DIY Video: Disconnecting Exhaust Valves
12-14-2014, 09:15 PM
#16
Nordschleife Master
Not saying my butt dyno is better than yours but FWIW, I felt that torque in the low rev range was diminished when I did this mod and posted a DIY (not as nicely done as yours) about it a couple of months ago. I ended up switching things back. BTW, I used wire instead of plastic to tie things off because of the heat involved in that area.
The PSE is fairly sophisticated and IMO simply blocking the vacuum source negates some of the other features built into the system. For anyone who is interested, this is what the Porsche tech intro docs have to say about it. Regardless, well done vid and beautiful car!
Switchable exhaust flaps
Like its predecessor, the 911 GT3 (991) has a function for increasing torque in the
middle rpm range. This function is not activated by pressing a SPORT button as was
the case for the previous model, but instead using the button with the twin tailpipe
symbol (1) in the center console. When this button is pressed, the torque is
increased in the middle rpm range. The exhaust backpressure in the variable
exhaust system is additionally reduced and the gas cycle is improved, resulting in a
noticeable boost in torque in the rpm range between approximately. 3,000 and
4,000 rpm. The torque levels are increased by between approximately 22 and 26 ft.
lb. (30 and 35 Nm). The maximum torque of 325 ft. lb. (440 Nm) at 6,250 rpm
remains unchanged.
The switching point of the exhaust flaps depends on the load and engine speed. As
on the 997 GT3 II, the switching point from closed to open at full throttle is 3,200
rpm (exhaust flap button (1) pressed) and 4,000 rpm (exhaust flap button (1) not
pressed).
The PSE is fairly sophisticated and IMO simply blocking the vacuum source negates some of the other features built into the system. For anyone who is interested, this is what the Porsche tech intro docs have to say about it. Regardless, well done vid and beautiful car!
Switchable exhaust flaps
Like its predecessor, the 911 GT3 (991) has a function for increasing torque in the
middle rpm range. This function is not activated by pressing a SPORT button as was
the case for the previous model, but instead using the button with the twin tailpipe
symbol (1) in the center console. When this button is pressed, the torque is
increased in the middle rpm range. The exhaust backpressure in the variable
exhaust system is additionally reduced and the gas cycle is improved, resulting in a
noticeable boost in torque in the rpm range between approximately. 3,000 and
4,000 rpm. The torque levels are increased by between approximately 22 and 26 ft.
lb. (30 and 35 Nm). The maximum torque of 325 ft. lb. (440 Nm) at 6,250 rpm
remains unchanged.
The switching point of the exhaust flaps depends on the load and engine speed. As
on the 997 GT3 II, the switching point from closed to open at full throttle is 3,200
rpm (exhaust flap button (1) pressed) and 4,000 rpm (exhaust flap button (1) not
pressed).
Some valuable info there Mike. Thanks
12-14-2014, 09:18 PM
#17
Not saying my butt dyno is better than yours but FWIW, I felt that torque in the low rev range was diminished when I did this mod and posted a DIY (not as nicely done as yours) about it a couple of months ago. I ended up switching things back. BTW, I used wire instead of plastic to tie things off because of the heat involved in that area.
The PSE is fairly sophisticated and IMO simply blocking the vacuum source negates some of the other features built into the system. For anyone who is interested, this is what the Porsche tech intro docs have to say about it. Regardless, well done vid and beautiful car!
Switchable exhaust flaps
Like its predecessor, the 911 GT3 (991) has a function for increasing torque in the
middle rpm range. This function is not activated by pressing a SPORT button as was
the case for the previous model, but instead using the button with the twin tailpipe
symbol (1) in the center console. When this button is pressed, the torque is
increased in the middle rpm range. The exhaust backpressure in the variable
exhaust system is additionally reduced and the gas cycle is improved, resulting in a
noticeable boost in torque in the rpm range between approximately. 3,000 and
4,000 rpm. The torque levels are increased by between approximately 22 and 26 ft.
lb. (30 and 35 Nm). The maximum torque of 325 ft. lb. (440 Nm) at 6,250 rpm
remains unchanged.
