reducing drone

Zsteve · 11-27-2009, 09:05 PM

Quote:

Originally Posted by Matt

Does the Ark exhaust have the pipes you are talking about?

Yep looks like they do but also looks like it went into a deadend resonator too. That might be to reduce the length of the piping. I think the side pipe has to be the correct lambda length (which I guess is the length it takes a freq to travel) to achieve that 180 degree out of phase and maybe that wider pipe helped trick it to that. Im telling you this has me really curious now.

Actually the Ark and FI are very similar, Ark just has the side pipes.

Modshack · 11-27-2009, 09:21 PM

Quote:

Originally Posted by Zsteve

So if add a side pipe would reduce drone even 50% what size diameter and length would be required? Looking for all the math/science guys on this one.

I think it's a litte more complex than that... Typically those chambers are called Helmholtz resonators. They are used to dampen resonances
but usually used in intakes. There is one on the Z in the drivers side intake accordion. You'll see them on many cars in various shapes, tuned to cancel out natural frequencies. I think it would take some smart acoustical engineer to come up with something for the exhaust that would work on your system..

Zsteve · 11-27-2009, 09:38 PM

I was researching some more and saw this with one of my googles:

I’m a car-audio installer. An instructor at a training conference told me that clitoral resonance is 33 hertz, give or take, depending on the woman’s weight. This means that anything vibrating 33 times per second will cause the clitoris to resonate. Howard Stern made an example of this in Private Parts when he got a woman off by having her sit on a speaker, and just about any woman will respond to a bass note at that frequency if your subwoofer can play that low. Is there any truth to this? – J.B., Yuma Arizona

At 2K rpms 33 hertz is the drone freq:

So our girls should be jumping with pleasure when riding in our cars. Gonna have to get the wife to give it a try, maybe she will like the exhaust more then.

spearfish25 · 11-27-2009, 09:55 PM

Quote:

Originally Posted by m4a1mustang

I think the Stillen CBE alone sounds good, but if you throw HFCs on it really sounds like crap. Some CBEs get very raspy when you add HFCs and the Stillen is one of those.

Hmmm, interesting. Did you have the Stillen with HFCs or just heard someone else's? Video or in person?

Most Stillen CBE owners on here have the HFCs as well. They seem to really like it, but again this could be owner-bias.

When I put the Stillen CBE on my car (No HFCs), the sound was noticeably louder and really a nice improvement. Having had it on the car for about 2-3 months now, I think I can go for another step up in loudness. There is ZERO drone with the Stillen CBE alone. I was going to add HFCs sometime in the next few months. However, I'm curious about this comment from M4A1. His review of the FI exhaust was an important part of my decision to go with the Stillen exhaust (and so far so good...I'm happy).

As for people giving M4A1 a hard time for saying the FI has some 2k drone...more and more people are admitting the same finding. Also, come on guys, we're above ragging on someone for sharing their opinion. Don't hate the player, hate the drone.

m4a1mustang · 11-27-2009, 10:37 PM

Quote:

Originally Posted by spearfish25

Hmmm, interesting. Did you have the Stillen with HFCs or just heard someone else's? Video or in person?

Most Stillen CBE owners on here have the HFCs as well. They seem to really like it, but again this could be owner-bias.

When I put the Stillen CBE on my car (No HFCs), the sound was noticeably louder and really a nice improvement. Having had it on the car for about 2-3 months now, I think I can go for another step up in loudness. There is ZERO drone with the Stillen CBE alone. I was going to add HFCs sometime in the next few months. However, I'm curious about this comment from M4A1. His review of the FI exhaust was an important part of my decision to go with the Stillen exhaust (and so far so good...I'm happy).

As for people giving M4A1 a hard time for saying the FI has some 2k drone...more and more people are admitting the same finding. Also, come on guys, we're above ragging on someone for sharing their opinion. Don't hate the player, hate the drone.

Video and in person.

But yeah... I have gotten a bad rap for that, even though I have expressly stated many times it's not that bad and I don't regret my choice one bit. Pisses me off! I just share my experience to the best of my ability and hope that it helps people make an informed decision.

