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Discussion Starter #1 (Edited)
Right so you may know I had a S/S straight through Catback system from Torque Exhausts with 2 centre silencers and reduced width 2.25" centre pipe.

That system really pushed up my low end torque by a hell of a lot using increased back pressure, but this stiffled my high end to the point that it was best to change up at 5000 revs as the torque would drop off past that. Liveable with, great for town driving, but gave little increase in peak power and high speed efficiency. Also, the silencing wasn't really up to scratch so I had an annoying drone around 2,500 revs that used to give me a headache after about 20-30 mins of town driving :(

So after getting a few different opinions I decided to get a Vortex Centre silencer direct from Vortex Exhausts in Grays, Essex. In the end, they built a whole new straight through Catback system, 2.25" pipe, one Vortex in the Centre, more 2.25" pipe, then an ordinary centre silencer next to the fuel tank, then the Y joint, 2" pipes and a pair of smaller silencers in front of the stock Brera tail pipes.

Result?

IT WORKS!! It really does what they claim. The strong low-rev torque achieved on the old catback system has been maintained, and the mid and especially high end torque had gone WAY up. It pulls and pulls at fast motorway speeds now, and throttle response is up throughout the range but particularly at high revs, so peak power is clearly up. MPGs have already gone up about 2 or 3 mpg (10-12%) on the computer; I will need to verify on brim to brim tests but as the map/ECU has not been altered for a year I think we can take it as read that the MPGs have increased.

The Vortex chamber spins the gasses and spits them out at speed, decreasing the back pressure in front of the Vortex dramatically and thus sucking the combustion mixture out, drawing fresh air into the chambers (correct me if I've got the science wrong).

I'm taking the car up to Red Dot in the next couple of weeks to get it Rolling Roaded and tweak the map (suspect the fuel:air mix can now be increased), but I can tell you now torque is up across the range compared to standard, peak power is up a lot, mpgs are up ~10-12% and throttle response is improved further. Takes about 1.5 secs to rev to the red line at idle. Achieves something stupid like 35 MPH in first gear in about 2.5 to 3 secs.

Oh and finally it's QUIET!! They have used good quality silencers, there is absolutely no drone. You can hear an increase in volume at 2500 revs but nothing drastic and no drone. At idle, it's quieter than the previous catback system so a bit more like the original exhaust sound, but it still pulses more like a V6 than a 2.2 I think. When it gets close to 4000 revs the entire system goes totally silent and enters some kind of stealth mode! Great for high speed cruising.

Finally, that crazy whistling sound you hear on the silver Audi TT (on the Youtube video when you search for Vortex Exhaust) is not there. If I rev the engine right up to 6 or 7K and change gears in a tunnel with the windows down, I can hear a slight whistling noise changing pitch, like a turbo-engined car changing gears? That's all, and I quiet like it. I suspect that TT in the Youtube video had little or no silencing after the vortex, and probably had a turbo. May be it had twin Vortex rear boxes instead of rear silencers (I don't know whether there would have been space for this on the TT).

I'm pleased with this. The whole system including custom stainless steel pipes throughout, Vortex chamber, 3 silencers and fitting only cost £100 more than Torque Exhausts charged, which is excellent when you take into account the Vortex chamber alone is supposed to retail at £280 plus VAT. The workmanship looks great, the Y joint in particular looks much better built.

I'm very interested in what the Rolling Road results will be. 2.2 engine, Mangos induction, tweaked Red Dot custom Remap, Stainless Steel Catback with Vortex = ???

I'm pretty sure it will be over the magic 200bhp, but by how much... any guesses?
 

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Discussion Starter #3
Will need someone to do some camera work from the roadside at some point, once I have done this I will upload for you. At the moment my Bella is nice and clean and tucked up in her carpetted garage whilst our other vehicles get filthy from the snow and road grit!
 
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At the moment my Bella is nice and clean and tucked up in her carpetted garage whilst our other vehicles get filthy from the snow and road grit!
:lol:


Your setting it up to be a classic in it's later life, I reckon.


I think the ol' Brera will be a bit of a collectors cars in 15-20 years.

;)
 

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Discussion Starter #5
You may be right there Nev.

She's only done 18K miles in her life and the paintwork is, if anything better looking than it came out of the factory! Runs about 25% more bhp and 20% more mpg than factory. Planning on keeping her for several more years. Suspect she will give the stock Brera 1750 TBi a run for its money they way she is performing! What is the Brera 1750 going to be - 200 or 235bhp? Could beat a 200, maybe not a 235...
 

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Will need someone to do some camera work from the roadside at some point, once I have done this I will upload for you. At the moment my Bella is nice and clean and tucked up in her carpetted garage whilst our other vehicles get filthy from the snow and road grit!
cool, yes the grit n salt really ruins em:(, and hope she's got a duvet n slippers on too.:cool:
 

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Interesting stuff. I know vortex shedding meters etc but I didnt know of vortex style exhausts...
 

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Sounds interesting CF :cool::thumbs:

Piccies when the weather is better :)
 

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Discussion Starter #10
Sounds interesting CF :cool::thumbs:

Piccies when the weather is better :)
Hi mate. There's no piccies to be had as such, there is no cosmetic difference to the car whatsoever, you can only see the work when the car is up on a ramp. If it's up on a ramp at some point I will take a pic...
 

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They have a decent price for the cats on the 156 JTS, not too sure about whether they are specific to that company or not though.
 

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Discussion Starter #14
I believe they make most of their boxes and cats themselves/from their US company. Quality of the boxes is very good - silencing is much better than the boxes I got from Torque exhausts. Hence I'd imagine the quality of the cats is good too. Really seem to know what they are doing, quality of work done seems great.
 

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I would've thought any restriction or change in direction to the exhaust flow would cause it to slow down and heat up the restriction area, thus increasing backpressure. So what's the trick with the little bits in the Vortex exhaust that are supposed to increase exhaust speed?

Does it make sense to summarize N/A exhaust tuning like this:

Bigger bore: low backpressure, slower gas velocity, less low-end torque but more top-end power
Smaller bore: higher backpressure, faster gas velocity, more torque (to a point) but less top-end power

Can you really have less backpressure and faster gas velocity, to get more low-end torque AND top-end power as what the Vortex is supposed to do?
 

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Discussion Starter #17 (Edited)
Bigger bore: low backpressure, slower gas velocity, less low-end torque but more top-end power
Smaller bore: higher backpressure, faster gas velocity, more torque (to a point) but less top-end power

Can you really have less backpressure and faster gas velocity, to get more low-end torque AND top-end power as what the Vortex is supposed to do?
YES! You've sort of hit the nail on the head. My understanding is that you are correct, for a pipe of a fixed diameter. But the Vortex chamber is both bigger in the middle and smaller at the ends, plus it does some complicated thing with spinning the gases in the middle section to speed them up at the back. If they showed us the inside of the chamber I suspect it would seem obvious but then I'm sure people would copy their design.

Daryl, it looks NOTHING like that ebay crap! Vortex UK Performance Stainless Steel Exhausts, Catalytics Converters & Silencers

What you guys do with your cars is up to you, all I know is I'm getting 30 mpg on a fast run out of a petrol Brera :eek: and the dyno confirms that my torque and power have gone up :)
 

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Wonder if it would fit my evil derv beastie :confused:
 
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