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Jan 13, 2009 12:05:50 PM
- Alex_997TT
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- Loc: Reading , United Kingdom
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- Reply to: 911terror
Re: 997 GT2 tunning question
Well TB993tt has been researching this very question for his 997GT2:
http://www.rennteam.com/forum/thread/20070269/Incoming_GT2/page1.html
I think he's leaning towards RS-Tuning (Cargraphic)
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Jan 13, 2009 12:12:19 PM
- andrea
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- Loc: Italy, Pordenone , Italy
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- Reply to: Alex_997TT
Jan 13, 2009 12:19:42 PM
- Alex_997TT
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- Loc: Reading , United Kingdom
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- Reply to: andrea
Re: 997 GT2 tunning question
EUNICE - bug!!
Try page 2 link: http://www.rennteam.com/forum/thread/20070307/Re_Incoming_GT2/page2.html#20070307
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Re: 997 GT2 tunning question
Have put all this stuff on Rennlist but here it is for those who don't visit there....
I fitted Cargraphic/RS Tuning headers and cats to the GT2, dyno chart is below.....
This is a fantastic modification, sounds like stock at idel and cruise but glorious when on boost exciting and quite exotic sounding...... The weather is cold at the moment in the UK ~0degC and when I stab the throttle at 3000rpm in 3rd gear upwards, the torque will overwhelm the stock clutch !!!
I reckon in these temperatures the engine is kicking out ~740NM in order to slip the clutch and it must be the suddeness of the torque delivery which makes it slip since 997tts with the smaller VTGs seem able to cope with mid to high 700NM without such slippage....
The first graph below is standard 500 miles ZERO mods 0 DegC 60-130 in 8.3s
The graph below is same track 10 degC cats and headers 1600 miles RS engine dyno proven at 560PS/700NM....... 60-130 in 7.8s
Feb 3, 2009 4:40:05 PM
- Alex_997TT
- Rennteam Master
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- Loc: Reading , United Kingdom
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- Reply to: TB993tt
Feb 3, 2009 6:19:22 PM
- TB993tt
- Rennteam Pro
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- Loc: manchester , United Kingdom
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- Reply to: Alex_997TT
Re: 997 GT2 tunning question
Hi Alex, this car has loads of traction as long as its dry,....
The car feels really sweet how it is, I guess when the weather gets warmer it may start to lose its edge as the IATs heat up so may need the ECU tune although I am reluctant to void the warranty when it it feels plenty fast - a 600rpm higher limiter would be nice however...
What do you make of the slipping clutch ? is yours doing it ? try 4th gear, hold at 3000rpm then boot the throttle WOT aggressively, big growl and clutch slip is what I am seeing even with 700NM (prob more like 740NM in this temp).... If yours isn't slipping then why not ? is it the bigger VTGs giving a harder initial hit ?
Feb 3, 2009 6:54:51 PM
- Alex_997TT
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- Loc: Reading , United Kingdom
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- Reply to: TB993tt
Re: 997 GT2 tunning question
Don't know about the clutch slip Toby.
I must admit that in the winter I never put the car into even Sport mode for full over-boost torque, there is just no need as she's plenty fast enough in normal mode (under 1.0 bar boost).
My car is feeling a bit twitchy currently under high acceleration anyway (even in a straight line on a-roads) so I have booked back in to see Chris at Center Gravity. We are going to play with the geo and sway settings some more.
I have seen 1.2 bar plenty last summer though on the motorways and no clutch slip at all.
What max boost does your GT2 produce on the gauge?
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Feb 4, 2009 7:36:07 AM
- intouch1
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- Loc: Red Sea , Egypt
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- Reply to: Alex_997TT
Re: 997 GT2 tunning question
Alex, in current weather boost is about 1.2bar max, the way the GT2 engine is mapped the boost ramps up to ~1bar for peak torque then stays there til ~5000rpm then it goes up again to 1.2-1.4bar (according to ambient conditions) and the expansion manifold does its thing with the boost staying at this level to the limiter.
intouch.... trust me I guarantee you you would not look back from this mod, it does not change the factory programming so the character of the torque delivery is the same, the extra torque is pure efficiency......