F.I. Inc. · 11-27-2009, 11:20 PM

Ok I would like to chime in on this. I have read through every reply here and would like to offer my input.

There are many factors to take in to account when designing a system.

-Sound
-Weight
-PERFORMANCE
-Aesthetics

Now me personally I do not feel that the drone at 2000-2400 RPM's is obtrusive. Again, this is me and sound is subjective. We are not in the business of putting a system out there just to put it out there, like some of our competitors who I will not name. If I felt the drone was overwhelming I would of made changes to compensate. I hear some comment on other systems and say they have no drone. Well, look at the design, some have suitcase mufflers which are horrible for performance and weigh a ton. Who wants to put an aftermarket system on their car that weighs 10-20 pounds over stock. Others have to compensate with giant silencers which divert the exhaust flow and again, affect performance and look like scuba tanks hanging off of your car.
To date we have sold 60 cat back exhaust systems and over 50 of them are installed. I can count on less than one hand how many people are either bothered or somewhat bothered by the drone. I have spoke to some of them on my own and they tell me that they would do it all over again knowing what they know now. I hear the same thing, there is some drone at 2000-2400ish but the sound is incredible.

"Is is so deep and smooth under acceleration and I just love it Tony".

-We are a minimum of 10 pounds lighter than stock.
-We picked up and average of over 20 RWH over stock.
-The exhaust looks aggressive yet classy.
-You will not find better customer service and I will stand behind that and my business until the end!!!
-To date: naturally aspirated we have higher gains over stock than any other 2.5" system on the market. And like I always say, put this system in a force inducted application, we will decimate any other 2.5" system in sound and performance.

The bottom line is, overall we feel that we have designed a system that brings the best qualities out of this wonderful car. In the end if the only major complaint is the drone that some feel they get, I will take it any day of the week.

If anyone has any questions, please do not hesitate to ask. I always have an open door policy...

Thank you, Tony

m4a1mustang · 11-27-2009, 11:29 PM

And that is the truth.

I know some people are very selective readers when they go through my posts regarding the FI exhaust, but I can't tell you how many times I have compared the sound to a Mustang Cobra mixed with a Ferrari F355. I absolutely rave about the sound. But I guess since I'm not afraid to talk about the drone that I experience some people jump on that and only that... but if they really read everything I have to say I always disclaim that 1) it's subjective, 2) it isn't that much of a bother for me..., and 3) it sounds f'in amazing.

For probably the 100th time... I don't regret buying the system one bit. This is without a doubt the best sound for this car... when all others fail to produce the low-mid range beefy sound and spit out a lot of rasp up top, Tony has come up with something that is deep and powerful down low and screams like a refined exotic up top. ABSOLUTELY ZERO RASP.

Nikon FM · 11-27-2009, 11:50 PM

Quote:

Originally Posted by Modshack

I think it's a litte more complex than that... Typically those chambers are called Helmholtz resonators. They are used to dampen resonances
but usually used in intakes. There is one on the Z in the drivers side intake accordion. You'll see them on many cars in various shapes, tuned to cancel out natural frequencies. I think it would take some smart acoustical engineer to come up with something for the exhaust that would work on your system..

Ark Performance - Type 2 Stainless Steel True-Dual Exhaust

"Here's my 2 cents:

Essentially the second set of pipes are Helmholtz resonators, this is purely acoustic in nature and not necessarily performance related. The performance related aspects of this system can be attributed to the less restrictive flow path compared to the OEM system (including the x-pipe). The design "engineers" need to speak up to a level of explanation that does not give away their tricks.

I like this system, I think I'll purchase it but will not move until we see comparative dynos."

The side branches most likely are targeting a limited RPM range where flow conditions set up the "drone". The ~2k rpm condition (where drone occurs) is probably the targeted design point for the resonators. Higher RPMs mean a different flow so this becomes an off condition for the resonator design and the side pipes are there for looks.....but I kind of like them anyway

Done with the book...

