Stock exhaust max power ?

[JP]

Defo 5pot rumble

[Cottis]

God I miss the 5 pot rumble from my KV CQ's both with stock exhausts. When the exhaust finally gave up beyond repair on one of them I fitted a powerflow ss exhaust and it was awful. I understand why you want to go back to stock but with a turbo you never get the full soundtrack that you would from a n/a KV 5 pot. Don't think I have ever driven such a beautifully smooth and silky engine. Gutless and thirsty but lovely in every other way.

Love my miltek on the S2 but reckon I would tire of it pretty quick if it was a daily.

[|Maku|]

At one point when mine was a daily for 35k miles of its life the drone and everything bugged me. I wanted what you are seeking smooth quiet and a nice wot roar without giving you tinnitus.

Played around with loads of combo's finding a nice compromise in the end. Ran a straight through 3" system from turbo back with no silencers literally a 3" tube and mounted the stock backbox to it.

Made 574hp like that and was bliss to drive as a daily, nice rumble when openedpup, no droning and quiet enough you could have a normal conversation wuth your passengers.

Yes I know that this sort of combo - bigger diameter pipe with stock backbox - is a neat solution. I have used it in the past as well but according to this (http://www.exhaustvideos.com/faq/how...-pipe-diameter) article You have left a healthy amount of horses on the table. How accurate this exhaust tabel is, Im not completely convinced.

[|Maku|]

Also I think You have read this:

Jay Kavanaugh, a turbosystems engineer at Garret, responding to a thread on www.impreza.net regarding exhaust design and exhaust theory:
Again, less pressure downstream of the turbine is goodness. This approach minimizes the time-to-boost (maximizes boost response) and will improve engine VE throughout the rev range.
As for 2.5" vs. 3.0", the “best” turboback exhaust depends on the amount of flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power level won’t get you much, if anything, other than a louder exhaust note. 300 hp and you’re definitely suboptimal with 2.5". For 400-450 hp, even 3" is on the small side.”

[|Maku|]

And this (Supersprint 70 mm):

AUDI Coupè S2 Quattro 2.2i Turbo (230 Hp) ' 90 ->

OEM
Claimed data:
Horsepower 230Hp at 5900 rev/min
Torque 350 Nm at 1950 rev/min
Actual data:
Horsepower 239,1 Hp at 6415 rev/min
Torque 345,6 Nm at 2850 rev/min.

Supersprint
- Downpipe 764011
- Centre 765103
- Rear muffler 765104
- Endpipe 765116
Actual data
Horsepower 250,3 Hp at 6390 rev/min
Torque 374,1 Nm at 3150 rev/min.


AUDI 80 B4 (Sedan+ Avant) 2.2i S2 Turbo Quattro (230 Hp)

OEM
Claimed data:
Horsepower 230 Hp at 5900 rev/min
Torque 350 Nm at 1950 rev/min
Actual data:
Horsepower 239 Hp at 6350 rev/min
Torque 353.5 Nm at 2820 rev/min

Supersprint
Kit of pipes for turbo charger + Kat. 764021
Centre exhaust 764003
Rear exhaust 764006
Actual data:
Horsepower 250 Hp at 5760 rev/min
Torque 403.5 Nm at 2590 rev/min

[newsh]

Agree with JP, 3" system with stock or quieter back box is the way to go

My 034 system was a nightmare to drive below 3k RPM, so boomy, to the extent I was always driving too fast to get above the boom and in danger of losing my license Changing to a quieter back box sorted it. Best sounding quattro is a ur 10v with centre box removed IMHO

[Error404]

Andy if I were you I would add an additional removable silencer, and also have a straight pipe made up to suit - then you have have both options without changing the whole system over

[Rusty]

What has been described is basically my system as was, which I described early on and it works just fine

You can run a more restrictive back box because the exhaust gas has cooled and become denser by that point, so mass flow rate can be maintained through a smaller pipe.

What about getting something like an old Milltek back box and getting it V banded in place of the current rear box, so that you can swap it in / out easy like.

[|Maku|]

You can run a more restrictive back box because the exhaust gas has cooled and become denser by that point, so mass flow rate can be maintained through a smaller pipe.

