I Need Everyone's Help that Cares About Our Exhaust
03-19-2015, 02:48 AM
#61
Burning Brakes
This should be pretty interesting. I have a feeling it'll be a good combination with the lighter side mufflers and the Sharkwerks bypass. I wish I could remember where I saw it, but I believe I saw in a 997 GT3/RS exhaust thread, that the side muffler delete actually slightly lost power over stock in most ranges, but provided the best sound, whereas the center muffler delete didn't sound quite as good as the side muffler delete, but definitely sounded better than Stock and didnt lose any power, maybe a small gain even, but if any gains, it was minimal. That's just going from memory though.
03-19-2015, 08:04 AM
#62
Rennlist Member
Matt, how did you override the valve? Is it a tie-off like on other platforms? I might be okay with just removing the valve function for now.
I'm less and less interested in the center muffler delete, as the only exhaust mod. It's all or nothing for me at this point.
I'm less and less interested in the center muffler delete, as the only exhaust mod. It's all or nothing for me at this point.
03-19-2015, 08:23 AM
#63
Closed Valves = Less Exhaust Flow which = Less Power and Torque.
Open Valves = More Exhaust Flow which = More Power and Torque.
I have proven this. This is not a theory. Your tech doesn't know what he is talking about.
Why in the world would more back pressure allow for more torque at any RPM?
Open Valves = More Exhaust Flow which = More Power and Torque.
I have proven this. This is not a theory. Your tech doesn't know what he is talking about.
Why in the world would more back pressure allow for more torque at any RPM?
Directly from our GT3 owner's manual, page 146:
Sports Exhaust System
"When the sports exhaust system is switched on, the exhaust back pressure in the lower and middle rpm ranges is reduced in the variable exhaust system. This produces a noticeable increase in torque in the engine speed range between approx. 3,000 and 4,000 rpm. This does not change the maximum torque of 324 ftlb. (440 Nm) at 6,250 rpm."
Hence, why for street driving the loss of torque, as stated above and in my initial reply, will be noticeable. It was on the last car and will be on the 991.
Under full throttle, the valves are fully open, delivering the same peak torque.
Maybe Porsche doesn't know what they are talking about either.
To answer your last question above: exhaust velocity effects torque at particular rpms, load and throttle applications.
Last edited by 911dev; 03-19-2015 at 08:59 AM.
03-19-2015, 08:57 AM
#64
Burning Brakes
My information is not only from the tech., nor only from the quoted manual below. Anyway, for the record, more flow does always equate to more torque.
Directly from our GT3 owner's manual, page 146:
Sports Exhaust System
When the sports exhaust system is switched on, the exhaust back pressure in the lower and middle rpm ranges is reduced in the variable exhaust system. This produces a noticeable increase in torque in the engine speed range between approx. 3,000 and 4,000 rpm. This does not change the maximum torque of 324 ftlb. (440 Nm) at 6,250 rpm.
Hence, why for street driving the loss of torque, as stated above and in my initial reply, will be noticeable. It was on the last car and will be on the 991.
Under full throttle, the valves are fully open, delivering the same peak torque.
Maybe Porsche doesn't know what they are talking about either.
To answer your last question above: exhaust velocity effects torque at particular rpms.
Directly from our GT3 owner's manual, page 146:
Sports Exhaust System
When the sports exhaust system is switched on, the exhaust back pressure in the lower and middle rpm ranges is reduced in the variable exhaust system. This produces a noticeable increase in torque in the engine speed range between approx. 3,000 and 4,000 rpm. This does not change the maximum torque of 324 ftlb. (440 Nm) at 6,250 rpm.
Hence, why for street driving the loss of torque, as stated above and in my initial reply, will be noticeable. It was on the last car and will be on the 991.
Under full throttle, the valves are fully open, delivering the same peak torque.
Maybe Porsche doesn't know what they are talking about either.