TeamARK · 11-28-2009, 03:17 AM

Quote:

Originally Posted by Nikon FM

Ark Performance - Type 2 Stainless Steel True-Dual Exhaust

"Here's my 2 cents:

Essentially the second set of pipes are Helmholtz resonators, this is purely acoustic in nature and not necessarily performance related. The performance related aspects of this system can be attributed to the less restrictive flow path compared to the OEM system (including the x-pipe). The design "engineers" need to speak up to a level of explanation that does not give away their tricks.

I like this system, I think I'll purchase it but will not move until we see comparative dynos."

The side branches most likely are targeting a limited RPM range where flow conditions set up the "drone". The ~2k rpm condition (where drone occurs) is probably the targeted design point for the resonators. Higher RPMs mean a different flow so this becomes an off condition for the resonator design and the side pipes are there for looks.....but I kind of like them anyway

Done with the book...

I would want the customers to have it any other way. Our final production comes in Dec 15th. We have already set aside a day to bring detailed results with videos. Until then, if you have any questions regarding our systems please do not hesitate to ask.

Alex

Zsteve · 11-28-2009, 09:54 AM

Some interesting stuff here. For those still pondering which exhaust, let me say this, FIs exhaust IMO sounds the best overall and I love it 90% of the time. The 10% I dont like is the 2K drone and it may be worse for me due to being an AT, even Tony says its worse on an AT. Looks is a 10/10, love the look, better than any other so far. Performance is there, I usedmy Gtech prior to the exhaust and did a 0 60 in 5.1 secs. That took me about 6-8 tries to get that. Went out the other day and the roads were still damp and had debre on them from days of rain and in the 2 tries I did I got a 5.2 secs in "D" mode, which before I was getting 5.4 secs. And a 5.1 in paddle mode but I couldnt get a good grip due to road conditions. Even before in paddle mode I was getting 5.2s and even a 5.3, now I easlily got the 5.1. When the temp is around 70 degrees I will go back out and hope the road debre isnt as bad either and do a bunch of runs. I think I shaved .2 secs of my 0 60 time with this exhaust.

Now as an older guy who travels to my daugthers college alot to visit and the wife is with me, and having an AT that loves to put the rpms at 2K I would love to find a reasonable fix to this just for those times. I wouldnt mind an extra 2-4 pounds on the exhaust for some side resonators to help this.

Tony I still think you have a super product and I would still get it over the others again but maybe an option of side resonators for those that might want would be a nice touch.

Just my 2 cents.

11-27-2009, 09:38 PM	#33 (permalink)
Zsteve A True Z Fanatic Join Date: Sep 2009 Location: TX Posts: 3,298 Drives: the 2 balled club Rep Power: 22	I was researching some more and saw this with one of my googles: I’m a car-audio installer. An instructor at a training conference told me that clitoral resonance is 33 hertz, give or take, depending on the woman’s weight. This means that anything vibrating 33 times per second will cause the clitoris to resonate. Howard Stern made an example of this in Private Parts when he got a woman off by having her sit on a speaker, and just about any woman will respond to a bass note at that frequency if your subwoofer can play that low. Is there any truth to this? – J.B., Yuma Arizona At 2K rpms 33 hertz is the drone freq: So our girls should be jumping with pleasure when riding in our cars. Gonna have to get the wife to give it a try, maybe she will like the exhaust more then. __________________ 2010 LS3 C6 Silver coupe corvette

