[DoZZa]

Had the running in service done and the MPE installed a couple of days ago.

As you know, I can now take the engine above 5.5krpm.

I have been noticing a strange noise coming from the rear of the car under full load and above 6krpm. It sounds like a howling type noise.

Only occurs above 6krpm.

Anyone else notice this noise at this engine speed?

Could it just be the exhaust or possibly the diff?

Noise occurs with the exhaust valves opened or closed.

[430409M2]

The MPE has a drone that'll harmonize with the chassis of the car within a particular band of RPM's. But that is usually lower in the rev range, like 3.5k to 4.5k roughly. I've also experienced quite a lot of turbo noise, both whistling under load or coming to idle.

Off the top of my head, I don't recall 6k having a noticeable new sound being made, but I'll look for it in a little when I drive again.

My first instinct when hearing that a inline-6 engine is howling, without any further infomation, is to say that it is normal. There's even a well known howl (from a flat-6) called the Porsche howl. RIP Porsche howl.

[DoZZa]

Its a pretty smart sound, it doesn't sound like something is wrong. Just didnt expect to hear it. Ill try and get a sound clip somehow.

[Endeav]

I know exactly what sound you're talking about! It actually came up a week ago at a track day and a couple of us came to the conclusion that the carbon fiber tips on the MPE make a howling sound at high(er) speeds just by nature of how the air passes over them.

It's definitely a very loud howl - almost sounds like a blown turbo but from the rear of the vehicle. The only M2 at track day that didn't make this sound was the one without the MPE.

[cookiesowns]

I have the MPE with ASD codes off and regular titanium tips no CF and I get the howl under full load.

I think it’s just the wastegate dumping excess boost due to less backpressure of the MPE in Track mode. No idea if the regular M2’s have it. With ASD codes off you def hear it more

I don’t mind the sound as long as it doesn’t mean there’s a boost leak

[stefan]

Just wanted to chime in that I have this too with MPE.

[GregoryK]

I have a howling noise and drove another car and it has it too. I think mine is the diff.
I have a stick and you can make it do it at lower revs (3k and up) by feathering the clutch under power. These diffs are super noisy.

[Orchard6]

Have you checked that the prostitute in the rolled up carpet in the boot that you thought you had killed is actually dead?

[Fear-Mongrel]

Originally Posted by Orchard6

Have you checked that the prostitute in the rolled up carpet in the boot that you thought you had killed is actually dead?

On the one hand, this response may trigger some people. On the other, the fact that the trunk is so roomy really does speak to the practicality of this car.

[DoZZa]

I didn't update this thread. But the howling sound is only apparent when the exhaust valves are closed. When open, there is no sound.