Is going 3" from the primary cats back too much
04-30-2009, 03:24 PM
#26
I also noticed a slight decrease in torque but I don't have number to back it up. At that time I didn't have any cat's and kept my resonator. Though, I am having my car re-tuned and 200 cell cats in place of the primaries...we'll see.
04-30-2009, 03:56 PM
#27
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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 have worked on and owned superchargered cars since the late 80's, and EVERYONE has always responded positively to a larger exhaust.Even KenneBell, Vorteck, B&M, and Lysholm screw all recomended to me to make an exhaust with as LITTLE restircition as posiable on ANY FI motor.
Maybe there is a point of limit return?
It just still doesn't pan out right IMHO
Thanks for the info
See yeah
04-30-2009, 05:22 PM
#28
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No Mikey, you really don't need to post them as I do trust your word, and Wayne's too may I ad. It just doesn't make any sense. I have worked on and owned superchargered cars since the late 80's, and EVERYONE has always responded positively to a larger exhaust.
Even KenneBell, Vorteck, B&M, and Lysholm screw all recomended to me to make an exhaust with as LITTLE restircition as posiable on ANY FI motor.
Maybe there is a point of limit return?
It just still doesn't pan out right IMHO
Thanks for the info
See yeah
. I have worked on and owned superchargered cars since the late 80's, and EVERYONE has always responded positively to a larger exhaust.Even KenneBell, Vorteck, B&M, and Lysholm screw all recomended to me to make an exhaust with as LITTLE restircition as posiable on ANY FI motor.
Maybe there is a point of limit return?
It just still doesn't pan out right IMHO
Thanks for the info
See yeah
04-30-2009, 08:43 PM
#29
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E55, GLS450, GL63, GLE350
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.
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.
If you restrict the flow with pipes that are too small, it will create blockage in the system and your engine will lose power. You may have great off the line torque but after that it will fall on its face.
You also want the exhaust to be as hot as possible. A very hot air mass moves faster than a cooling/cool air mass. Too big and it will slow the velocity down causing the air to cool and move slower and it will hurt your hp.
04-30-2009, 09:29 PM
#31
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honestly torque is the 55s biggest problem off the line and actually i think it might help u win more races since it might reduce tire spin out of the hole on the street tires .especially if the torque curve is coming later .
04-30-2009, 09:45 PM
#32
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This is actually a concern of mine also. I have the Kleemann headers, downpipes (which delete the first set of cats), and there 200cel secondaries all just waiting to be installed. I've already deleted my resonator. I just don't want to lose that low-end rush of torque and power I love. Since I have the 5.5 NA its even more of a concern.....
05-01-2009, 12:58 AM
#33
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It's all about exhaust velocity and flow. Go too big and you kill the exhaust velocity. When you slow the exhaust velocity by going with an exhaust that is too large it hurts your HP. It doesn't matter if your car is NA or blown. If bigger was always better on forced induction engines the exhaust from the factory would be dual 5" pipes but that's not the case at all.
If you restrict the flow with pipes that are too small, it will create blockage in the system and your engine will lose power. You may have great off the line torque but after that it will fall on its face.
You also want the exhaust to be as hot as possible. A very hot air mass moves faster than a cooling/cool air mass. Too big and it will slow the velocity down causing the air to cool and move slower and it will hurt your hp.
If you restrict the flow with pipes that are too small, it will create blockage in the system and your engine will lose power. You may have great off the line torque but after that it will fall on its face.
You also want the exhaust to be as hot as possible. A very hot air mass moves faster than a cooling/cool air mass. Too big and it will slow the velocity down causing the air to cool and move slower and it will hurt your hp.
05-01-2009, 01:01 AM
#34
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tq + traction = great 60ft times and great 60ft times improve et's. with the right tire you don't have to worry about tire spin so i want as much tq as i can get without sacrificing hp.
05-10-2009, 02:49 PM
#35
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Just completed the resonator delete with straight pipes and there is definitely a noticable difference in drone and sound inside and out of the car.
My mufflers and tips go on this week and I will provide you guys with a video clip.
My mufflers and tips go on this week and I will provide you guys with a video clip.
05-10-2009, 04:04 PM
#37
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If the noise is bothering you, should do what I did and get Dynamat sound proofing and install it to the back of your heat shield all the way down the exhaust. Will quiet things up nice inside of cabin and will still keep aggressive sound outside without being annoying to you or anyone inside your car!
05-10-2009, 06:38 PM
#38
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Whatever we're tuning!
If the noise is bothering you, should do what I did and get Dynamat sound proofing and install it to the back of your heat shield all the way down the exhaust. Will quiet things up nice inside of cabin and will still keep aggressive sound outside without being annoying to you or anyone inside your car!