11-27-2009, 11:20 PM	#36 (permalink)
F.I. Inc. The370Z.com Sponsor Join Date: Feb 2009 Location: Simi Valley, CA Posts: 2,989 Drives: 2010 GT-R/2007 F-250 Rep Power: 685	Ok I would like to chime in on this. I have read through every reply here and would like to offer my input. There are many factors to take in to account when designing a system. -Sound -Weight -PERFORMANCE -Aesthetics Now me personally I do not feel that the drone at 2000-2400 RPM's is obtrusive. Again, this is me and sound is subjective. We are not in the business of putting a system out there just to put it out there, like some of our competitors who I will not name. If I felt the drone was overwhelming I would of made changes to compensate. I hear some comment on other systems and say they have no drone. Well, look at the design, some have suitcase mufflers which are horrible for performance and weigh a ton. Who wants to put an aftermarket system on their car that weighs 10-20 pounds over stock. Others have to compensate with giant silencers which divert the exhaust flow and again, affect performance and look like scuba tanks hanging off of your car. To date we have sold 60 cat back exhaust systems and over 50 of them are installed. I can count on less than one hand how many people are either bothered or somewhat bothered by the drone. I have spoke to some of them on my own and they tell me that they would do it all over again knowing what they know now. I hear the same thing, there is some drone at 2000-2400ish but the sound is incredible. "Is is so deep and smooth under acceleration and I just love it Tony". -We are a minimum of 10 pounds lighter than stock. -We picked up and average of over 20 RWH over stock. -The exhaust looks aggressive yet classy. -You will not find better customer service and I will stand behind that and my business until the end!!! -To date: naturally aspirated we have higher gains over stock than any other 2.5" system on the market. And like I always say, put this system in a force inducted application, we will decimate any other 2.5" system in sound and performance. The bottom line is, overall we feel that we have designed a system that brings the best qualities out of this wonderful car. In the end if the only major complaint is the drone that some feel they get, I will take it any day of the week. If anyone has any questions, please do not hesitate to ask. I always have an open door policy... Thank you, Tony __________________ *Follow us on Facebook: Fast Intentions Inc.* Phone: (805) 522-FAST (3278) Email: tony@fastintentions.com www.fastintentions.com "FUELED BY PASSION"

11-27-2009, 11:29 PM	#37 (permalink)
m4a1mustang A True Z Fanatic Join Date: Feb 2009 Location: Northern VA Posts: 55,385 Drives: on two wheels Rep Power: 6962	And that is the truth. I know some people are very selective readers when they go through my posts regarding the FI exhaust, but I can't tell you how many times I have compared the sound to a Mustang Cobra mixed with a Ferrari F355. I absolutely rave about the sound. But I guess since I'm not afraid to talk about the drone that I experience some people jump on that and only that... but if they really read everything I have to say I always disclaim that 1) it's subjective, 2) it isn't that much of a bother for me..., and 3) it sounds f'in amazing. For probably the 100th time... I don't regret buying the system one bit. This is without a doubt the best sound for this car... when all others fail to produce the low-mid range beefy sound and spit out a lot of rasp up top, Tony has come up with something that is deep and powerful down low and screams like a refined exotic up top. ABSOLUTELY ZERO RASP. __________________ - Steve Zs & Coffee - Saturdays at 10AM in Fairfax, VA and Columbia, MD (Click the banner!) LIKE us on Facebook!

11-28-2009, 09:54 AM	#40 (permalink)
Zsteve A True Z Fanatic Join Date: Sep 2009 Location: TX Posts: 3,298 Drives: the 2 balled club Rep Power: 22	Some interesting stuff here. For those still pondering which exhaust, let me say this, FIs exhaust IMO sounds the best overall and I love it 90% of the time. The 10% I dont like is the 2K drone and it may be worse for me due to being an AT, even Tony says its worse on an AT. Looks is a 10/10, love the look, better than any other so far. Performance is there, I usedmy Gtech prior to the exhaust and did a 0 60 in 5.1 secs. That took me about 6-8 tries to get that. Went out the other day and the roads were still damp and had debre on them from days of rain and in the 2 tries I did I got a 5.2 secs in "D" mode, which before I was getting 5.4 secs. And a 5.1 in paddle mode but I couldnt get a good grip due to road conditions. Even before in paddle mode I was getting 5.2s and even a 5.3, now I easlily got the 5.1. When the temp is around 70 degrees I will go back out and hope the road debre isnt as bad either and do a bunch of runs. I think I shaved .2 secs of my 0 60 time with this exhaust. Now as an older guy who travels to my daugthers college alot to visit and the wife is with me, and having an AT that loves to put the rpms at 2K I would love to find a reasonable fix to this just for those times. I wouldnt mind an extra 2-4 pounds on the exhaust for some side resonators to help this. Tony I still think you have a super product and I would still get it over the others again but maybe an option of side resonators for those that might want would be a nice touch. Just my 2 cents. __________________ 2010 LS3 C6 Silver coupe corvette