Re: 997 GT2 tunning question
funny you talk about boost. just yesterday i took my gt2 for a run as the kid of one of my managers was dreaming about a ride in a porsche. he's 10 years old and i picked him up from school.....about a 40 km drive to his parents house.....never have i seen a 10 year old so quite :)
on the way there i played around with the car to see when what boost is on tap. ambient temperature is about 27 C at the moment.
boost is mainyl stuck around 1.0-1.1 bar. only in the hugher rev range from about 5000 rpm did it go all the way to 1.4......
the boost of my turbo tip is very different. it always maxes at 1.1-1.2 when nailing kickdown.
gt2 is mighty faster 
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Speed has never killed anyone, suddenly becoming stationary... That's what gets you.
Re: 997 GT2 tunning question
MKSGR:
Has physics changed since I went to school?
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fritz
There have been some major changes in nature recently
That's correct, they have released Version 0.9 (beta for public preview) - less power consumption while maintaining a higher overall temperature.
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Matt C
2005 997 C2S / 1988 911 3.2 Conv.
Re: 997 GT2 tunning question
Matt C:I guess that'll be to make provision for global warming?
MKSGR:
Has physics changed since I went to school?
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fritz
There have been some major changes in nature recently
That's correct, they have released Version 0.9 (beta for public preview) - less power consumption while maintaining a higher overall temperature.
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Matt C
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fritz
Re: 997 GT2 tunning question
TB993tt:
I told Cargraphic that their graph was wrong and they revised it - see below, but it is still wrong !
Yes, it is still wrong. 
Since their torque / power plots are obviously not computer-generated maybe they should give the job of correcting them to an apprentice, who should at least recognize at first sight that something is wrong with them. On the other hand, he may already be fully occupied doing their dyno development work for them. 
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fritz
Re: 997 GT2 tunning question
Fritz
They are supposedly copied directly from RS Tuning engine dyno diagrams but like you say they are badly copied !
I did ask for an original diagram but nothing was forthcoming.....
I can however confirm that the quoted increased numbers are very realistic based on the road performance with these parts...
Re: 997 GT2 tunning question
TB993tt:
Fritz
They are supposedly copied directly from RS Tuning engine dyno diagrams but like you say they are badly copied !
It's not just a question of bad copying. Engine dynos actually measure torque through the rev range, and the corresponding power figures are then calculated from the torque at each engine speed according to the formula:
P = 2 x pi x M x n
or simplified to:
P = M x n / 9549
where
P = Power in kW, M = Torque in Nm, and n = engine speed in rpm.
The relationships for the respective power and torque curves for each engine shown above do not correspond to each other, even allowing for multiplication of torque figures by engine speed, and it is more than just a question of the dots being badly joined up.
Two engines whose torque curves crossed at a certain rpm, as shown in the first example, would by definition also have the same power output at that engine speed.
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fritz
Re: 997 GT2 tunning question
fritz:
TB993tt:
Fritz
It's not just a question of bad copying. Engine dynos actually measure torque through the rev range, and the corresponding power figures are then calculated from the torque at each engine speed according to the formula:
P = 2 x pi x M x n
or simplified to:
P = M x n / 9549
where
P = Power in kW, M = Torque in Nm, and n = engine speed in rpm.
The relationships for the respective power and torque curves for each engine shown above do not correspond to each other, even allowing for multiplication of torque figures by engine speed, and it is more than just a question of the dots being badly joined up.
Two engines whose torque curves crossed at a certain rpm, as shown in the first example, would by definition also have the same power output at that engine speed.
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fritz
Or for hp sae: hp sae = torque lb/ft * rpm/5252
I think you will find it is just bad copying
Re: 997 GT2 tuning question
TB993tt:
fritz:
TB993tt:
Fritz
It's not just a question of bad copying. Engine dynos actually measure torque through the rev range, and the corresponding power figures are then calculated from the torque at each engine speed according to the formula:
P = 2 x pi x M x n
or simplified to:
P = M x n / 9549
where
P = Power in kW, M = Torque in Nm, and n = engine speed in rpm.
The relationships for the respective power and torque curves for each engine shown above do not correspond to each other, even allowing for multiplication of torque figures by engine speed, and it is more than just a question of the dots being badly joined up.
Two engines whose torque curves crossed at a certain rpm, as shown in the first example, would by definition also have the same power output at that engine speed.
