Estimated HP gain with an open exhaust???

[SteveKen]

I'm having the resonator and mufflers removed on the car very soon. I'm wondering if anyone else has done this and what difference (aside from sound) it made?

[kismetcapitan]

+1, also interested. Although aren't the biggest gains from open downpipes? I wonder what the power gains would be with fully open pipes?

[ben916]

IIRC, Hy Octane "allegedly" has straight pipes, not sure of the HP gains though, he would be a better source of information!

[Elevens]

I suspect that Straight pipe to the Rear would be impractically Loud, with minor Power gains if any. A properly Tuned Exhaust system (no resonator and no cats) will offer the biggest gains. I am running Milltek Racing Downpipes (No Cats) and there is quite a noticeable difference in throttle response, since the Turbo's spool up much faster. I believe there is a minimum power gain of at least 20-30hp and you can feel it. Oh and I just love the Sound of the Turbo's whistling as they spool up...................................

[Brav]

I removed the resonators, stock mufflers. Not loud by my standard, but nice.. everyone certainly hears me start the car in the morning, and pull up.

[Elevens]

No Resonators, no Mufflers and not Loud?? Hmm... You must have some pretty forgiving neighbors. I have to feather my throttle in the mornings when I leave for work so as not to disturb anyone. I can't Imagine the Drone you must have at highway speeds either, because I get some even with Mufflers. To each his own I guess........................

[repda503]

People definitely hear me roll up to their house and all I have is the resonators cut out. I'm not a big fan of the drone. Does Millteks create drone?

[kismetcapitan]

if tuned for, virtually all engines benefit from straight pipes, *especially* turbocharged engines.

There's a C63 AMG in my condo complex, and that thing has a wild bark to its exhaust note. Turbo engines can never get that loud due to the muffling effect of the turbos. I guess I have a different standard for "loud" - I don't like highway drone. Beyond that, it's never too loud.

[SteveKen]

No Resonators, no Mufflers and not Loud?? Hmm... You must have some pretty forgiving neighbors. I have to feather my throttle in the mornings when I leave for work so as not to disturb anyone. I can't Imagine the Drone you must have at highway speeds either, because I get some even with Mufflers. To each his own I guess........................

To somewhat support the "not loud" argument: I drove the car with no exhaust for about 1500 miles and it was not unbearable or annoying at idle, etc.

Some pretty poor MP4 videos of it are at:

http://www.kendrish.com/galleries/RS6/misc/open_exh/

On the highway, the drone was bad between 55-60 in 6th gear, but other than that...

[hahnmgh63]

I also have the Milltek Race Downpipes (no cats) with the stock SE exhaust and it is slightly louder at idle and low speed than stock but at highway cruising speeds is almost the same as stock until you put your foot in it, and Zero drone. The milltek's are about 1/4" diameter larger than the stock Downpipes so the back of the Milltek's just slide neatly into the stock exaust pipes so a set of Band clamps is all that is needed. Elevens also has replaced his rear exhaust with the Milltek's so they are a little more open and have the extra 1/4" diameter over the stock or SE exhaust. The four Catalytic Converters are definitely your biggest restriction.

[Hy Octane]

Removed the rear mufflers and replaced them with quad straight 3" pipes.. Its loud, not too loud and sounds like a Nascar motor..
The factory system is pretty good as far as flow goes .. however, I did notice a quicker response time and less pedal pressure needed to get off the line..Since you dont have to get into the gas pedal so hard, the noise is mainly when heavy acceleration, like on the fwy's or such. Around town is great. Folks hear you coming but everyone and their brother wants to race you..
HP gains.. dunno. but maybe 10-15..Still, prefer it this way than factory. BTW, Had the work done at LaBree and it was only $400..

[4everRS]

Have you been next to a NASCAR stock car when running?

[Elevens]

^^ I was thinking the Very same thing 4everRS. I go to a few Nascar Races a year (Daytona and Homestead) and If Hy Octane's sounds like a Nascar Motor, then its Loud. The Sprint Cup cars are 850hp with open headers ( Did I say Loud !!). Hy Octane your funny man........................

[kismetcapitan]

Have you been next to a NASCAR stock car when running?

it is painfully deafening!!

[NSU RS6]

This is a funny thread. The original owner of my car (until 01/12), a banker, about 60 years old, told me that he was done starting up/pulling up somewhere and having everyone know he was leaving/arriving. (SE exhaust).

Exhaust note travels farther than you think, especially when the notes are deep.

I like it, but WOT is definitely enough noise for me, especially when I have passengers.

What a puss eh?

[Hy Octane]

It is loud, but I have had it for 5-6 years now and not one complaint..I didnt mean it was as loud as a Nascar motor, but it has the same tone/howl ..

[kismetcapitan]

It is loud, but I have had it for 5-6 years now and not one complaint..I didnt mean it was as loud as a Nascar motor, but it has the same tone/howl ..

your car sounds awesome; it is a template for how I want my car to sound eventually.

btw, are your downpipes and resonators stock?

[na1mt]

I have stock downpipes with all cats removed and a non resonated Milltek exhaust and it is annoying after a while

[kismetcapitan]

I think the one thing to KEEP, are the resonators. Loudness can be very enjoyable, so long as you don't have highway drone.

[peiserg]

ladies and gentlemen,

I did back to back dynos back in the day when I had my milltek race cats and exhaust put on. Almost zero gain. feel free to search on here in my old posts, i'm sure i put in a dyno graph. Sound nice? sure. Worth $5000 power wise? no fawking way. Gains were again (in case you missed it) ALMOST ZERO.

