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i thought the H valve opens when the engine is under load but didnt think it made it quieter when open.
i guess you came to that conclusion because with the valve open youve lost the throaty tone?
have you thought of doing a muffler delete? Kinda like the AWE Track.
If it is true that the exhaust guys have kept the valve permanently open then it has definitely lost a lot of great sound, it is very noticeable.
Makes sense if you think about it. The H pipe is going to let the sound waves interfere as they come down from each side and cancel some out. With the valve closed this does not occur and hence more exhaust volume and separation. Therefore, contrary to what many have thought, the valve closes to increase some of the sounds and opens to cancel some of the noise out.
I really liked the sound with the cat delete when the valve was working. With it constantly open it is too quiet for me.
Last edited by Hyperion728; 10-12-2019 at 01:36 AM.
If it is true that the exhaust guys have kept the valve permanently open then it has definitely lost a lot of great sound, it is very noticeable.
Makes sense if you think about it. The H pipe is going to let the sound waves interfere as they come down from each side and cancel some out. With the valve closed this does not occur. Therefore, contrary to what many have thought, the valve closes to increase some of the sounds and opens to cancel some of the noise out.
I really liked the sound with the cat delete when the valve was working. With it constantly open it is too quiet for me.
In that case I wonder if when the valve is closed, is it completely closed or only partially because if it completely closes then wouldnt that defeat the purpose of a crossover such as a H or X pipe?
I think this is what they are doing: they use an H pipe (like a lot of other manufacturers) to reduce sound volume and/or tune the sound of the exhaust throughout the rev range with the valve in various positions in combination with the muffler valves.
Remember that for turbocharged applications the scavenging effect of an X merge or H pipe isn’t going to be important for the efficiency of the exhaust, totally different story for a naturally aspirated V configuration engine, where it may be very important for performance (and also sound control) as the gases arrive in a much more pulsatile manner from the exhaust ports vs how the gases come off the backside of a turbine.
Most cars that have an H pipe don’t have a valved one but since the sound quality is so important to AMG and their customers they have placed it there to have more options than simply have it fixed. The thing that I think many have not appreciated is that the H pipe valve OPEN is actually to decrease and smoothen sound volume rather than increase it. When it is closed you have two separate exhaust paths with less sound wave interference and it will sound completely different as I have found with the valve permanently open. I’ll let you guys know what it is like with it permanently closed. The car sounds much more ‘dirty’, nasty and meaty when the valve is CLOSED vs OPEN. Open is to quieten the thing down and possibly reduce drone. Will let you know asap the outcome of my experiment.
Last edited by Hyperion728; 10-12-2019 at 01:48 AM.
2019 owner checking in. Had a loud rattle in the H-pipe area on cold starts (but no sound while driving, at least from the inside). Took it to the dealer and they are swapping the entire exhaust under warranty. The tech said he heard a rattle from the rear as well. Kind of disappointing with only 6K miles on the clock but whatever.
Side note, they put me in the new GLE350 loaner and I am smitten. MBUX is on another level.
Reporting back.
H pipe now permanently closed and the car sounds fantastic again.
The rumble is back and more volume, especially on trailing throttle from higher rpm. Mid-range sound mint! Love it.
Without a doubt, if you are chasing volume and the deep, rich exhaust note you want the H pipe valve CLOSED not OPEN. H pipes reduce volume and exhaust sound separation. It is not subtle, very noticeable.
Last edited by Hyperion728; 10-14-2019 at 07:36 PM.
Reporting back.
H pipe now permanently closed and the car sounds fantastic again.
The rumble is back and more volume.
Without a doubt, if you are chasing volume and the deep, rich exhaust note you want the H pipe valve CLOSED not OPEN. H pipes reduce volume and exhaust sound separation. It is not subtle, very noticeable.
very nice. Now i have to figure out to how to do this because i already cut the valve off and replaced that H section with a straight pipe
very nice. Now i have to figure out to how to do this because i already cut the valve off and replaced that H section with a straight pipe
Easiest way is to got them to cut the H pipe and slip in a small disk of metal and weld that in. That is basically what they did for me, the valve is all still there etc so looks stock.
Easiest way is to got them to cut the H pipe and slip in a small disk of metal and weld that in. That is basically what they did for me, the valve is all still there etc so looks stock.
was the disc welded in right in the middle of that H section? And does it completely block it or are there gaps in the corner still?
The problem is weak tension in the on the three exhaust flaps L, R & Center. Request that your dealership open a PTSS Case with MBUSA Engineering and they'll get to the solution much faster - the tension needs to be increased on all three flaps. My car had 3 exhaust systems replacements and the rattling always came back - it took my dealer 8 weeks to identify the issues and 2 days to fix it once opening the PTSS case with Engineering.