To answer your last question above: exhaust velocity effects torque at particular rpms.
03-19-2015, 09:00 AM
#65
Rennlist Member
Thread Starter
It takes about 5 minutes, so it's worth a try to see if you like it.
03-19-2015, 09:03 AM
#66
On page 34 of the service manual it states that pressing the twin tailpipe button " torque is increased in the middle RPM range. The exhaust back pressure is reduced and gas cycle improved, resulting in a noticeable bossy in torque in the RPM range between 3000-4000. The torque levels are increased by approximately 22 and 26 ft lb. Maximum torque remains unchanged".
Not sure if you're agreeing or disputing. Either way, it affirms what I posted.
I think what some people are getting confused about is the assumption when pressing the exhaust button opens the valves fully to attain increased torque. That is not the case, if it was eliminating them would yield the same result mid range. Torque IS increased in the mid because of the variable effect of the valves. They close partially to reduce back pressure at particular rpms, load and throttle input, as to increase mid torque. At full throttle they are fully open yielding identical peak torque.
03-19-2015, 09:07 AM
#67
Burning Brakes
03-19-2015, 09:11 AM
#68
Rennlist Member
Thread Starter
My information is not only from the tech., nor only from the quoted manual below. Anyway, for the record, more flow does always equate to more torque.
Directly from our GT3 owner's manual, page 146:
Sports Exhaust System
"When the sports exhaust system is switched on, the exhaust back pressure in the lower and middle rpm ranges is reduced in the variable exhaust system. This produces a noticeable increase in torque in the engine speed range between approx. 3,000 and 4,000 rpm. This does not change the maximum torque of 324 ftlb. (440 Nm) at 6,250 rpm."
Hence, why for street driving the loss of torque, as stated above and in my initial reply, will be noticeable. It was on the last car and will be on the 991.
Under full throttle, the valves are fully open, delivering the same peak torque.
Maybe Porsche doesn't know what they are talking about either.
To answer your last question above: exhaust velocity effects torque at particular rpms, load and throttle applications.
Directly from our GT3 owner's manual, page 146:
Sports Exhaust System
"When the sports exhaust system is switched on, the exhaust back pressure in the lower and middle rpm ranges is reduced in the variable exhaust system. This produces a noticeable increase in torque in the engine speed range between approx. 3,000 and 4,000 rpm. This does not change the maximum torque of 324 ftlb. (440 Nm) at 6,250 rpm."
Hence, why for street driving the loss of torque, as stated above and in my initial reply, will be noticeable. It was on the last car and will be on the 991.
Under full throttle, the valves are fully open, delivering the same peak torque.
Maybe Porsche doesn't know what they are talking about either.
To answer your last question above: exhaust velocity effects torque at particular rpms, load and throttle applications.
On page 34 of the service manual it states that pressing the twin tailpipe button " torque is increased in the middle RPM range. The exhaust back pressure is reduced and gas cycle improved, resulting in a noticeable bossy in torque in the RPM range between 3000-4000. The torque levels are increased by approximately 22 and 26 ft lb. Maximum torque remains unchanged".
I did notice a bit more power sooner with the valve connected and PSE On, indicating that the valves are open sooner, creating more flow.
So my conclusion is that, yes the PSE button does something to overcome the lack of flow with the valves closed to ensure there isn't a loss in torque. But if you take the valves opening and closing out of the equation, you get more torque and power.
I think there is a misinterpretation of what the manual is telling us about the PSE. Because the valves are closed, the computer must adjust to ensure there isn't a huge loss in torque. Open the valves and you're better off.
I wouldn't be so dug in on this if I had spend an entire day testing and analyzing. Sometimes techs just throw crap out there never having any actual experience.
03-19-2015, 09:34 AM
#69
That's why I tested PSE On and Off with the valves disconnected to see if PSE button adjusted anything outside of the valve control. I concluded that if it does, it doesn't do much. It seems clear to me that with the valves closed the DME/ECU needs to perform some adjustments to overcome the lack of exhaust flow. Under WOT or moderate throttle there was a much more linear, smoother torque and horsepower curve with the valves taken out of the equation.
