Akrapovic E92 M3 Exhaust Owner's Thread

[MrHarris]

Honestly drone isn't that annoying unless it's right around 2900-3300rpm (6MT) because then you always hear that "BAHHHH" sound going from point A to point B which sucks.

[mixja]

Originally Posted by sard

OK I found a good reference on this website.

http://www.corsaperf.com/CorsaWhatIsDrone.aspx

That sound is pretty fucking annoying lol. I don't think it really drones, at least to that extent. At the lower rpms when you give it gas, I think it makes a nice note inside the cabin which might be drone, but I don't think it's that annoying humming resonating cabin noise type. Like I said earlier, at highway speed cruising speeds, I dont' hear anything really.

You can check out my videos I made after I installed the exhaust by clicking the link below. There are several in cabin examples. Just scroll to the bottom of the pictures to reach the videos.

http://www.m3post.com/forums/showthr...ight=akrapovic

Thanks for the feedback, yeah resonance is the better term, it's like the sound you get when blowing across the top of a bottle.

I can hear it in your video with the windows rolled up, at the beginning of the video with one of the downshifts and then slightly as you accelerate away from the first corner in the video. But it doesn't sound like it's too bad.

The easiest way to test for it is to drive along in 6th or 7th gear at 2000RPM and go WOT. You will definitely hear if there are is any resonance. When I had AA HFC down pipes with factory exhaust, it was quite bad at several RPM points (2000, 2500, 4000).

[J08M3]

Just because you hear your exhaust doesn't mean there is drone. Drone is a very annoying resonance that creates this almost ringing sound inside your head. I've had it with quieter exhaust systems than I have now. Now I have a fairly loud system and no drone, but you definitely hear the car while driving. It's not annoying at all and the sound of the car is really nice.

[Tonester]

We installed an Akra system and we modified the o2 simulators to work. About 100 miles on the system and still no CEL.

Still testing.. we'll keep you posted.

[islandsnow]

Originally Posted by Tonester

We installed an Akra system and we modified the o2 simulators to work. About 100 miles on the system and still no CEL.

Still testing.. we'll keep you posted.

What did you do to the 02 to no throw off the CEL? CEL can take as little as 30 miles to 300 miles

[Tonester]

Originally Posted by islandsnow

What did you do to the 02 to no throw off the CEL? CEL can take as little as 30 miles to 300 miles

It actually depends on drive cycles.

We've been testing and now has many many drive cycles on the car and still no CEL. Generally a bout 4-5 drive cycles the CEL would come on.. but we've had a lot more than that already and still no CEL, looks good so far.

[x838nwy]

Originally Posted by Tonester

We installed an Akra system and we modified the o2 simulators to work. About 100 miles on the system and still no CEL.

Still testing.. we'll keep you posted.

Could you please elaborate on what you mean by "modify" the O2 sensors? I remember seeing a thread about an Akra' system with some kind of miniature cat to install in front of the O2. Is this what you're using?

Thanks

[askiles]

Originally Posted by x838nwy

Could you please elaborate on what you mean by "modify" the O2 sensors? I remember seeing a thread about an Akra' system with some kind of miniature cat to install in front of the O2. Is this what you're using?

Thanks

No, that is the O2 simulator that he is talking about, that they modified. It goes in the second O2 bung, not the first one. It actually acts as a catalytic converter for the sensor. It is a great idea, it just does not work on US spec cars yet. Soon hopefully.

-Andy

[Tonester]

Originally Posted by askiles

No, that is the O2 simulator that he is talking about, that they modified. It goes in the second O2 bung, not the first one. It actually acts as a catalytic converter for the sensor. It is a great idea, it just does not work on US spec cars yet. Soon hopefully.

-Andy

Correct, except for that we have it working in a US Spec vehicle.

Out of the box they do not work with a US Spec vehicle.. but we've modified them so that they work w/ US Spec vehicles.

We've made these types of simulators work on all types of cars... Lambo's, BMW's, Porsche's.

[x838nwy]

Originally Posted by Tonester

Correct, except for that we have it working in a US Spec vehicle.

Out of the box they do not work with a US Spec vehicle.. but we've modified them so that they work w/ US Spec vehicles.

We've made these types of simulators work on all types of cars... Lambo's, BMW's, Porsche's.

