997 Turbo boost figures
Thread Starter
Racer
Joined: May 2006
Posts: 362
Likes: 0
From: London, UK
997 Turbo boost figures
Hi guys
I believe the 997 Turbo is supposed to get to 1.2 bar boost pressure with Sport Mode and overboost (1.0bar in Normal Mode). The Drivers Guide does show a pic of 1.2 bar with overboost arrow.
Anyway, recently I found a quiet stip of straight dry road, and had a play with the boost figures. I only ever use 99 octane Shell vPower fuel.
Normal Mode
If I put the car in 6th gear, then I can get 0.9 bar for about 1 sec, then it drops to 0.8 bar and stays there.
Sport Mode
Again, in 6th gear, I can get to 1.1 bar for a split-sec with the overboost arrow showing, then it drops to a constant 1.0 bar.
I am wondering if the reasons a lot of the guys with manual cars that are seeing 1.2 bar is because they have reduced the exhaust back-pressure from switching to an aftermarket exhaust?!
Either that or newer Turbos are being tuned-down slightly compared to early factory productions?!
What do you think? I would interested to know what other 997 Turbo owners have seen.
I believe the 997 Turbo is supposed to get to 1.2 bar boost pressure with Sport Mode and overboost (1.0bar in Normal Mode). The Drivers Guide does show a pic of 1.2 bar with overboost arrow.
Anyway, recently I found a quiet stip of straight dry road, and had a play with the boost figures. I only ever use 99 octane Shell vPower fuel.
Normal Mode
If I put the car in 6th gear, then I can get 0.9 bar for about 1 sec, then it drops to 0.8 bar and stays there.
Sport Mode
Again, in 6th gear, I can get to 1.1 bar for a split-sec with the overboost arrow showing, then it drops to a constant 1.0 bar.
I am wondering if the reasons a lot of the guys with manual cars that are seeing 1.2 bar is because they have reduced the exhaust back-pressure from switching to an aftermarket exhaust?!
Either that or newer Turbos are being tuned-down slightly compared to early factory productions?!
What do you think? I would interested to know what other 997 Turbo owners have seen.
Thread Starter
Racer
Joined: May 2006
Posts: 362
Likes: 0
From: London, UK
As I just replied to Jason on Rennteam:
Hmmm
How long do you see 1.2 for? As long as you have your foot fully down on the gas pedal?
And do you see this in 6th gear or are other gears easier to replicate with?
I am just wondering if Porsche have deliberately restricted MY08 Turbos for some reason?!
Hmmm
How long do you see 1.2 for? As long as you have your foot fully down on the gas pedal?
And do you see this in 6th gear or are other gears easier to replicate with?
I am just wondering if Porsche have deliberately restricted MY08 Turbos for some reason?!
Addict
Rennlist Member
Rennlist Member
Joined: May 2001
Posts: 4,463
Likes: 127
From: UK
The Motronic ECUs on these engines are looking at the mass of the air and comparing it to data in the program map the ECU will allow the boost to rise and fall to hit these target mass numbers. On a warm day the boost will tend to be higher since more air will be needed to hit the mass target.
When the weather is cooler like in the UK at the moment the ECU may ask for less boost to achieve the same target air mass hence you may only see 1.1bar now but 1.2 or even more in the summer.
The other thing which always has to be questioned is the accuracy of the boost gauge -I don't know how good the 997tt one is but typically 911tt boost gauges are pretty hit or miss on accuracy.
If you install a decent analogue boost gauge you will be able to watch how the ECU alters the boost constantly according to all the inputs it receives (if you are sad like me that is
)
When the weather is cooler like in the UK at the moment the ECU may ask for less boost to achieve the same target air mass hence you may only see 1.1bar now but 1.2 or even more in the summer.
The other thing which always has to be questioned is the accuracy of the boost gauge -I don't know how good the 997tt one is but typically 911tt boost gauges are pretty hit or miss on accuracy.
If you install a decent analogue boost gauge you will be able to watch how the ECU alters the boost constantly according to all the inputs it receives (if you are sad like me that is
)
Last edited by TB993tt; Jan 18, 2008 at 03:31 PM.
