fast1

OK. In my case the only time I've experienced a variance with similar driving is with temperature. When the exhaust is cold, there is little or no popping. If the exhaust is hot when I aggressively push to redline and abruptly take my foot off the gas pedal, I can guarantee a 4th of July sound effect. And that will happen 100% of the time.

JR956678

The more I have read the more I believe that the specific noises are fake no matter which manufacturer designs them into the vehicle. I have found discussions of this pertaining to Audi (http://www.audiboost.com/content.php...le-this-system and also Jaguar (http://articles.sae.org/12441/). One easy way to get pops and gurgles on overrun is to inject a small amount of fuel late in the exhaust stroke (perhaps also ignited by a late spark in the case of Jaguar). Like Audi, BMW plays a soundtrack through the stereo speakers that is designed to sound like the engine - but it doesn't come from the engine at all. Porsche does it as well; the SoundSymposer (http://articles.sae.org/10374/) is all about piping engine sounds into the cockpit (though in this case it is about engine sounds rather than exhaust sounds). At least in the case of Porsche (maybe all of) this is actual engine sounds rather than an artificial soundtrack - but it remains intentional. I think a Porsche sounds the way it does because it's been carefully engineered to sound that way.

I think in the case of a race car, the sounds are the consequence of tuning for power but in the case of a street car (which has to pass sound and emission standards) the sounds exist because customers want them and not due to the consequence of something else. A case in point is that the 991.1 makes more pops and gurgles in Sport+ mode than it does in Sport mode but the 991.2 makes less noise in Sport+ - the consequence of techniques to reduce turbo lag by keeping gas flow through the turbos at a maximum.

It seems to me that if it's possible to "engineer" sounds into a car it would be possible to engineer them out as well. I think it's a complicated bit of programming to create them and therefore equally complicated to remove them, but I do believe it would be possible.

fast1

I didn't like the popping sounds when I use to race in SCCA events several decades ago, and I especially don't like them when they are contrived. As a matter of fact, I haven't met many people who like the popping sounds. The sound of a well tuned sports car engine running near redline is music to my ears, but the contrived popping sound is just noise as far as I'm concerned.

Needsdecaf

I agree with you there. The harder you push, the more pops.

However, my comment was directed to bardman, who said the pops on his GT4 always followed a specific pattern, as in number and types of pops are always the same. I never hear anything like this.

MagicRat

I love the pops. Re their artificiality, I'm not disputing it but can anyone explain why if you put an aftermarket
can on a bike, as I have done many times, it pops, but the stock exhaust rarely does. All that has changed
is a bit of hardware.

MagicRat

Not sure why my phone formatted previous post like a poem btw!

fast1

Just a guess but it could be that you had the pops before. The aftermarket exhaust amplified the sound and made it were it is easier to hear it within the cabin. The other possibility is that the aftermarket exhaust provides less back pressure, thereby allowing some unburnt fuel to escape before the exhaust valve closes.

MagicRat

Thanks. Second thing makes sense for bikes certainly. Also, I never met a bike person who didn't like overrun sounds, but different strokes for different folks I guess.

911boy

Pops and crackles are way more pronounced in PSE mode as opposed to SPORT &PSE. I LOVE IT!

kayjh

So I ordered my first Porsche on Tuesday and included PSE in the option list. I have been reading the 2017 owners manual in my spare time and came across the car behaviour in various sport chrono modes and found that "backfire" is enabled in sport, but not in normal or sport plus. That would seem to indicate that it is programmed in. I wonder if anyone with PSE can tell us whether the pops are present when in sport plus mode??

Needsdecaf

Your questions have already been answered in this thread. Of course they are programmed in.

Jenner

Page 11:
https://rennlist.com/forums/991/9596...l#post13827560

kayjh

Oops

kayjh

Thanks for the link, but I'm still a bit confused as that post seemed to be dealing with air pumping, etc and the .1 car. Maybe I'm reading it wrong. So do you agree that the pops are absent in S+ with PSE on the .2?

JR956678

991.2 C4S here, and in Sport+ with PSE "on" there are no pops and gurgles; Jenner did a great job in digging out documentation on how and why they have this programming in the .2 car. The .1 car is quite different because there are no turbos thus nothing to be gained by that programming.

You can detect a difference in the engine sounds however and once you realize that they have shut off spark and fuel but kept the throttle open (and presumably the waste gates closed) to keep air flowing through the engine and turbos to reduce turbo lag - you can hear the "pumping" effect.