[lswing]

ladies and gentlemen,

I did back to back dynos back in the day when I had my milltek race cats and exhaust put on. Almost zero gain. feel free to search on here in my old posts, i'm sure i put in a dyno graph. Sound nice? sure. Worth $5000 power wise? no fawking way. Gains were again (in case you missed it) ALMOST ZERO.

Of course, you need to adjust the tune to take advantage of the reduced back pressure on the turbos...

[SteveKen]

Anyway... I got the car back on Friday and I'm thinking I probably should have kept the resonators on. It's a bit too unrefined and raw for me now. I've only been in the driver's seat, so I can't attest for how it sounds outside of the car while under any load. At idle, it sounds pretty good an the turbos slice things up and give it an eerie whistle.

My whole reason for the HP gain question is because I'm hoping to get to the dyno this week, primarily to get the delta before and an after 6 speed conversion. Due to scheduling, I couldn't get it done prior to the exhaust delete. I was hoping to have a true before and after comparison in WHP, but now it will be a before and after 6 speed conversion plus exhaust delete.

I expect to see less drivetrain losses through the clutch and 01E but can't attribute it all to this now that the exhaust has changed. Maybe it's negligible though since I'm going to dyno with the stock tune???

[4everRS]

Peiserg, what tune do you have?

[lswing]

Ummm, you need a tune, you will be amazed!

Edit, guessing you've tried one? Looking to compare stock numbers eh?

[SteveKen]

Ummm, you need a tune, you will be amazed!

Edit, guessing you've tried one? Looking to compare stock numbers eh?

I've got a GIAC tune that I'm satisfied with, and yes, I want to just compare the stock numbers.

Toggling the tunes with the flash loader doesn't seem to be an instantaneous switch, so a tune comparison really can't be done during one dyno session. Figured I'd just stick with stock.

[ttboost]

You can only really compare dyno numbers to other RS6's on the same dyno. My car made squat on a Mustang dyno, compared to other members cars here, but made consistantly the same power as other RS6's on this same dyno, obviously...It's fair to say that most tunes add 60-80whp over stock...probably as close as you are gonna get?

[SteveKen]

You can only really compare dyno numbers to other RS6's on the same dyno. My car made squat on a Mustang dyno, compared to other members cars here, but made consistantly the same power as other RS6's on this same dyno, obviously...It's fair to say that most tunes add 60-80whp over stock...probably as close as you are gonna get?

I'm cognizant of this. I'm going back to the same shop that did my original runs before the conversion. It's the only AWD dyno in the Pittsburgh Area Here's the results last year. Hopefully they will improve as expected. Runs are scheduled for this Friday.

http://www.kendrish.com/galleries/RS6/misc/rs6_auto_trans_dyno.JPG

[peiserg]

ive got OC.T and water injection.

i'm assuming unless you guys do a totally custom tune then it wont take advantage of the milltek exhaust. I DID inquire way back when about a more aggressive OCT tune and was told no such luck. HOWEVER, the stratmosphere website (USA dealer for milltek and OCT) sold the exhaust and tune as a package... so one might be lead to beleive the tune was supposed to take advantage?

[SteveKen]

Just got back from the dyno. . .

TQ increase from 334 to 374: +40 lb-ft -> 12.0%

AWHP increase from 323 to 366: +43 HP -> 13.3%

Plot of run 3 of 3: (dyno's printer running out of ink)

http://www.kendrish.com/galleries/RS6/misc/rs6_manual_trans_dyno.JPG

So, how much of this increase is attributed to the open catback exhaust and how much is a result of the drive-train gains via the manual transmission??????

For comparison, I wonder what the data is for the A6 2.7T manual vs. tiptronic?

In my case, it can't all be exhaust, so there's another good reason for the manual conversion.

[lswing]

Interesting details, thanks! I would think it's a combo of the two, very nice to see the extra power, keep it up!

[ttboost]

Is this flashed or stock?

[SteveKen]

Stock ECU

[ttboost]

Yes...very nice gains..my guess is 60% transmission and 40% exhaust...

[SteveKen]

Yes...very nice gains..my guess is 60% transmission and 40% exhaust...

I'd hope to think that it's more trans related and less exhaust based on this:


ladies and gentlemen,

I did back to back dynos back in the day when I had my milltek race cats and exhaust put on. Almost zero gain. feel free to search on here in my old posts, i'm sure i put in a dyno graph. Sound nice? sure. Worth $5000 power wise? no fawking way. Gains were again (in case you missed it) ALMOST ZERO.

I'm coming around to the exhaust, though. I'll try and post up a video of the dyno run.

[hahnmgh63]

No back to back Dyno's but I can say that the boost does come on a couple hundred RPM earlier without the Cats, and seat of the pants say's it pulls harder but some of that may just be the improved transmission shifting. I don't think you'll find it hard to find any race shop say that you won't get an improvement on a Turbo car with less exhaust restriction.

[Brav]

I would never put any type of exhaust on this car with the expectation of a power increase. All for the louder noise-maker.. which is fine by me.

[kismetcapitan]

with turbocharged cars, any removal of backpressure will reduce turbo lag, even if max power gains are minimal/insignificant.

[ttboost]

Yep...air is air...you only get it sooner...with less back pressure...ie..quicker spool...

[SteveKen]

Finally uploaded a video of one of the pulls


http://youtu.be/vuzmf4zY4tM


http://www.youtube.com/watch?v=vuzmf4zY4tM

[lswing]

Nice! Bit raspy with the open pipes, pretty cool though...

[kismetcapitan]

wish my car was black. Sexiest RS6 color, although the Imola Yellow is pretty damned hot as well.