The switching point of the exhaust flaps depends on the load and engine speed. As
on the 997 GT3 II, the switching point from closed to open at full throttle is 3,200
rpm (exhaust flap button (1) pressed) and 4,000 rpm (exhaust flap button (1) not
pressed).
The PSE is fairly sophisticated and IMO simply blocking the vacuum source negates some of the other features built into the system. For anyone who is interested, this is what the Porsche tech intro docs have to say about it. Regardless, well done vid and beautiful car!
Switchable exhaust flaps
Like its predecessor, the 911 GT3 (991) has a function for increasing torque in the
middle rpm range. This function is not activated by pressing a SPORT button as was
the case for the previous model, but instead using the button with the twin tailpipe
symbol (1) in the center console. When this button is pressed, the torque is
increased in the middle rpm range. The exhaust backpressure in the variable
exhaust system is additionally reduced and the gas cycle is improved, resulting in a
noticeable boost in torque in the rpm range between approximately. 3,000 and
4,000 rpm. The torque levels are increased by between approximately 22 and 26 ft.
lb. (30 and 35 Nm). The maximum torque of 325 ft. lb. (440 Nm) at 6,250 rpm
remains unchanged.
The switching point of the exhaust flaps depends on the load and engine speed. As
on the 997 GT3 II, the switching point from closed to open at full throttle is 3,200
rpm (exhaust flap button (1) pressed) and 4,000 rpm (exhaust flap button (1) not
pressed).
Thanks Mike. This pretty much solidifies that I will put it back together.
12-14-2014, 09:45 PM
#18
I did it quite a while ago. I simply don't care what I lose in the middle range.
Car has pretty much no power below 4000 rpm anyway.
I just keep my rev range upper than 4000 all the time using low gears.
I do this valve thing to all of my cars either bmw or p car or f car or l car.
Just rev it high and keep valve open all time is more fun to me, much clean exhaust notes and sound matchs rpm.
Car has pretty much no power below 4000 rpm anyway.
I just keep my rev range upper than 4000 all the time using low gears.
I do this valve thing to all of my cars either bmw or p car or f car or l car.
Just rev it high and keep valve open all time is more fun to me, much clean exhaust notes and sound matchs rpm.
12-14-2014, 09:48 PM
#19
For OP.
Good job of showing us what it takes.
One thing I want to add is, if you can plug the thing with rubber scrap or plastic scraps and put it back on to the valve it should be no concern of melting strap or vaccum line moving around.
Good job of showing us what it takes.
One thing I want to add is, if you can plug the thing with rubber scrap or plastic scraps and put it back on to the valve it should be no concern of melting strap or vaccum line moving around.
12-14-2014, 09:50 PM
#20
Nordschleife Master
I did it quite a while ago. I simply don't care what I lose in the middle range.
Car has pretty much no power below 4000 rpm anyway.
I just keep my rev range upper than 4000 all the time using low gears.
I do this valve thing to all of my cars either bmw or p car or f car or l car.
Just rev it high and keep valve open all time is more fun to me, much clean exhaust notes and sound matchs rpm.
Car has pretty much no power below 4000 rpm anyway.
I just keep my rev range upper than 4000 all the time using low gears.
I do this valve thing to all of my cars either bmw or p car or f car or l car.
Just rev it high and keep valve open all time is more fun to me, much clean exhaust notes and sound matchs rpm.
But do you use an after market exhaust bi-pass similar to the SW?
12-14-2014, 10:01 PM
#21
Race Director
I did it quite a while ago. I simply don't care what I lose in the middle range.
Car has pretty much no power below 4000 rpm anyway.
I just keep my rev range upper than 4000 all the time using low gears.
I do this valve thing to all of my cars either bmw or p car or f car or l car.
Just rev it high and keep valve open all time is more fun to me, much clean exhaust notes and sound matchs rpm.
