2011 CTT - typical boost behavior?
10-12-2017, 02:24 PM
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2011 CTT - typical boost behavior?
I latched onto another thread in the 955/957 area about "diverter valves" (aka blow-off valves..) but didn't receive any replies https://rennlist.com/forums/porsche-...audi-710n.html, so I figured maybe a new one in the correct forum specific to the turbo boost performance might be more productive.
First - I live in NJ - so it's rare that I am somewhere that I can actually floor the gas pedal. Traffic and police everywhere just won't permit it. So - there may be some adaptive learning that's gone on with the ECU...
I have the boost gauge up on the MID in the dash. In normal driving it usually is sitting at 0-1PSI. If I dare to mash the pedal for a second - I might see it get as high as 8PSI... about when it reaches there I usually have to slow down for traffic, or are reaching a speed that might draw unwelcome attention.
I think once I saw 15PSI on the gauge. But it's been a while.
I'm questioning if I have tired diverter valves (blow-off valves), and if it would be worth replacing them. The P!G currently has about 75,000 miles on it. People in the other thread appeared to feel that some deterioration was noticeable by that mileage.
So - what's your gauge display under normal driving?
First - I live in NJ - so it's rare that I am somewhere that I can actually floor the gas pedal. Traffic and police everywhere just won't permit it. So - there may be some adaptive learning that's gone on with the ECU...
I have the boost gauge up on the MID in the dash. In normal driving it usually is sitting at 0-1PSI. If I dare to mash the pedal for a second - I might see it get as high as 8PSI... about when it reaches there I usually have to slow down for traffic, or are reaching a speed that might draw unwelcome attention.
I think once I saw 15PSI on the gauge. But it's been a while.
I'm questioning if I have tired diverter valves (blow-off valves), and if it would be worth replacing them. The P!G currently has about 75,000 miles on it. People in the other thread appeared to feel that some deterioration was noticeable by that mileage.
So - what's your gauge display under normal driving?
10-12-2017, 10:33 PM
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Meanwhile - anyone have boost numbers to post?
10-13-2017, 11:29 AM
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So what is max boost? Anyone know?
10-13-2017, 11:40 AM
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Drifting
Hey Don, I seem to remember a thread somewhere here in Rennlist last year or so where boost levels for 958 CTTs was being discussed, I just can't seem to locate it.
In that thread I recall posting that on my 2011 CTT the max I've seen on the display is 13psi which corresponds to .89 bar. I seem to recall reading somewhere that Porsche lists max boost for this motor at .8 bar, so that's about right.
I'll see the 13psi only for a brief 'spike' I guess you'd call it, for just a short burst during full throttle acceleration, and then it settles out at a more steady 9psi or so in most instances IIRC. Again, this is during the rare instances I'm going full throttle on the thing.
Other times under normal or spirited driving (not full throttle) I'll see anywhere from 1psi up to 5-6 or so.
But again, max I've seen on my vehicle has been 13psi if that's what you're mainly after.
Does this help?
In that thread I recall posting that on my 2011 CTT the max I've seen on the display is 13psi which corresponds to .89 bar. I seem to recall reading somewhere that Porsche lists max boost for this motor at .8 bar, so that's about right.
I'll see the 13psi only for a brief 'spike' I guess you'd call it, for just a short burst during full throttle acceleration, and then it settles out at a more steady 9psi or so in most instances IIRC. Again, this is during the rare instances I'm going full throttle on the thing.
Other times under normal or spirited driving (not full throttle) I'll see anywhere from 1psi up to 5-6 or so.
But again, max I've seen on my vehicle has been 13psi if that's what you're mainly after.
Does this help?
10-13-2017, 11:46 AM
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From an older thread here on the 955/957 turbos https://rennlist.com/forums/porsche-...-turbo-s.html:
And then conflicting info from renntech: https://www.renntech.org/forums/topi...-stock-boost/:
Since 1-bar = ~ 15PSI (14.7 something..) the numbers in the two threads aren't even close. 0.6 Bar = 8.8 PSI.
Still puzzled..
Originally Posted by touarag
From Porsche for 2006, I dont see 2009 specs:
To provide such performance, Porsche engineers revised the engine control system’s throttle map, and installed larger intercoolers that improve volumetric efficiency by lowering the temperature of the air entering the V-8 engine’s intake tract. Thanks to the increase in the system’s cooling efficiency, engineers increased turbo boost pressure by 4.3 psi (0.3 bar) to a maximum of 27.5 psi (1.9 bar).
http://press.porsche.com/news/release.php?id=295
To provide such performance, Porsche engineers revised the engine control system’s throttle map, and installed larger intercoolers that improve volumetric efficiency by lowering the temperature of the air entering the V-8 engine’s intake tract. Thanks to the increase in the system’s cooling efficiency, engineers increased turbo boost pressure by 4.3 psi (0.3 bar) to a maximum of 27.5 psi (1.9 bar).
http://press.porsche.com/news/release.php?id=295
Originally Posted by renntech thread
Stock boost pressure for the 450HP Cayenne Turbo should be max 0,6 bar which reduces slightly to about 0,5 bar at higher rpm.