Definitely will suppress a significant amount of cabin noise.
And you DO know that!
How's she running?
05-10-2009, 06:57 PM
#39
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From the inside of the cabin its fairly quiet. Love this time of year though when I can put windows down and enjoy the exhaust sound. Its music to my ears
05-10-2009, 08:19 PM
#40
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I come from the cobra world, so the in cabin drone right no is NOTHING. Wait until mufflers go on, then you will hear some drone
Right now all I have is the stock system with the resonator delete. I am going 3 " from the rear axle back which is really nothing. I am just looking for a super aggressive exhaust. I retained both sets of mufflers so far as I will get the kleemans down the road and run only the secondary cats.
Right now all I have is the stock system with the resonator delete. I am going 3 " from the rear axle back which is really nothing. I am just looking for a super aggressive exhaust. I retained both sets of mufflers so far as I will get the kleemans down the road and run only the secondary cats.
05-11-2009, 01:39 AM
#41
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keep in mind that you're coming from one of the best sounding v8's ever produced...a sound that you'll never be able to duplicate with this platform.
also, dynamat is some heavy stuff so if you get carried away with it you'll be adding a noticable amount of weight.
also, dynamat is some heavy stuff so if you get carried away with it you'll be adding a noticable amount of weight.
05-11-2009, 02:01 AM
#42
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2003 cl55 (sold)
I had no rear cats and no muffler with 3" from axle back and it was just too loud and obnoxious, plus I felt like I lost quite a bit of low end. Sounded louder but felt slower. Muffler guy told me I lost about 1.5 lb back pressure per cat and about .5 lb back pressure with each muffler. Decided to change it to a 3" cat back system and I love it. Put secondary cats back in, did 3" x pipe after secondary cats (plus still have factory h pipe in front of cats) to all the rest 3" pipe to magnaflow mufflers. Sounds so much better and a hell of a lot quieter. Definitely smoother and I got back that low end and smoothness that I was missing.
Last edited by jicl55; 05-11-2009 at 02:06 AM.
05-11-2009, 02:04 AM
#43
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Its all good as long as you shed weight in other ways
but as stated just dont go too crazy with it
Last edited by Fr33kn63; 05-11-2009 at 02:07 AM.
05-11-2009, 09:18 AM
#45
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I have a 63 and and as my sig says no 2ndary cats and 3" SS pipes to 3" SS X-pipe and 3" SS piping back to stock mufflers.
IMO I gained a little HP.
This same setup on a 55 from what I have heard could loose power for them. I heard on the 55 the primary cats should be deleted and leave the 2nd cats in place, but the 3" piping and x-pipe is fine on 55's too.
05-11-2009, 11:54 AM
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How does it feel? Mine felt a lot more "sluggish" with the cat delete and no mufflers with 3" axle back ..... noticeably slower. After I put the secondary cats back in, mufflers back in, then extended the 3" section to the secondary cats (with a 3" x-pipe) the power difference/delivery is noticeably smoother and stronger. Losing those cats and mufflers were a bad idea, at least from what I can tell. Free flowing is good.... the difference in pipe from the stock 2.75" to 3" is not that huge of a jump (like from 1.5" pipe to 3" pipe), but I think we NEED some back pressure there. Like I said, the muffler guy said I lost about 1.5 lb back pressure per secondary cat delete (always have had the stock primaries on there, so that is not a variable) and about .5 lb per muffler.... that equates to a total of 4 lb of back pressure lost, plus whatever the 3" piping does to decrease back pressure as well. All I can vouch for is how it feels for me, and it feels 100% improved. Then again, everyone's car is different with different setups, so who knows, but this has been my experience.
...what were the rwhp #'s?
05-11-2009, 11:13 PM
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Fr33kn63: I have a 55. Hmm, if I deleted prims instead of second I would get a CEL though, right?
jicl55: I'm not sure if its "sluggish" like it feels fast but I don't really know how to judge cause I forgot how it felt before. When I gut the mufflers, though, that's not the same as just running straight pipes right? Because I still have the baffles and everything so my backpressure should be fine?
However, according to you, I lost ~3lbs of backpressure because I took out my 2 secondary cats?
jicl55: I'm not sure if its "sluggish" like it feels fast but I don't really know how to judge cause I forgot how it felt before. When I gut the mufflers, though, that's not the same as just running straight pipes right? Because I still have the baffles and everything so my backpressure should be fine?
However, according to you, I lost ~3lbs of backpressure because I took out my 2 secondary cats?
05-11-2009, 11:36 PM
#50
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