Let's talk about drone and custom exhausts

[allmotor_2000]

Originally Posted by epiphanyray

So two 32.8 inch long, sealed on both ends, hollow pipes. I make a hole in the main pipe (bank 1 and 2), and weld this on there at a 90 degree angle? like this (view crappy drawing) and image.

what diameter should these pipes be? 3? 4 inches?

Exhaust is 3" so 2" is fine for the resonators...

[allmotor_2000]

Originally Posted by apexlocator

Those look like helmholtz resonators employed by some aftermarket exhaust systems. I see them mostly in the JDM market...

These arnt helmholtz although they do the same thing via different acoustic principles...

[ur20v]

Ha, the old muffler delete/turner exhaust drone problem, been there done that and my wife refused to go i the car as well lol. Went to properly designed Ti system and have zero drone now.

[2016-M5]

Ive just got used to the drone now, i have no cats, resonators, or mufflers left and a hand made extended X pipe, and it sounds incredible. I installed heavy duty Dynomat in the trunk which helped a lot

[TheHouseWon]

Yes, Helmholtz have been around for a while and do work. That is certainly a good option if you like the sound of your current set up. You can also replace stock front resonators with thicker ones for the drone but they will reduce the volume and change the tone.

I would recommend Eisenmann Sport + Catless. I can't get enough of that exhaust note! I take the long way home every chance I get and find tunnels to go through for a quick 4k rpm pull. Best part: NO DRONE even with the valves open.

E-sport will cost more than the custom jobs, but they make up for it in fit, finish, sound, and quality. Since you've already got the tips and muffler set up, Eisenmann may no longer be an option unless you can sell your set up. Either way, you have to get rid of the drone...I had muffler deletes and the drone got to me. With my current set up, I am 100% happy with my decision, it is a beautiful sound

evilb can attest to the quality of eisenmann!

[evilb]

Originally Posted by TheHouseWon

Yes, Helmholtz have been around for a while and do work. That is certainly a good option if you like the sound of your current set up. You can also replace stock front resonators with thicker ones for the drone but they will reduce the volume and change the tone.

I would recommend Eisenmann Sport + Catless. I can't get enough of that exhaust note! I take the long way home every chance I get and find tunnels to go through for a quick 4k rpm pull. Best part: NO DRONE even with the valves open.

E-sport will cost more than the custom jobs, but they make up for it in fit, finish, sound, and quality. Since you've already got the tips and muffler set up, Eisenmann may no longer be an option unless you can sell your set up. Either way, you have to get rid of the drone...I had muffler deletes and the drone got to me. With my current set up, I am 100% happy with my decision, it is a beautiful sound

evilb can attest to the quality of eisenmann!

Yeah, it's high quality. I also have catless but with the E-Race, and if there's drone, I don't notice it at all. It sounds fantastic.

[m5james]

Originally Posted by allmotor_2000

Yes - you have to cancel out the drone frequencies by installing a capped tube (per bank). The length of the tube depends on the frequency (based on RPM) of the drone. The tube needs to come off the main exhaust path at 90-degrees. Lower the drone RPM, longer the tube...

They are just capped tubes... so you don't buy them. Need a fabricator to make them.

I had calculated this for various RPM's and the resulting tube length.

http://www.xbimmers.com/forums/showp...0&postcount=22

[steeve13m]

I have drone from 1100RPM to 2000RPM.....what length Helmholtz pipe have you all used and how are the results?

[steeve13m]

Originally Posted by allmotor_2000

if you want to eliminate the drone, you need 1/4-wave resonators. I designed this on my previous car... full straight-thru system

What length did you use? I have drone from 1100 to 2000rpm what length you recommend?

http://synapseengineering.com/products/nodrone.html

[allmotor_2000]

Originally Posted by steeve13m

What length did you use? I have drone from 1100 to 2000rpm what length you recommend?

http://synapseengineering.com/products/nodrone.html

Research....

http://f10.m5post.com/forums/showpos...3&postcount=15

[steeve13m]

Originally Posted by allmotor_2000

Research....

http://f10.m5post.com/forums/showpos...3&postcount=15

yes I had seen that I was wondering what length did you use in your application specifically?

[allmotor_2000]

Doesn’t matter if the drone RPM was different!

[TheHouseWon]

Safe to say 30 inches would suffice

[steeve13m]

anyone try these?

http://synapseengineering.com/products/nodrone.html

[Morteng70]

Originally Posted by TheHouseWon

Yes, Helmholtz have been around for a while and do work. That is certainly a good option if you like the sound of your current set up. You can also replace stock front resonators with thicker ones for the drone but they will reduce the volume and change the tone.

I would recommend Eisenmann Sport + Catless. I can't get enough of that exhaust note! I take the long way home every chance I get and find tunnels to go through for a quick 4k rpm pull. Best part: NO DRONE even with the valves open.

E-sport will cost more than the custom jobs, but they make up for it in fit, finish, sound, and quality. Since you've already got the tips and muffler set up, Eisenmann may no longer be an option unless you can sell your set up. Either way, you have to get rid of the drone...I had muffler deletes and the drone got to me. With my current set up, I am 100% happy with my decision, it is a beautiful sound

evilb can attest to the quality of eisenmann!

Hi, sorry for entering so late in the thread.......I am looking at the same set up, just ordered the E-Sport two days ago and really want to go catless but I have heard so much about that smell.....how bad is it?...I am considering the Supersprint DP`s......if the smell is to bad, would like 300 cell high flow sport cats take that away? And where would you mount them on the OEM exhaust...?

Morten

[Craze]

Can anyone confirm these eliminate drone on the m5 if straight piped???

Ive booked to get some made but would like some feedback before i spend the money

Also the capped length tube calculation does that include the bend also??? Or just the straight section

[F10CPROG]

Just a quick suggestion, would an uprated x section help with cancelling out the drone.
The Porsche flat 6 drone is usually caused by the 2 banks of the engine having entirely seperate exhausts, joining them with an X peice cancels the drone.

[Craze]

Mine has an x and drones

[Craze]

Well doesnt seem like anyone has talked about this j pipe and eliminating the drone

Im getting a shop next week to make a 2inch stainless j pipe and we will trial different lengths
Only drones at 1500-2000rpm as its full rpi gtm straight pipe and catless
That little bit of drone really spoils when driving around town

[Dwaynos]

Originally Posted by Craze

Well doesnt seem like anyone has talked about this j pipe and eliminating the drone

Im getting a shop next week to make a 2inch stainless j pipe and we will trial different lengths
Only drones at 1500-2000rpm as its full rpi gtm straight pipe and catless
That little bit of drone really spoils when driving around town

I've seen people installing things like the Magnaflow 12469. Its a pretty much a baffled x pipe, I've seen them installed where the factory m5 resonators are located. Someone on the forum did it bit I can't remember who, got great results.

[Craze]

Ive had a set made and fitted as per previous pics

Drone is now basically gone

However exhaust sounds a little quieter inside the car
It may be in fact still as loud outside im not sure
Fabricator hates me! He did beautiful work

So now im catless with rpi gtm full straight pipe exhaust and also drone free hahaha

The length of j pipe is 32 inches
I wanted 35 but he said we ran outta room

[Craze]

Also re aligned a tip and made them stick out less
Looks much better