The 500 HP E81 Powerkit should have max 0,8 bar reducing to 0,65-0,7 at higher rpm. (Not verified, but a reasonable assumption based on different sources, feel free to correct this one).
The 521HP Turbo S should have max 0,9 bar reducing to 0,75-0,8 at higher rpm. (Not verified, but a reasonable assumption based on different sources, feel free to correct this one).
These are the standards; there are several other factors that may contribute to the actual boost pressure, such as atmospheric conditions, fuel quality and such detected by the engine management system.
The in-dash boostgauge is not known to be very precise so it might be a bit off.
The 500 HP E81 Powerkit should have max 0,8 bar reducing to 0,65-0,7 at higher rpm. (Not verified, but a reasonable assumption based on different sources, feel free to correct this one).
The 521HP Turbo S should have max 0,9 bar reducing to 0,75-0,8 at higher rpm. (Not verified, but a reasonable assumption based on different sources, feel free to correct this one).
These are the standards; there are several other factors that may contribute to the actual boost pressure, such as atmospheric conditions, fuel quality and such detected by the engine management system.
The in-dash boostgauge is not known to be very precise so it might be a bit off.
Still puzzled..
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10-13-2017, 11:50 AM
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In that thread I recall posting that on my 2011 CTT the max I've seen on the display is 13psi which corresponds to .89 bar. I seem to recall reading somewhere that Porsche lists max boost for this motor at .8 bar, so that's about right.
I'll see the 13psi only for a brief 'spike' I guess you'd call it, for just a short burst during full throttle acceleration, and then it settles out at a more steady 9psi or so in most instances IIRC. Again, this is during the rare instances I'm going full throttle on the thing.
Other times under normal or spirited driving (not full throttle) I'll see anywhere from 1psi up to 5-6 or so.
But again, max I've seen on my vehicle has been 13psi if that's what you're mainly after.
Does this help?
I'll see the 13psi only for a brief 'spike' I guess you'd call it, for just a short burst during full throttle acceleration, and then it settles out at a more steady 9psi or so in most instances IIRC. Again, this is during the rare instances I'm going full throttle on the thing.
Other times under normal or spirited driving (not full throttle) I'll see anywhere from 1psi up to 5-6 or so.
But again, max I've seen on my vehicle has been 13psi if that's what you're mainly after.
Does this help?
10-14-2017, 09:33 PM
#9
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After reading this thread I had to go out and give it a go. 958TT with 34k miles and stock but for Fabspeed pipes. Two runs up hill at full throttle yielded spike of 13 pounds with a steady 8-9 pounds until I ran out of hill and road.
10-14-2017, 11:41 PM
#10
Drifting
From an older thread here on the 955/957 turbos https://rennlist.com/forums/porsche-...-turbo-s.html:
And then conflicting info from renntech: https://www.renntech.org/forums/topi...-stock-boost/:
Since 1-bar = ~ 15PSI (14.7 something..) the numbers in the two threads aren't even close. 0.6 Bar = 8.8 PSI.
Still puzzled..
And then conflicting info from renntech: https://www.renntech.org/forums/topi...-stock-boost/:
Since 1-bar = ~ 15PSI (14.7 something..) the numbers in the two threads aren't even close. 0.6 Bar = 8.8 PSI.
Still puzzled..
1 bar = 14.5 psi so 0.7 bar boost on the gauge = 10.15 psig or 24.65 psi absolute.
10-15-2017, 12:47 PM
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And Termite01 - thanks for the numbers. I have to go find a hill (rare in my part of NJ which is basically at sea level.. and rather flat.)
10-15-2017, 02:23 PM
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I also have 2011 turbo, and I floor it regularly (some roads with 0 to 65-70 mph acceleration areas) and I'm seeing 8-9psi max in regular mode and 13psi in sport mode in low gears. At high speeds it's impossible to get the top boost without shifting manually because in auto mode the car downshifts to lower gear, ending up in rev zone where top boost is lower.
10-16-2017, 05:57 PM
#13
2014 CTTS.
Max boost I've seen has been up to about 12 psi, and then only briefly. TBH, I don't play around with it that often to max out boost.
What I've noticed is that if I'm in sport mode or shift manually and get above about 4K rpm, if I (or the tranny) do an upshift, I can hear a "thump" which I've always assumed is the diverter/wastegate opening to relieve the added boost. I say assume because it does seem to correlate with a drop in boost pressure.
Max boost I've seen has been up to about 12 psi, and then only briefly. TBH, I don't play around with it that often to max out boost.
What I've noticed is that if I'm in sport mode or shift manually and get above about 4K rpm, if I (or the tranny) do an upshift, I can hear a "thump" which I've always assumed is the diverter/wastegate opening to relieve the added boost. I say assume because it does seem to correlate with a drop in boost pressure.