Silencer Design.
- Straight through or reverse flow silencers are best.
A well designed silencer, placed to the rear of the car won’t drop power by anymore that 3-5%. The closer to the engine they are fitted, the more flow restricting occurs and the more power is lost.
Straight through or reverse flow silencers are the best for power applications. Straight through provides the best sound deadening and are good for turbo cars. However, on NA cars two silencers or a silencer and a resonator must be used to stop popping occurring on overrun. The quietest silencers have an open resonating chamber in the middle.
Reverse flow silencers are different and don’t contain any sound deadening materials. This makes them lighter, but poorly designed ones are loud and cause power loss. The main advantage is that they are good at suppressing popping when you lift off the throttle.

[macspring]

My tuppence, for what it worth.

Started with an ABY standard with and ABY exhaust - grand.

Homefried it - well pleased.

Then cat bypass pipes - bit keener to rev out. No biggy though.

Miltek - louder but no faster that I could tell. Not as stealthy though.

Changed to a custom 3" system with boxes that were not really big enough to silence the 3' pipe, very loud. Embarrassing to drive. Everyone knew you were about and what your foot was doing on the accelerator, as it was like a volume knob. An US 3' down pipe which fouled the subframe. The 3"icy system was a waste of money with hindsight.

Put back on an oem system, and RS2 down pipe. cat bypass pipes. Car was lovely and quiet, stealthy and no slower.

Put the cats back in for an MOT, no discernible power difference around town.

Took the cats off as they weren't mine, and again no difference. Small blowing where one of the small pipe with a sleeve goes two into one under the handbrake, was causing the exhaust to sound like it was broken / appear a bit banger like.

Took the sleeve off, fettled i, then refitted it with exhaust paste and copper grease to make it squeeze the two exhaust pipe ends properly. Car is now silent and sound perfect, is discrete, does not attract attention, and is no slower.

After going through all of the above, I now believe I should have left the exhaust system as it was, with the exception of the RS2 down pipe, and also the cat bypass pipes, and I would have saved myself close to €2k, if I'm honest, and a lot of time grief and disappointment.

One would be much better off buying a Recaro type drivers seat, and a RS2 hybrid turbo / matching chip for the same money, and I feel it would be much better use of one's money, and a lot less waste of time and grief.

The above is just my own experiences, and is not necessarily correct / relevant for others.

Best wishes.

[andyg plym]

http://www.s2forum.com/forum/showthread.php?t=59115&highlight=Exhaust

See me exhaust as above, got a 3inch dp too

[|Maku|]

Actually You cant say that 3" system is always worse. Sometimes You hardly ever notice the difference between 3" and stock one. You just have to use good mufflers. I had Simons cat-back system on S4 B5 and it was a blast to drive - no drone what so ever.

[Ian Simmonds]

http://www.s2forum.com/forum/showthr...hlight=Exhaust

See me exhaust as above, got a 3inch dp too

Are you going soft on us Andy? I can't believe I'm reading this thread! You of all people...

PS. that 3" turbo back Miltek you sold me is just fine, In fact, I'm taking it for a run out in about 10 minutes...

[andyg plym]

Are you going soft on us Andy? I can't believe I'm reading this thread! You of all people...

PS. that 3" turbo back Miltek you sold me is just fine, In fact, I'm taking it for a run out in about 10 minutes...

Hark at you Ian lol !!

Must be getting old mate maybe your right !

I reiterate though that the 3 inch won't be sold , just fancy a breather......

I want to hear that 5 pot rumble again but at every day speeds.

Glad your enjoying the miltek mate

[andy j]

At one point when mine was a daily for 35k miles of its life the drone and everything bugged me. I wanted what you are seeking smooth quiet and a nice wot roar without giving you tinnitus.

Played around with loads of combo's finding a nice compromise in the end. Ran a straight through 3" system from turbo back with no silencers literally a 3" tube and mounted the stock backbox to it.

Made 574hp like that and was bliss to drive as a daily, nice rumble when openedpup, no droning and quiet enough you could have a normal conversation wuth your passengers.

Sorry for dragging up an old post. I'm starting to get bits together for my 3" exhaust and like the sound of using the standard backbox. What i was wondering is do i reduce the pipe size down just before the back box or would i have to cut a 3" hole on the inlet of the standard backbox for this set up to work?