I did notice a bit more power sooner with the valve connected and PSE On, indicating that the valves are open sooner, creating more flow.
So my conclusion is that, yes the PSE button does something to overcome the lack of flow with the valves closed to ensure there isn't a loss in torque. But if you take the valves opening and closing out of the equation, you get more torque and power.
I think there is a misinterpretation of what the manual is telling us about the PSE. Because the valves are closed, the computer must adjust to ensure there isn't a huge loss in torque. Open the valves and you're better off.
I wouldn't be so dug in on this if I had spend an entire day testing and analyzing. Sometimes techs just throw crap out there never having any actual experience.
I did notice a bit more power sooner with the valve connected and PSE On, indicating that the valves are open sooner, creating more flow.
So my conclusion is that, yes the PSE button does something to overcome the lack of flow with the valves closed to ensure there isn't a loss in torque. But if you take the valves opening and closing out of the equation, you get more torque and power.
I think there is a misinterpretation of what the manual is telling us about the PSE. Because the valves are closed, the computer must adjust to ensure there isn't a huge loss in torque. Open the valves and you're better off.
I wouldn't be so dug in on this if I had spend an entire day testing and analyzing. Sometimes techs just throw crap out there never having any actual experience.
03-19-2015, 10:08 AM
#72
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Porsche 991 GT3 with CargraphicTS Exhaust Kit 6 great sound - YouTube
This one from cargraphic looks and sounds pretty good. Maybe a group buy to get the cost down
This one from cargraphic looks and sounds pretty good. Maybe a group buy to get the cost down
1.) If you are interested in the system that is comparable to what is being discussed (center muffler delete & upgraded side mufflers) I would offer the kit for 10% off MSRP, excluding FedEx shipping/customs. That kit retails for $4995. The FVD unit is $2200 and the addition of the Sharkwerks unit @ $1500 would be $3700 so compared to what is being discussed, the additional price of the Cargraphic Lighweight Exhaust Kit #1 would be the electronics to hook up the valves.
2.) We would eat any and all costs over the typical 3 - 4 hours to install; this means we would spend time on our own nickel hooking up any flaps, etc. and revising any DME coding to deactivate flaps (see #6).
3.) If for any reason you were not happy, I would remove the system for free and return your car as delivered. The customer would be required to re-sell the used Cargraphic unit but I have yet to have anyone return a Cargraphic part from a race or street car since 2009.
4.) We would dyno the car before and after and offer to split these costs 50/50 with you. It's $120 per hour for the dyno and 1 hour for our time so $220 to do a before and $220 to do an after, of which we would eat half.
5.) IF we had enough parties, a 10% group buy would go into effect provided you guys liked what you saw.
6.) If you want your valves disconnected to work WITHOUT input from the DME, we sat around last night and I made a call or two to some friends in Germany and we discussed how we could achieve this via plumbing of the vacuum lines AND coding in the DME. Some people don't like the valve activation but I would assume some of you want it for keeping noise levels down in urban areas or on tracks with super stringent sound DB levels.
This is all that I can offer at this moment. Realizing how much you guys want data, the above concessions would be offered to someone interested in the project looking to document the entire thing. NateOz knows how much we like the Cargraphic stuff so if anyone who has expressed interest in Cargraphic, please PM me. This project wasn't even on our radar til the OP called several times yesterday stating how many units we would be able to sell if successful. Given their quick shift in direction to FVD, I'm chiming in to continue to keep the Cargraphic name in the game; we've been running Cargraphic and FVD on race and street 911s since 2009 so I feel have as much time stress testing these parts as anyone else.