Car has pretty much no power below 4000 rpm anyway.
I just keep my rev range upper than 4000 all the time using low gears.
I do this valve thing to all of my cars either bmw or p car or f car or l car.
Just rev it high and keep valve open all time is more fun to me, much clean exhaust notes and sound matchs rpm.
If you plan to plug the vacuum line with "scrap" in the line itself make sure it's secure. The spring on the flapper valve is quite stiff and requires some pretty strong suction to overcome it. I'd hate to think of rubber or plastic scrap being sucked into the intake.
12-14-2014, 10:41 PM
#22
Racer
I am going to try this mod this week. I ordered some thin galvanized wire and some rubber caps from JEGS to plug the valve itself. I was planning to remove the rubber mid section between the vac line and the valve but it seems leaving that on like you did in the video is a more wise choice in case I want to revert back to stock quickly. Unless I feel a noticeable difference in low end torque I will probably prefer a growl throughout the rpm range. I like my cars loud, drone does not bother me that much unless it is really really bad 
I did this on 2 F cars and was much more happy with the same sound throughout the rpm range.
Worst case I switch it back in 10 minutes…..
I did this on 2 F cars and was much more happy with the same sound throughout the rpm range.
Worst case I switch it back in 10 minutes…..
12-14-2014, 10:59 PM
#23
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if youre always above 4000 rpm, then you shouldnt need this mod to begin with?, since the valves are always open at that rpm...
12-14-2014, 11:03 PM
#24
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good vid.
yeah it would be nice if you could have an option that keeps them open no matter what, and then another option that keeps them off. then you could decide based on wether you want the low end torque, or you just want the sound(which for me would be all the time), even if i sacrifice a bit of torque.
i dont think a little drone would bother me, after all thats what were going for isnt it? more sound?
yeah it would be nice if you could have an option that keeps them open no matter what, and then another option that keeps them off. then you could decide based on wether you want the low end torque, or you just want the sound(which for me would be all the time), even if i sacrifice a bit of torque.
i dont think a little drone would bother me, after all thats what were going for isnt it? more sound?
12-14-2014, 11:18 PM
#25
Nordschleife Master
are those hose spring clamps on the valves ? If so, one of these locking spring clamp pliers or tools may be handy.
tool for tough to reach places...
http://www.tooltopia.com/otc-tools-4...FbBm7AodnlAAFA
plier type when reach isn't an issue
http://www.tooltopia.com/kd-tools-3975.aspx
tool for tough to reach places...
http://www.tooltopia.com/otc-tools-4...FbBm7AodnlAAFA
plier type when reach isn't an issue
http://www.tooltopia.com/kd-tools-3975.aspx
12-15-2014, 02:31 AM
#26
bronson7- no just unpluged and that is all. I just unplug cars and leave as is in case some happens so that I have to put back on again to find what is wrong, which is the case with L cars alot....
mainly- Yes it is of no use if I keep above 4000 most of time. but stop and go and drop in rpm triggers inconsistant sounds, so I open the valves. also, low rpm lift creates bubbling sound when you do this mod. it is more fun to listen to...v12 ferraris(even v8 ferraris) are at best of this so whenever I get new cars I do this on PDI stage.
What I found interesting is, on F cars, you have to give at least 5000 kms of running before judging how loud it has become weither to shut it again. It gets sometimes annoyingly loud. I am not sure about P cars but gt3 sound has become louder since the mod after about 2000 kms.
mainly- Yes it is of no use if I keep above 4000 most of time. but stop and go and drop in rpm triggers inconsistant sounds, so I open the valves. also, low rpm lift creates bubbling sound when you do this mod. it is more fun to listen to...v12 ferraris(even v8 ferraris) are at best of this so whenever I get new cars I do this on PDI stage.
What I found interesting is, on F cars, you have to give at least 5000 kms of running before judging how loud it has become weither to shut it again. It gets sometimes annoyingly loud. I am not sure about P cars but gt3 sound has become louder since the mod after about 2000 kms.
