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Can anyone point me to a technical description of how the 991.1 Sport Exhaust System works?
I know. Push the button. It lights up. Things get louder and gurgly. That's how you actuate it.
I'd like to understand how it works. I recall reading somewhere that fuel was being sprayed on some hot bit, but I don't know if that was fact or fantasy. I wish I could find a factory tech article with a cut-away. Something like you'd find in Christophorus
I recall reading somewhere that fuel was being sprayed on some hot bit, but I don't know if that was fact or fantasy.
Two separate things regarding your question. For this one, the DME (if you have Sport Chrono) will over fuel on throttle lift, and that's how/where you get the snaps, crackles, pops & gurgles with PSE.
I have read this "over fuel" comment countless times. But I find it hard to believe that this would be permissible by the EPA for environmental and fuel consumption reasons. We have start stop tech and coasting feature to meet EPA requirements but dumping extra fuel every time you let up on the gas is just fine? Hard to believe. Anyone with a verified source of facts for this?
I have read this "over fuel" comment countless times. But I find it hard to believe that this would be permissible by the EPA for environmental and fuel consumption reasons. We have start stop tech and coasting feature to meet EPA requirements but dumping extra fuel every time you let up on the gas is just fine? Hard to believe. Anyone with a verified source of facts for this?
My guess is EPA only cares about the "normal" case of driving (ie cruising speed, cold start etc etc.) i dont think they care much about the when the gas is lifted and that 1sec would spill out extra gas.
My guess is EPA only cares about the "normal" case of driving (ie cruising speed, cold start etc etc.) i dont think they care much about the when the gas is lifted and that 1sec would spill out extra gas.
think about how smog tests are done.....
Just my guess....i could be completely wrong
You are completely wrong. During the EPA certification, the cars are tested on five different driving cycles, all of which have accelerations, decelerations, with plenty of throttle emotion. But I suspect that cars are tested in NORMAL mode, if the car always starts in that mode. If you can lock it to start in SPORT mode as well, then it is probably tested in both modes with the results averaged. State emissions tests are trivially simple in comparison.
I don't know how the exhaust popping is generated, but adding extra fuel alone won't do it, as there is no excess oxygen in the exhaust to burn the fuel. Does anyone know how it is done?
On my RX-7, on throttle lift, you could program the ECU to turn the injectors back on during decel. They would start to dump fuel which would ignite in the hot exhaust shooting flames.
Depending on how you tune (not for efficiency) the car you can have the fuel be injected and it will ignite in the exhaust making LOUD popping sounds.
Suspect it will be something similar in the Porsche.
I already answered in post #2, yesterday. What is your answer/explanation, Jim? I would very much enjoy reading it.
This information has been covered in old issues of Panorama, just to name one source. Also from race shops like BGB in Florida.
The system is activated by the switch on the consul. This switch activates via the vacuum system to two valves in the exhaust pathway that redirects the exhaust more directly out the tail pipe. No Your picture still does NOTHING to show how easily extra fuel is added. Yes extra fuel is added through the DME but the majority of the sound increase is due to the vacuum controlled valves, not the extra fuel that is added.
03-23-2020, 11:43 AM
Sport Exhaust System - How Does It Work
That's how you actuate it.