The problem is weak tension in the on the three exhaust flaps L, R & Center. Request that your dealership open a PTSS Case with MBUSA Engineering and they'll get to the solution much faster - the tension needs to be increased on all three flaps. My car had 3 exhaust systems replacements and the rattling always came back - it took my dealer 8 weeks to identify the issues and 2 days to fix it once opening the PTSS case with Engineering.
Thanks, I am now experiencing rattling from the muffler flaps also!
I will refer to your post. Any idea how they increase the tension? Different flap spring?
Regards
Easiest way is to got them to cut the H pipe and slip in a small disk of metal and weld that in. That is basically what they did for me, the valve is all still there etc so looks stock.
Are you not essentially just straight piping them at that point? Might as well cut the H out and have two new pieces cleanly welded in. I assume that would sound the same as having the flap always closed?
I didn't realize the awe sims worked on the valved h, I already have my mufflers straight piped with the sims and have secondary cat delete. I might straight pipe my H now too. With by current setup the car is pretty loud idling and low rpm but I'd like more volume when getting on it. It seems a bit tame to me mid rpm and higher. I just assumed the turbos muffled the volume when pushing the car. SO knowing the car is quieter with h open and louder with it closed, what position is the H in when idling or low rpm? Im just trying to judge what changes in sound ill have to my car if I add a straight piped H section to my already straight piped mufflers and 2nd cats. It sounds like what you're saying is the H valve, when operating, actually opens at higher rpm (quieting it down the car).
Edit: also now that I think of it, I'm surprised that made a difference for Hyperion since there is a second H pipe down stream with no flap. So theres an H always open anyways.
Are you not essentially just straight piping them at that point? Might as well cut the H out and have two new pieces cleanly welded in. I assume that would sound the same as having the flap always closed?
I didn't realize the awe sims worked on the valved h, I already have my mufflers straight piped with the sims and have secondary cat delete. I might straight pipe my H now too. With by current setup the car is pretty loud idling and low rpm but I'd like more volume when getting on it. It seems a bit tame to me mid rpm and higher. I just assumed the turbos muffled the volume when pushing the car. SO knowing the car is quieter with h open and louder with it closed, what position is the H in when idling or low rpm? Im just trying to judge what changes in sound ill have to my car if I add a straight piped H section to my already straight piped mufflers and 2nd cats. It sounds like what you're saying is the H valve, when operating, actually opens at higher rpm (quieting it down the car).
Edit: also now that I think of it, I'm surprised that made a difference for Hyperion since there is a second H pipe down stream with no flap. So theres an H always open anyways.
i think thats a solution only for when you start hearing rattling sounds from the valve. If the valve is functioning properly then the car does a good job at managing sound and doesnt get quiet.
AWE doesnt sell individual components but the i think a good setup wouldve been their H pipe followed by a custom 3” straight pipe to the exhaust tips.
i think thats a solution only for when you start hearing rattling sounds from the valve. If the valve is functioning properly then the car does a good job at managing sound and doesnt get quiet.
AWE doesnt sell individual components but the i think a good setup wouldve been their H pipe followed by a custom 3” straight pipe to the exhaust tips.
He said when he did the sim it kept the valved H open all the time making it quieter. That makes me think straight piping that portion would make the car louder above 2k (or whatever rpm the flap opens up the H). He's essentially straight piping the H by welding a piece in the middle to block it off permanently.
You straight piped the valved H, right? If you did it on a separate occasion to when you did your secondary cat delete, how did it change the sound?
He said when he did the sim it kept the valved H open all the time making it quieter. That makes me think straight piping that portion would make the car louder above 2k (or whatever rpm the flap opens up the H). He's essentially straight piping the H by welding a piece in the middle to block it off permanently.
You straight piped the valved H, right? If you did it on a separate occasion to when you did your secondary cat delete, how did it change the sound?
Originally Posted by Hyperion728
Thanks, I am now experiencing rattling from the muffler flaps also!
I will refer to your post. Any idea how they increase the tension? Different flap spring?
Regards
Shane - Straight piped just the valved section so essentially i still have the H with no valve and that is what Hyperion was referring too that the car lost a bit of the throaty sound. Also my exhaust guy said if i take out the crossover H section and just do straight pipe then it would sound more raspy
Hyperion - With the valve now welded closed, would you say the car sounds better than it did with a functioning H valve or does it now sound the same?
Are you not essentially just straight piping them at that point? Might as well cut the H out and have two new pieces cleanly welded in. I assume that would sound the same as having the flap always closed?