12-15-2014, 03:49 AM
#28
When this button is pressed, the torque is increased in the middle rpm range. The exhaust backpressure in the variable exhaust system is additionally reduced and the gas cycle is improved, resulting in a noticeable boost in torque in the rpm range between approximately. 3,000 and 4,000 rpm. The torque levels are increased by between approximately 22 and 26 ft. lb. (30 and 35 Nm). The maximum torque of 325 ft. lb. (440 Nm) at 6,250 rpm remains unchanged.
Below 4,000 rpm the torque curve is flatter on the graph (provided by Porsche on GT3 launch) then it spikes up after 4,000. As it is suggesting in the literature from Porsche, back pressure is reduced at 4,000 rpm when the valves open, thus giving more torque. Generally, as far as I'm aware, when there is less back pressure in the exhaust (more flow) the engine puts out more torque, at lower rpm. The only time the engine needs some back pressure is at the higher rpms to keep up that compression. So maybe having the exhaust open all the time at lower rpm would provide better torque between 1,000 - 4,000? Obviously I would have to try it in person to see the difference.
12-15-2014, 04:16 AM
#29
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Not saying my butt dyno is better than yours but FWIW, I felt that torque in the low rev range was diminished when I did this mod and posted a DIY (not as nicely done as yours) about it a couple of months ago. I ended up switching things back. BTW, I used wire instead of plastic to tie things off because of the heat involved in that area.
The PSE is fairly sophisticated and IMO simply blocking the vacuum source negates some of the other features built into the system. For anyone who is interested, this is what the Porsche tech intro docs have to say about it. Regardless, well done vid and beautiful car!
Switchable exhaust flaps
Like its predecessor, the 911 GT3 (991) has a function for increasing torque in the
middle rpm range. This function is not activated by pressing a SPORT button as was
the case for the previous model, but instead using the button with the twin tailpipe
symbol (1) in the center console. When this button is pressed, the torque is
increased in the middle rpm range. The exhaust backpressure in the variable
exhaust system is additionally reduced and the gas cycle is improved, resulting in a
noticeable boost in torque in the rpm range between approximately. 3,000 and
4,000 rpm. The torque levels are increased by between approximately 22 and 26 ft.
lb. (30 and 35 Nm). The maximum torque of 325 ft. lb. (440 Nm) at 6,250 rpm
remains unchanged.
The switching point of the exhaust flaps depends on the load and engine speed. As
on the 997 GT3 II, the switching point from closed to open at full throttle is 3,200
rpm (exhaust flap button (1) pressed) and 4,000 rpm (exhaust flap button (1) not
pressed).
The PSE is fairly sophisticated and IMO simply blocking the vacuum source negates some of the other features built into the system. For anyone who is interested, this is what the Porsche tech intro docs have to say about it. Regardless, well done vid and beautiful car!
Switchable exhaust flaps
Like its predecessor, the 911 GT3 (991) has a function for increasing torque in the
middle rpm range. This function is not activated by pressing a SPORT button as was
the case for the previous model, but instead using the button with the twin tailpipe
symbol (1) in the center console. When this button is pressed, the torque is
increased in the middle rpm range. The exhaust backpressure in the variable
exhaust system is additionally reduced and the gas cycle is improved, resulting in a
noticeable boost in torque in the rpm range between approximately. 3,000 and
4,000 rpm. The torque levels are increased by between approximately 22 and 26 ft.
lb. (30 and 35 Nm). The maximum torque of 325 ft. lb. (440 Nm) at 6,250 rpm
remains unchanged.
The switching point of the exhaust flaps depends on the load and engine speed. As
on the 997 GT3 II, the switching point from closed to open at full throttle is 3,200
rpm (exhaust flap button (1) pressed) and 4,000 rpm (exhaust flap button (1) not
pressed).
So I guess it is possible that some maybe minimal amount of TQ is lost at lower rpm ranges when the valves are kept always at the open position.
Last edited by UAEGT3; 12-15-2014 at 05:26 AM.