Racer
Joined: Oct 2003
Posts: 440
Likes: 0
From: San Diego
Hi guys
I believe the 997 Turbo is supposed to get to 1.2 bar boost pressure with Sport Mode and overboost (1.0bar in Normal Mode). The Drivers Guide does show a pic of 1.2 bar with overboost arrow.
Anyway, recently I found a quiet stip of straight dry road, and had a play with the boost figures. I only ever use 99 octane Shell vPower fuel.
Normal Mode
If I put the car in 6th gear, then I can get 0.9 bar for about 1 sec, then it drops to 0.8 bar and stays there.
Sport Mode
Again, in 6th gear, I can get to 1.1 bar for a split-sec with the overboost arrow showing, then it drops to a constant 1.0 bar.
I am wondering if the reasons a lot of the guys with manual cars that are seeing 1.2 bar is because they have reduced the exhaust back-pressure from switching to an aftermarket exhaust?!
Either that or newer Turbos are being tuned-down slightly compared to early factory productions?!
What do you think? I would interested to know what other 997 Turbo owners have seen.
I believe the 997 Turbo is supposed to get to 1.2 bar boost pressure with Sport Mode and overboost (1.0bar in Normal Mode). The Drivers Guide does show a pic of 1.2 bar with overboost arrow.
Anyway, recently I found a quiet stip of straight dry road, and had a play with the boost figures. I only ever use 99 octane Shell vPower fuel.
Normal Mode
If I put the car in 6th gear, then I can get 0.9 bar for about 1 sec, then it drops to 0.8 bar and stays there.
Sport Mode
Again, in 6th gear, I can get to 1.1 bar for a split-sec with the overboost arrow showing, then it drops to a constant 1.0 bar.
I am wondering if the reasons a lot of the guys with manual cars that are seeing 1.2 bar is because they have reduced the exhaust back-pressure from switching to an aftermarket exhaust?!
Either that or newer Turbos are being tuned-down slightly compared to early factory productions?!
What do you think? I would interested to know what other 997 Turbo owners have seen.
when my car was stock, it boosted 0.9 bars in normal mode between 2500 rpm or so, until 4000rpm, regardless of gear and regardless of temperature and with crappy 91 california octane.
In sport mode it would boost 1.2 bars all the time between 2500 and 4000 rpm especially in taller gears but also in lower gears and regardless of outside temp and then back to 0.9 beyond 4000 rpm or so.
Adding the aftermarket exhaust improved throttle response but had no effect on boost in my case. adding the ecu tune has a similar effect but the difference is that a tuned car will boost 1.2 bars all the way to redline.
Hope that helped.
Trending Topics
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Porsche's Top 5 Most Questionable Naming Decisions
Verdad Gallardo
Pogea Racing's 964 Porsche 911 Reimagination Stands Out in a Crowded Field
Verdad Gallardo
6 Convertible Top MYTHS Most People Don't Understand!
Michael S. Palmer
2026 Porsche 911 Club Coupe is Spectacular, And Everything Wrong with the Porsche Market
Joe Kucinski
Talos Takes Your 991 Porsche 911 GT3 to the Next Level for a Cool $1.13 Million
Verdad Gallardo
9 Vehicles Porsche Helped Engineer that Aren't Porsches
Verdad Gallardo
9 Features and Characteristics That Only Porsche People Understand
Verdad Gallardo
I've Written 500 Rennlist Articles: Here's How Porsche Has Changed Along the Way
Joe Kucinski
10 Most Unnecessary Porsches Ever Built (And Why We Love Them)
Verdad Gallardo
Thread Starter
Racer
Joined: May 2006
Posts: 362
Likes: 0
From: London, UK
Perhaps though it will get better after the car is more run in. This is more wishful thinking than anything else though .
What we need is someone with a MY08 Turbo to say whether thay can get 1.2 bar or not.
Instructor
Joined: Jan 2007
Posts: 124
Likes: 0
From: Miami,Florida
I am thinking the factory are now setting boost to 0.8 bar for Normal mode and 1.0 bar for Sport Mode for all MY08 cars. I doubt MY08 cars will be slower than older models so maybe Porsche have made small improvements in other areas and then dialed down the Turbos to balance it out?!
Perhaps though it will get better after the car is more run in. This is more wishful thinking than anything else though .