I didn't realize the awe sims worked on the valved h, I already have my mufflers straight piped with the sims and have secondary cat delete. I might straight pipe my H now too. With by current setup the car is pretty loud idling and low rpm but I'd like more volume when getting on it. It seems a bit tame to me mid rpm and higher. I just assumed the turbos muffled the volume when pushing the car. SO knowing the car is quieter with h open and louder with it closed, what position is the H in when idling or low rpm? Im just trying to judge what changes in sound ill have to my car if I add a straight piped H section to my already straight piped mufflers and 2nd cats. It sounds like what you're saying is the H valve, when operating, actually opens at higher rpm (quieting it down the car).
Edit: also now that I think of it, I'm surprised that made a difference for Hyperion since there is a second H pipe down stream with no flap. So theres an H always open anyways.
Originally Posted by untamedd
Shane - Straight piped just the valved section so essentially i still have the H with no valve and that is what Hyperion was referring too that the car lost a bit of the throaty sound. Also my exhaust guy said if i take out the crossover H section and just do straight pipe then it would sound more raspy
Hyperion - With the valve now welded closed, would you say the car sounds better than it did with a functioning H valve or does it now sound the same?
There is only one H pipe on the exhaust, the second part that looks like an H pipe is just a brace.
You could cut the H pipe out all together but my exhaust shop didn’t as it was a lot easier to do it the way they have, plus I suppose you keep the strength of the whole system at that point too.
The car sounds much more deep and nasty with the H pipe closed. It sounds a bit better to me than with a functioning H pipe valve but I don’t think it is a huge difference. The biggest difference was when it was always open, too quiet and not throaty anymore.
What AMG are doing with the flap would depend what mode you were in. Ie in Sport+ or Race I think it is probably closed most of the time but in other modes it is open or partially open depending on RPM and load etc. In comfort it is probably open all the time. If you have straight pipes on the mufflers it is going to get very loud I would think. I was perfectly happy with the sound of it with the secondary cat delete and a functioning H pipe but was not happy with an H pipe always open.
The real H pipe Brace
Last edited by Hyperion728; 10-19-2019 at 03:26 AM.
There is only one H pipe on the exhaust, the second part that looks like an H pipe is just a brace.
You could cut the H pipe out all together but my exhaust shop didn’t as it was a lot easier to do it the way they have, plus I suppose you keep the strength of the whole system at that point too.
The car sounds much more deep and nasty with the H pipe closed. It sounds a bit better to me than with a functioning H pipe valve but I don’t think it is a huge difference. The biggest difference was when it was always open, too quiet and not throaty anymore.
What AMG are doing with the flap would depend what mode you were in. Ie in Sport+ or Race I think it is probably closed most of the time but in other modes it is open or partially open depending on RPM and load etc. In comfort it is probably open all the time. If you have straight pipes on the mufflers it is going to get very loud I would think. I was perfectly happy with the sound of it with the secondary cat delete and a functioning H pipe but was not happy with an H pipe always open.
The real H pipe Brace
I used to think the same about not having mufflers but everyone Ive spoken to with an AWE Track Exhaust, they all love it. So its something id like to try out but need to get my hands on a good H pipe first.
The problem is weak tension in the on the three exhaust flaps L, R & Center. Request that your dealership open a PTSS Case with MBUSA Engineering and they'll get to the solution much faster - the tension needs to be increased on all three flaps. My car had 3 exhaust systems replacements and the rattling always came back - it took my dealer 8 weeks to identify the issues and 2 days to fix it once opening the PTSS case with Engineering.
Reporting back.
H pipe now permanently closed and the car sounds fantastic again.
The rumble is back and more volume, especially on trailing throttle from higher rpm. Mid-range sound mint! Love it.
Without a doubt, if you are chasing volume and the deep, rich exhaust note you want the H pipe valve CLOSED not OPEN. H pipes reduce volume and exhaust sound separation. It is not subtle, very noticeable.
i got this done today and it def made a big difference. I had forgotten how much more aggressive the car sounded when with a functioning H valve and now I can experience that again!
2019 Audi SQ5, 2011 Toyota Tacoma TRD 4wd, 2016 Ford Focus se Hatchback
Originally Posted by untamedd
i got this done today and it def made a big difference. I had forgotten how much more aggressive the car sounded when with a functioning H valve and now I can experience that again!
Where is this welded shut? Also, do you keep the simulator on this valve? Thanks.
i got this done today and it def made a big difference. I had forgotten how much more aggressive the car sounded when with a functioning H valve and now I can experience that again!
Fantastic! Totally agree, it’s not subtle.
For more volume and a deep rich sound, the H pipe valve is shut NOT open.
For more volume and a deep rich sound, the H pipe valve is shut NOT open.
How long did you drive for with an always open H valve?
I probably drove for a good 6 months and this honestly feels like I got a new exhaust. I really did forget how scary this car can sound with that open H valve. Im sure a lot of people will benefit from your experiment.
I ordered a mid section and was going to go custom 3” straight pipe muffler delete like the Track exhaust. Excited to hear that!
10-11-2019, 08:55 PM
