GIAC "stock mode" may be equivalent but not identical to Porsche stock. Also depends on your hardware, i.e. exhaust.

 

Mine is a late 06 build date, and it has the 0-9-18 boost graph and in the higher gears it hits 18 on the graph with the ^ arrow next to it. Thanks for the info, this is a helpful thread.

 

Both excellent points Dave. Per GIAC, the GIAC's stock mode has identical maps for AFR, boost, and timing, etc., to stock ECU.
I actually still have 2 ECU's, the original one that came with the car and a second one that was flashed using car's VIN and then loaded with GIAC program. I've switched and compared them in the past and they did seem to behave indentically subjectively (unfortunately no Durametric then).

And thanks for the reminder about the exhaust - very good point that I forgot about! I should be more clear that the Durametric boost I've been posting is with the Cargraphic exhaust.

One question pls: assume files are identical, could a more free flow exhaust alone cause an increase in boost pressure?
In other words, how does an after-market exhaust increase power, assume that it does:
a. Increased power at same peak boost?
b. Increased boost and therefore more power?
TIA

 

If the exhaust is restrictive then even if the program calls for x amount of boost the hardware may not allow it to get there. A restrictive exhaust will also affect VE, the overall pumping efficiency of the motor (i.e. backpressure) such that max flow and power would be limited.

 

On a stock ECU the engine should always give you same power no matter what temperature etc you see since its a load based system, or am I wrong?

If it is cold the engine will lower boost to still "only" give you 480hp and I assume it will "try" to do something similar if you remove the restrictions after the turbos.

 

No -- environmental conditions, i.e. temperature, altitude will have an affect on max power. That's why in the fall when air temps are cooler you start to see an uptick in people posting their 60-130 times.

 

Got it, thanks Dave.

Question: The max amount of boost, say at ideal perfect condition, is set/controlled by the ECU programmer right?

In other words, tuner would set max boost in the car, say at 22 psi, then depending on the conditions, you could see boost anywhere below 22 psi, but never above?

 

That's basically correct, tuner can adjust to whatever, i.e. normal vs sport mode.

 

Hi tomb18, I'm also from Montreal and bought my Canadian '07 TT in Toronto. I really think that OEM boost gauge is not always super accurate, some days I was able to hit 17 PSI and other days the car could barely it 13-14 PSI. The weather is a factor but I'm almost sure that the boost gauge is the problem.

Have you tried EK Performance on Jean-Talon? They have been in the business for 30 years and they really know Porsches. I always go there and avoid going to the dealer as much as possible.

 

Hi Carlito,

My car is still under CPO, but I will look elsewhere in the future. Also heard of someone in ndg.

You have a Europipe? Love to hear that. Want to get one.

 

Hi there, assuming I understand your questions, Dave's explanation, and this issue correctly :-):

1. No, I don't believe so. For example let's look at the dyno simulation that we are doing, 2000 rpm cruising at higher gear (large load on the engine) then WOT: I don't think the request is for a specific fixed torque number, but for a *MAX* torque. In response to this max torque request, the boost will go to max allowable value set by the tuner, say 18 psi. How much power you will get then depend on operating conditions that Dave mentioned.
When I was at GIAC, what I remember is that the engineers would look at AFR, boost, timing curves, etc., THEN modify the ECU's program, THEN run the dyno to see what power they would be getting. In other words, they have control over boost values, but DO NOT know or have control over what power the engine will produce as a result.

2. I think this is unlikely. At lower temp, boost should stay same not reduced, and power will be higher as Dave has mentioned. If ever there is a time that boost is limited, I would think it's in the opposite condition: super high temp.
In particular with an after-market exhaust, I think there's never been a report of boost being lower with a more free flowing exhaust. I am sure it would make quite a bit of news if that's the case! For sure that's not what's happening in my car with the Cargraphic exhaust.

Very interesting to see what Durametric will show in your car. In "reasonable" operating conditions, if that measures lower than 17 Sport, and engine load lower as a result, then I think there might be a problem. You might want to do your run same way as mine so the numbers are comparable: 2000 rpm, third gear, then WOT. With this, psi was 19.4, engine load 172. with CG exhaust.

 

On a tuned ecu the car might be targeting an absolut boost value, but I am not sure it will if it is stock. I will have to log in different temps to check though.

I used to have a bmw 335i and it would always give you a fixed torque no matter what you did (if running stock software) so in cold weather you got much lower boost BUT it had a much newer siemens ecu than the gt1 has so it might be different for us.

BTW I did a quick run today following your instructions and in sport mode at around 4k rpm I get over 1bar on the in-dash gauge

 

Well did get some logs yesterday, not super impressed with the Durametric setup, I would really like a hw dongle dedicated flight-recorder instead, not sure if that exists at all though...

Anyways, here's the graph of boost and load for a 4th gear SportMode pull:



So is this correct do I see 172 load at 1bar boost?

 

Sorry about the x-axis should be rpm from 2000-6500 on that axis, not all friendly with excel today.

I had around 20deg Celcius yesterday here and I am pretty much down at sea level, I had 1010mBar pressure yesterday so I took the absolute values from the log and subtracted 1000 to get those values in the graph.

It is interesting that I see exactly a max load value of 172 as cannga did even though my air pressure was different and temperature quite much lower. I also had the same load but at lower boost, I think this is due to the colder air is denser thus the car doesnt have to boost as much to reach its "Load Target".

If this is correct then this car seems to behave very much like my former BMW.

Any feedback on my thoughts and data is appreciated since i am very new to the 997!

 

I also saw 1.2Bar in dash today going WOT in 6th gear (it was much warmer and flooring it in 6th seems to make the turbo's spinn like crazy, no log from this though...I am not sure the in dash gauge is all that good for this since it is easy to get boost spikes when one get of the pedal and I cant look concentrated at the little bar chart growing.