chawkins2001

I am going to possibly get a custom exhaust made and have already purchased the mufflers and tips which have 3" inlets. Will doing my whole exhaust after the primaries all the way in 3" cause me to loose low end torque and HP. Right now I am making stock power but have a eurocharged 180mm and LET tune waiting to go in.

Aleksander, I know you want this route for a while man, maybe you could chime in bro

chiromikey

you will definitely lose low end tq although it may not be too bad since you're leaving the largest exhaust restriction after the manifolds in place (primary cats). it will be up to you if you can live with the trade off of possibly making it up on the upper end hp.

shardul

iTrader: (1)

I like low end torque, because majority of the time you are driving you are in the low to mid range rpms, so loosing that torque is something I would not want.

jangy

Mine is cut from the primaries back and I love it with the tune. Agreed that you lose low end, but BARELY and the top end gain is large (in comparison). Before, it shifted much slower and now the taq hits the limiter much harder. I would NOT do it on a non-modded car unless you just like the sound which is also minimal. Gutting the mufflers is the only way for that.

Timeless

Do you also lose low end torque deleting just the resonator or just the secondary cats? Or is it when you delete both?

chawkins2001

after reading this I may just get the tapered pipe going into the primary cat opened up like Vadim suggested and eliminate my resonators. My muffler setup is going to be VERY aggressive so I am not worried about it still been quiet. Do you guys think from where I run the 3" piping to replace the resonator, if I continue that all the way out the back to the mufflers and tips I will still loose low end torque?

shardul

iTrader: (1)

hard to tell. the stock system is 2.75". in some areas of the system the piping is reduced to a diameter smaller than 2.75. So if you go with a 3" mandrell bend piping there will be a reduction in torque. also remember the new mufflers will be more free flowing than the stock amg mufflers.

jangy

Secondary cats. the resonator does little (IMO). Also, there are at least 3 pinch points in the OEM pipes. If replaced by 3" tubing that also does it.

jangy

resonator back, there is little resistance. It hionestly doesn't matter what you do there. The drop is all around the primary and secondary cats.

jangy

+1, well put. The mufflers do not matter. Case in point, the gutted ones that we have on this board. It is all sound. Straight pipes instead of our mufflers makes little difference in the psi at the motor.

aleksandar1099

Hey buddy!

I didn't notice a difference in low end torque with the system I had on my car. It was a 3" from the stock manifold, no cats, no resonator, with cutouts, to stock mufflers, and it sounded AWESOME! Loud, but no drone inside the cabin.

here is a vid to the exhaust sound....
http://www.youtube.com/watch?v=Q3zk6...e=channel_page

Hope this helps...
-Aleks

jangy

Agreed, even by a waffler.......

aleksandar1099

..... and I forgot that you are getting new mufflers too! It is going to be beastly loud after that....

check out my video when I had 3" piping and magnaflow mufflers...
http://www.youtube.com/watch?v=vHDG3...eature=channel
.... and yes it scares all of the children and old ladies when I drove by!

...or just go all out and get cutouts....

http://www.youtube.com/watch?v=_ImkO...eature=channel


I love exhausts!!!

shardul

iTrader: (1)

hey aleks

in the above mentioned video that you posted did you incorporate a x pipe any where or was it just straight pipes till the muffler.

chawkins2001

Aww, no you have my thinking to go 3" again. I am definitely going to get rid of the bottle neck though before the primary cat and then run 3" from the secondary cats all the way back. BTW, I went with Magnaflow magnapacs as my mufflers of choice

MRAMG1

The loss of tq is MAINLY on NA motors do to a lack of GOOD scavenging on the lower rpm side as the larger piping does not show as strong as a pulse. Since your motor is FI there really is NO worry here. As was mentioned above, the loss is negligable. Actually I would LOVE to see a before and after dyno showing this loss on any FI motor

I know mine didn't, although it was not an E55. But again, an engine is an engine as the physic's are ALL the same.

Good luck with whatever you decide on

See yeah

blackbenzz

So what if you lose some low end torque? Modded 55 have gobs of it anyway!

chawkins2001

when I get my pulley on and LET tunes it, I am sure they will make it up in the tune

TVT_DESIGN

We put down 595 RWTQ with a full 3" exhaust. No loss of low end torque at all.

bassn_07

...what were the rwhp #'s?

shardul

iTrader: (1)

Was an x pipe installed anywhere in the system?

chiromikey

our cars can definitely lose tq with (improperly) increase flow. i don't have dyno data but i do have REAL performance data from 60ft measurements on my timeslips that prove the loss of tq.

MRAMG1

Okay, so le't see them please.

I really have NO clue how any FI motor could/would loose power on increasing the exhaust size? Espically with a stock cat that acts like a choke to begin with.

Mikey I know you are the king of the strip, but I don't feel that a timeslip could/would show the SMALL loss, if any, in TQ. WAY too many variables as you are aweare of at the track. I think you will agree that you are NOT in the 2000-3000 rpm range for the entire 60' time, yes?

Look at this way, IF, and I use the word IF, you lost 30 lb/ft at 2000 rpm, how would this show up on the time slip as you are only at 2000 rpm for less than 1/10 of a second? And on the flip side the gain above 5000 rpm, lets say 10 HP for the sake of argument would MORE than make up for it, as you would be in this range for about 10 seconds.

Oh well, its safe to say that we will again agree to disagree.

Good luck and see yeah

chawkins2001

X pipes suck, H pipes are the way to go. Coming from the cobra world, H's are way deeper and produce more low end tq. X's are raspier and produce more top end HP.

I can't wait for you guys to hear my new setup. After reading all the posts in this thread, I will go 3" from the primaries back with a H pipe instead of an x. I will also eliminate the bottle neck before the primary cat and basically run resonators as mufflers

chiromikey

the only restrictions in my exhaust are 200cell count high flow cats in the secondary position and the stock mufflers. by just removing the cats and replacing them with straight pipes i went from 1.68-1.69 60ft times to 1.74-1.76. i was willing to give up a tad on the bottom because i expected to gain mph up top but that didn't happen. i was in a frenzy because, as you are aware, that just didn't make sense with what was supposed to happen. not only did i lose very bottom end tq, but tq through the midrange. i'm a firm disbeliever in butt dynos (even more so than real ones) but passing cars was the biggest disappointment. my car no longer possessed that violent kick when passing cars on the freeway. after trying to troubleshoot with wayne (let) we decided to put the cats back and the beast was back.

if you really need me to scan and post timeslips tonight i will but i've got my launch and 1/4mile runs down cold and can run 60ft times within a tenth and et's within a few tenths every time. because of this, it's easy for me to understand when something isn't performing and opening up exhaust too much on my car just doesn't work.

i'm smart enough to know after driving several different amg's at famoso that each car does respond a bit differently to similar mods so this could be just the way my car behaves. i do know that there are people from this board that have noticed the same loss of tq after putting on a more free flowing exhaust such as the eisenman race set up.