What we need is someone with a MY08 Turbo to say whether thay can get 1.2 bar or not.
Perhaps though it will get better after the car is more run in. This is more wishful thinking than anything else though .
What we need is someone with a MY08 Turbo to say whether thay can get 1.2 bar or not.
Addict
Rennlist Member
Rennlist Member
Joined: May 2001
Posts: 4,463
Likes: 127
From: UK
I am thinking the factory are now setting boost to 0.8 bar for Normal mode and 1.0 bar for Sport Mode for all MY08 cars. I doubt MY08 cars will be slower than older models so maybe Porsche have made small improvements in other areas and then dialed down the Turbos to balance it out?!
Perhaps though it will get better after the car is more run in. This is more wishful thinking than anything else though .
What we need is someone with a MY08 Turbo to say whether thay can get 1.2 bar or not.
Perhaps though it will get better after the car is more run in. This is more wishful thinking than anything else though .
What we need is someone with a MY08 Turbo to say whether thay can get 1.2 bar or not.
) the ECU is reading the air mass in kg/hr and adjusting boost to suit, the factory are NOT "setting" any levels of boost, it doesn't work like that - unless as you (paranoidly...sp ) imply they may be depriving you of your full 480PS DIN..... Boost on Motronically controlled Porsches is not neccessarily proportional to hp (when comparing one set of running conditions to another). There are Rlers running 1.2bar (on 993tts -older but same principal ECU) at peak power, managing about 470hp and others running high 500 hp at less than 1bar.....
If you are concerned that Porsche may be giving you less hp, get a GPS device and do some acceleration runs, missing hp is easily spotted, as you say it is possible (but unlikely) they can still make the 480PS power curve with less boost at DIN
Thread Starter
Racer
Joined: May 2006
Posts: 362
Likes: 0
From: London, UK
Did a bit more playing today. Managed to spot the ellusive 1.2 bar at last - albeit only for 1 second or so.
Strange it doesn't stay for longer even if I kept the gas pedal flat on the floor.
Strange it doesn't stay for longer even if I kept the gas pedal flat on the floor.
Racer
Joined: Jan 2014
Posts: 415
Likes: 0
From: Southeast
Thread revival...see i actually searched. Haha
Anyway i did rss engine mounts last night. My first diy on the car
I taking all the intake stuff off made me a little nervous but i think i got it all back on there. The only connection that is "suspect" is the passenger side black accordion joint by the maf sensor post air filter pre turbo but it is secure.
Anyway have gone for some drives to make sure i didnt have any boost leaks. My car seems to be trailing boost off more than before but not by much. Maybe 1-2 psi. So if i over boost starting at 2k in sport mode 5/6 gear it hits 17 for a second (like 3k rpm) then down to 14. In 1-4 gear im not seeing over 14 and it trails off to 10 psi in 1-2 and 12 psi in 3-4 gear.
This summer it was usually 80-100 degs and last couple days its been 60-70 so the lower boost may be because of that. Generally car feels ok.
I just never noticed such low boost in 1-4 gears and it seemed like it held 16-17 psi until at least 4k rpm before and now only 2800-3k.
Thoughts?
What boost do you all usually see at redline in each gear on a 70 deg nice day. I am stock ecu.
Anyway i did rss engine mounts last night. My first diy on the car
I taking all the intake stuff off made me a little nervous but i think i got it all back on there. The only connection that is "suspect" is the passenger side black accordion joint by the maf sensor post air filter pre turbo but it is secure.
Anyway have gone for some drives to make sure i didnt have any boost leaks. My car seems to be trailing boost off more than before but not by much. Maybe 1-2 psi. So if i over boost starting at 2k in sport mode 5/6 gear it hits 17 for a second (like 3k rpm) then down to 14. In 1-4 gear im not seeing over 14 and it trails off to 10 psi in 1-2 and 12 psi in 3-4 gear.
This summer it was usually 80-100 degs and last couple days its been 60-70 so the lower boost may be because of that. Generally car feels ok.
I just never noticed such low boost in 1-4 gears and it seemed like it held 16-17 psi until at least 4k rpm before and now only 2800-3k.
Thoughts?
What boost do you all usually see at redline in each gear on a 70 deg nice day. I am stock ecu.
