no enjoy the symphony !

 

No.

I have to add this sentence because "no" is too short of a response to be accepted by P-9. lol

 

I think the correct answer is "unknown." The composition of the gases exiting the combustion chambers in a fuel overrun situation has to be different than a normal combustion cycle. The question is what's different? Are the gases more or less corrosive/acidic? Higher or lower temperatures? More or less water vapor? What impact (if any) does the change in pressure when farting have on exhaust components? Over, say, 100,000 miles does a farting car's exhaust system look different that one driven in non-fart mode? Porsche probably knows the answers to all the above, but we don't.

 

The answer is no.

The noise you hear is gasoline combusting in the exhaust system and not the combustion chambers. Normally this is caused by unburnt fuel sneaking out of the cylinder during the exhaust cycle (on older performance cars with less complex ECUs or no direct injection). On the 718 this is the result of extra fuel being added to the exhaust intentionally.

 

Seriously? For the audible effects or otherwise? Doesn't sound like an effective way to improve the fuel mileage requirements.

 

I agree. That is how it's done. Modern FI cars need to "cheat" in order to make that noise. I watched a technical video once from BWM on how they make their cars burble and pop with "additional" overflow from the FI.

 

I must admit, I have often wondered why F1 cars do that what with precision DFI controlling fuel flow. Certainly F1 car designers don't cater to a "need to sound good". Is there possibly another reason for doing that like keeping the turbo spun up or something of that nature?

 

If you misread R Doug's post, he was talking about FI (F-eye, forced induction) not F1 (F-one).

If you mean F1 like Formula 1, if it's done there it's possibly because of sound being missed after the big engine change in 2014 (V10 -> turbo hybrid). See here: https://www.autosport.com/f1/news/121101/f1-engines-to-be-made-louder-in-2016

 

Question: Will long term exposure to these overrun cracks and burbles be harmful to the catalytic converter and/or muffler?

Search on FerrariChat. Looks like they removed the pops on the 458 via software because it was damaging exhaust valves.

Never heard anything about Porsches.

 

FI... fuel injected.

 

I know I'm in the minority here but I'm not a fan of the pops, burbles and such. I like the PSE sound and even the "sound symposer" in my CGTS but I just wish there was an option in the user controls to turn off the pops, etc. in sport mode.

 

My bad. I did misread FI to be F1. Explanations make sense. Thanks.

 

I really should have specified. That's my bad.

 

When you find a way of turning the pops off, please let me know.
I might then think about a new exhaust. I'm running the standard one because the loud pops in PSE really turned me off. The burbles are fine in the standard exhaust and the pops are only just tolerable.

 

If you have the chrono package, the burbles and pops cease in Sport Plus mode (even with PSE engaged). Of course, the traction control also allows for more play in this mode, too.

 

Here's a good read of how Jag does it on the F Type


2014 Jaguar F-Type is calibrated for sonic delight - SAE International

Calibrating a "controlled misfire"

"'Theater' is a great word," noted Kevan Richardson, Program Manager for Jaguar sports cars. “We want the car to be entertaining. That’s why it has pop-up [HVAC] vents, a lighting cascade on start-up and a pop-up rear spoiler. It is all part of the show."

"All of those little noises are usually the kinds of sounds engineers spend months trying to dial out," he acknowledged. "Because this is an unashamed sports car, we’ve recognized the noise the exhaust makes is part of the experience and something customers want."

Jaguar engineers achieved this by defying convention. "Usually you’d cut the fuel to the cylinders, when the driver lifts off the accelerator," explained Andrew Lowis, the Gasoline Calibration Manager for the car. "We are delaying the point when we do that and igniting later than we might in normal circumstances. It produces a controlled misfire."

Obviously, the car must still meet emissions regulations despite the intentional introduction of pollutants to the exhaust stream. "It is a challenge, but it is one we can achieve by careful calibration," said Lowis. In fact, Jaguar has more stringent internal emissions limits than the government applies, he said, and the car meets those, too.

Regardless of the difficulty, it was necessary work, Lowis insisted. "The powertrain sound quality of this car was absolutely fundamental to the character of the F-Type."

The burble through the pipes is made more audible by the use of muffler bypass valves that open to send the glorious noise directly out the back when the driver selects the appropriate drive mode and stands hard on the gas or lifts off abruptly. The bypass is standard equipment on both the V6 S and V8 S, and is an option for the base V6 car.