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-   -   Exhaust "pop" at redline shift.... normal? (https://xoutpost.com/bmw-sav-forums/x-m-forum/71614-exhaust-pop-redline-shift-normal.html)

TTBear 03-26-2010 04:24 PM

Exhaust "pop" at redline shift.... normal?
 
Thanks, all.

With the nicer weather upon us, we've (OK, I'Ve) had a chance to get on it a little, with some fun 100-240kph runs (on a closed track, naturally.....:p: ).

I'm noticing that when I'm on full throttle, and it's shifting at redline, just as it shifts, I am hearing this little "pop", or "puff", from the exhaust. This happens when I am in "non-M" mode (M button not engaged), and with M button pressed.

I actually think it sounds MEAN, and kinda like it, but just wondering if anyone else is getting it.

BTW - this thing is crazy fast for something that weighs this much!!!

Love it.


thanks everyone.

StumpyPete 03-26-2010 04:35 PM

sounds like a nice bit of turbocharger wastegate overrun to me. But I'll let the others chip in! Good to see you're letting the beast off the leash!

<EDIT> interestingly I then went and looked it up on wikipedia and found this

Wastegate - Wikipedia, the free encyclopedia

Conny4.8iS 03-26-2010 04:46 PM

Quote:

Originally Posted by TTBear (Post 726642)
Thanks, all.

With the nicer weather upon us, we've (OK, I'Ve) had a chance to get on it a little, with some fun 100-240kph runs (on a closed track, naturally.....:p: ).

I'm noticing that when I'm on full throttle, and it's shifting at redline, just as it shifts, I am hearing this little "pop", or "puff", from the exhaust. This happens when I am in "non-M" mode (M button not engaged), and with M button pressed.

I actually think it sounds MEAN, and kinda like it, but just wondering if anyone else is getting it.

BTW - this thing is crazy fast for something that weighs this much!!!

Love it.


thanks everyone.

Thats quite normal and even with shifting at 4.000 and higher in manual or with m-mode y'll get the chance to hear it. Thats a special programming by BMW for the exhausts. Enjoy :thumbup:

///MB 03-26-2010 07:21 PM

Yup, totally normal. I hear it at almost every shift. :-p

jst2878 03-27-2010 06:34 PM

blow offs on the wastegate

TTBear 03-28-2010 03:12 AM

Thanks for the comments, everyone.

Good to know.

And yes, I am lovin' it :)

JCL 03-28-2010 12:52 PM

Quote:

Originally Posted by jst2878 (Post 726925)
blow offs on the wastegate

Why would the wastegates change with a shift (on the exhaust side of the turbo)? Wouldn't it more likely be a pressure wave on the compressor side?

jimsaq 03-28-2010 06:23 PM

yep I hear this quite a bit under heavier acceleration when changing gear at higher rpm
love it

Nic941 03-28-2010 06:30 PM

The Burp.

Love the truck!

K

998M 03-29-2010 09:42 AM

No idea what it is but I hear it. Also, nothing better than that great sound when you let off the throttle at higher RPM with M on. Just terrific.


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