--
fritz
Or for hp sae: hp sae = torque lb/ft * rpm/5252
I think you will find it is just bad copying
The amateur pedant in me says that "bad copying" does not explain how the torque values of both engines have fallen to an identical level of around 260 Nm at 6750 rpm, but the power curves have continued to diverge to a difference in value of about 30 hp at the same rpm. A physical impossibility. 
It does say that whoever "corrected" the graphs before sending them to you must have been a dilettante not to have noticed this discrepancy. 
To take pedantry to its conclusion, the British unit for torque was in fact "lb ft" (pounds feet), not "lb/ft" (pounds per foot), or - to follow British engineering convention absolutely correctly - the unit of torque should in fact be "lbf ft", where "lbf" is the abbreviation for "pounds force" to differentiate it from "pounds mass". A pound force and a pound mass are only identical when gravitational "force" happens to be 1g. That is, at the earth's surface.
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fritz
Re: 997 GT2 tuning question
fritzYou mean 600NM at 6750rpm, which is about 577PS - so according to the graph even the stock motor has 577PSthe amateur pedant in me says that "bad copying" does not explain how the torque values of both engines have fallen to an identical level of around 260 Nm at 6750 rpm, but the power curves have continued to diverge to a difference in value of about 30 hp at the same rpm. A physical impossibility.
It does say that whoever "corrected" the graphs before sending them to you must have been a dilettante not to have noticed this discrepancy.
To take pedantry to its conclusion, the British unit for torque was in fact "lb ft" (pounds feet), not "lb/ft" (pounds per foot), or - to follow British engineering convention absolutely correctly - the unit of torque should in fact be "lbf ft", where "lbf" is the abbreviation for "pounds force" to differentiate it from "pounds mass". A pound force and a pound mass are only identical when gravitational "force" happens to be 1g. That is, at the earth's surface.
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fritz
I am guessing that they copy the graphs since the original data will come to them in that "join the dot" format from RS Tuning's software - someone has just innacurately and sloppily transfered the data, very poor imo and as you say to allow the torque values to become the same (actually worse for the tuned engine in the first uncorrected diagram!) at peak power shows a complete lack of understanding which is somewhat disturbing for a company selling this sort of high end stuff ! My guess is it was left to some "creative" to do ?
Thanks for the lesson in "lbf ft" - didn't know that 
Re: 997 GT2 tuning question
TB993tt:
fritzYou mean 600NM at 6750rpm, which is about 577PS - so according to the graph even the stock motor has 577PSthe amateur pedant in me says that "bad copying" does not explain how the torque values of both engines have fallen to an identical level of around 260 Nm at 6750 rpm, but the power curves have continued to diverge to a difference in value of about 30 hp at the same rpm. A physical impossibility.
It does say that whoever "corrected" the graphs before sending them to you must have been a dilettante not to have noticed this discrepancy.
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fritzI am guessing that they copy the graphs since the original data will come to them in that "join the dot" format from RS Tuning's software - someone has just innacurately and sloppily transfered the data, very poor imo and as you say to allow the torque values to become the same (actually worse for the tuned engine in the first uncorrected diagram!) at peak power shows a complete lack of understanding which is somewhat disturbing for a company selling this sort of high end stuff ! My guess is it was left to some "creative" to do ?
1) Re: "You mean 600NM at 6750rpm, which is about 577PS - so according to the graph even the stock motor has 577PS"
You are right about the torque figure for both engines being shown as about 600 Nm at 6750 rpm, of course. That's what I get for calling someone else a dilettante!
600Nm at 6750rpm works out to be 424 kW or 577 metric hp/PS, which obviously cannot be right for the stock engine. The manufacturer's graph indicates figures around 550 Nm and 390 kW / 530 PS. Someone appears to have used the wrong figures for the graph for the stock engine.
2) Re: "... someone has just innacurately and sloppily transfered the data, very poor imo and as you say to allow the torque values to become the same (actually worse for the tuned engine in the first uncorrected diagram!) at peak power shows a complete lack of understanding which is somewhat disturbing for a company selling this sort of high end stuff ! "
That's exactly what I thought, and is why I have labored this point somewhat in this thread.
2) Re: "My guess is it was left to some "creative" to do ?
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fritz
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