03-19-2015, 10:12 AM
#73
Rennlist Member
Thread Starter
If we have any parties interested in this, I would offer the following concessions to a Florida based 991 GT3 owner:
1.) If you are interested in the system that is comparable to what is being discussed (center muffler delete & upgraded side mufflers) I would offer the kit for 10% off MSRP, excluding FedEx shipping/customs. That kit retails for $4995. The FVD unit is $2200 and the addition of the Sharkwerks unit @ $1500 would be $3700 so compared to what is being discussed, the additional price of the Cargraphic Lighweight Exhaust Kit #1 would be the electronics to hook up the valves.
2.) We would eat any and all costs over the typical 3 - 4 hours to install; this means we would spend time on our own nickel hooking up any flaps, etc. and revising any DME coding to deactivate flaps (see #6).
3.) If for any reason you were not happy, I would remove the system for free and return your car as delivered. The customer would be required to re-sell the used Cargraphic unit but I have yet to have anyone return a Cargraphic part from a race or street car since 2009.
4.) We would dyno the car before and after and offer to split these costs 50/50 with you. It's $120 per hour for the dyno and 1 hour for our time so $220 to do a before and $220 to do an after, of which we would eat half.
5.) IF we had enough parties, a 10% group buy would go into effect provided you guys liked what you saw.
6.) If you want your valves disconnected to work WITHOUT input from the DME, we sat around last night and I made a call or two to some friends in Germany and we discussed how we could achieve this via plumbing of the vacuum lines AND coding in the DME. Some people don't like the valve activation but I would assume some of you want it for keeping noise levels down in urban areas or on tracks with super stringent sound DB levels.
This is all that I can offer at this moment. Realizing how much you guys want data, the above concessions would be offered to someone interested in the project looking to document the entire thing. NateOz knows how much we like the Cargraphic stuff so if anyone who has expressed interest in Cargraphic, please PM me.
1.) If you are interested in the system that is comparable to what is being discussed (center muffler delete & upgraded side mufflers) I would offer the kit for 10% off MSRP, excluding FedEx shipping/customs. That kit retails for $4995. The FVD unit is $2200 and the addition of the Sharkwerks unit @ $1500 would be $3700 so compared to what is being discussed, the additional price of the Cargraphic Lighweight Exhaust Kit #1 would be the electronics to hook up the valves.
2.) We would eat any and all costs over the typical 3 - 4 hours to install; this means we would spend time on our own nickel hooking up any flaps, etc. and revising any DME coding to deactivate flaps (see #6).
3.) If for any reason you were not happy, I would remove the system for free and return your car as delivered. The customer would be required to re-sell the used Cargraphic unit but I have yet to have anyone return a Cargraphic part from a race or street car since 2009.
4.) We would dyno the car before and after and offer to split these costs 50/50 with you. It's $120 per hour for the dyno and 1 hour for our time so $220 to do a before and $220 to do an after, of which we would eat half.
5.) IF we had enough parties, a 10% group buy would go into effect provided you guys liked what you saw.
6.) If you want your valves disconnected to work WITHOUT input from the DME, we sat around last night and I made a call or two to some friends in Germany and we discussed how we could achieve this via plumbing of the vacuum lines AND coding in the DME. Some people don't like the valve activation but I would assume some of you want it for keeping noise levels down in urban areas or on tracks with super stringent sound DB levels.
This is all that I can offer at this moment. Realizing how much you guys want data, the above concessions would be offered to someone interested in the project looking to document the entire thing. NateOz knows how much we like the Cargraphic stuff so if anyone who has expressed interest in Cargraphic, please PM me.
03-19-2015, 10:16 AM
#74
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P.S. If you want us to install that thing and if you want access to my diagnostics that will let you dyno your car on a 2WD Dynojet, that service is still available but at cost.
03-19-2015, 11:56 AM
#75
Race Director
Money - explain to me why with the FVD side mufflers that there are no valves and that the PSE button would be deemed - dead. Are the current valves connected to the OEM side mufflers??