cabin itself. And yes it backfires, pops and rumbles on downshift too. Torque is very much improved but that's likely to be more to do with the EL front pipes.

Good luck with whatever you decide to do.
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(Post Link) post #3 of 10 Old 01-09-13 Thread Starter
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If Wizard can make the MA engine sounds like a V6 I'll love them forever!

As you said, the 2 engine and sounds are completely different, but, good to see that you are happy with the Wizard set up as I'm keen to get the job done at Autolusso as well
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We did one for a Mito QV a couple of months back and it sounds great, if anything slightly wilder than the old 1.4 turbo 155bhp engine that was first in the Mito. It doesn't sound like a V6 but it sounds smooth and high pitched like an old group B rally car, only with the volume turned down. Lots of pops and cracks
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(Post Link) post #5 of 10 Old 01-09-13 Thread Starter
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Cheers,

From the signature I guess you got it from Ned? Was it you that had the cat re designed to cope with the new turbo?
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I work for Autolusso in the used parts dept, and also deal with the Wizard exhaust enquiries/sales, Ned is the owner and you will mostly find him running the workshop.

We modify the original cats on the Mito 155TB to make them flow better, and as well as that we can supply a complete new exhaust from the cat all the way back to the tailpipes in a much larger diameter, to freely flow upto 250bhp. The Mito QV 170bhp is similar, but I've not seen the cat for this engine in the Giulietta yet, so it could be different. Next time we have one in I will have to take a look at the original exhaust system and see how it can be improved. I'd love to see what we could get out of a 1750, I reckon with a bigger turbo, intercooler and better exhaust, 300bhp should be easy.
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(Post Link) post #7 of 10 Old 01-09-13 Thread Starter
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Very good to know! I was telling Ned that I'll be in touch end of this month for more info.
But, since you are here

The idea is to go with a full system, either in one go or in stages, depending on the cost. I was looking at either leave the cat for now and modify later or move the cat to the centre pipe so that it can be easily removed post MOT, I had a similar set up on a previous car and worked a treat. I understand that the cat in the G is right by the engine and, it would be a pain to swap over. Would this be at all possible? I would be happy to provide the car as a ginny pig and provide feedback and undergo tests if needed, what I need to work out is how to make my way back home if I leave the car with you.

Sound wise, I've owned very loud jap cars but, I don't think this will suit an Alfa, it is also a family car so it cant be bonkers.

To give you an idea, this is the video that first got me started alfa romeo giulietta exhaust - Bing Video's ( not like this wizard exhaust - Bing Video's )

Power wise, I know that I can except more that 10/15bhp but, as stated before, torque is more important at this stage.
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Very good to know! I was telling Ned that I'll be in touch end of this month for more info.
But, since you are here
And I get commission. Right?...
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What are benefits of going for a full system? I have a wizrd cat back, will i see improvements if I go for manifold/sports cat? How will it affect back pressure?
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(Post Link) post #10 of 10 Old 21-09-13 Thread Starter
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For what I've been reading (and I might be wrong)
Sport cats are no more than half restricted while decat let the full flow of the gasses out and the manifold will increase this therefore increase performances. Bhp wouldn't increase by much but, on my old V6 I felt a better response on acceleration. Not yet sure of the effects on a turbo engine
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