Cool

So, just so I can get my noob head around this - the simulator works out of the box on Euro spec cars, but not the US?

So, you mean that if I were to install an Akrapovic full system, all I need is the simulators (or two of them) in front of the O2 sensors and the car will run normally without the CEL?

Cheers.

[sard]

From my personaly experience with the Akrapovic exhaust and my 08 M3, first CEL came on at 37 miles. Second CEL was 90 miles. My third CEL was at 256 miles.

Any idea how things will work for people who have bought the adapters already for US cars? Will they swap out the revised adapters if they do in fact work for free?

[BMW-Motorsport]

Originally Posted by Tonester

Correct, except for that we have it working in a US Spec vehicle.

Out of the box they do not work with a US Spec vehicle.. but we've modified them so that they work w/ US Spec vehicles.

We've made these types of simulators work on all types of cars... Lambo's, BMW's, Porsche's.

Are these the adaptors which "Checkcaptain" is providing with his systems?
I already have more than 500 mls on it without CEL.

[sard]

Originally Posted by mixja

Thanks for the feedback, yeah resonance is the better term, it's like the sound you get when blowing across the top of a bottle.

I can hear it in your video with the windows rolled up, at the beginning of the video with one of the downshifts and then slightly as you accelerate away from the first corner in the video. But it doesn't sound like it's too bad.

The easiest way to test for it is to drive along in 6th or 7th gear at 2000RPM and go WOT. You will definitely hear if there are is any resonance. When I had AA HFC down pipes with factory exhaust, it was quite bad at several RPM points (2000, 2500, 4000).

Ok, I was listening for the drone today, it definitely drones. It's not too bad though. Also it's a higher pitched drone....not the deep bass type.

[mixja]

Originally Posted by sard

Ok, I was listening for the drone today, it definitely drones. It's not too bad though. Also it's a higher pitched drone....not the deep bass type.

Bugger, on my previous car (RS4) I had a full Milltek system and it only had drone around 1500RPM which was OK as I never drove in that RPM range.

Whereabouts in terms of RPM do you hear the drone?

[sard]

Originally Posted by mixja

Bugger, on my previous car (RS4) I had a full Milltek system and it only had drone around 1500RPM which was OK as I never drove in that RPM range.

Whereabouts in terms of RPM do you hear the drone?

I didn't listen that closely, but when I glanced at the rpm it was at 2500, I'm not sure the exact range though.

[Cloud]

Originally Posted by BMW-Motorsport

Are these the adaptors which "Checkcaptain" is providing with his systems?
I already have more than 500 mls on it without CEL.

I thought you mentioned somewhere that there CEL never came up for 2k miles?

Were the ones u have bonalumes?

[BMW-Motorsport]

Originally Posted by Cloud

I thought you mentioned somewhere that there CEL never came up for 2k miles?

Were the ones u have bonalumes?

You´re right, thanks - the "2" was not taken! It´s 2500+ miles for now.
No it was not bonalume, guess it was his own adaptor, but it works so far.
What adaptors do you have? Do they work?

[Cloud]

Were the ones he gave you completely sealed off?

I have 100+ miles on mine and no CEL yet. We'll see when I get back the car today.

[Tonester]

Originally Posted by x838nwy

Cool

So, just so I can get my noob head around this - the simulator works out of the box on Euro spec cars, but not the US?

So, you mean that if I were to install an Akrapovic full system, all I need is the simulators (or two of them) in front of the O2 sensors and the car will run normally without the CEL?

Cheers.

Not any simulator will work. Thats why we reworked them to be compatible.

[BMW-Motorsport]

Originally Posted by Tonester

Not any simulator will work. Thats why we reworked them to be compatible.

Hey Tonester,
no answer is also an answer! So I do assume that you are just working with Ralf´s modified adaptors also. Guess his ones are pretty reliable, or should I doublecheck if I have a Eurospec car

[BMW-Motorsport]

Originally Posted by Cloud

Were the ones he gave you completely sealed off?

I have 100+ miles on mine and no CEL yet. We'll see when I get back the car today.

I did not install them - a friend did this for me, so I can´t tell.

[Trier Germany]

The lamda adapters on the European cars still cause CEL with the Akra system. I have a friend that expierences the CEL. His performance shop is trying a modified adapter that adds some length to o2 sim. I just think th U.S. spec ECU is set up a tad more sensitive for emissions.