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Discussion Starter · #1 ·
The ignition timing is very suspect at the moment, and I wish a had a wideband O2 sensor input, but eh. Whatcha gonna do?

The intercooler has been "ducted" so that air is forced over it, and the intake system has been heat isolated. I was also running a non heat isolated cone style air-filter. (Hence the ~80F static intake temps despite 56F ambient.)

The ambient temperature was 56F degrees, the humidity was 100%, and during the run listed it was sprinking water a little. (Definitely going to have to see what the temps are like on a hot-dry day.) But the fact that full throttle from a stop to around 80 mph only raised intake temps 40 degrees at this temperature was somewhat comforting ... only somewhat.

)

Vigge had asked me to get some more accurate air-mass/combustion values because the data was not synchronized. I used a set of RPM values where the MAP was nearly constant, and RPM rate of climb was nearly constant, and used a line regression which worked well.

The regression for this specific data set was RPM = 167.28T - 45.77

Validation to show that a line regression should be accurate even for data points not directly plotted.

Then I just plugged in the exact time for specific MAF values into the formula and got an exact RPM to base the calculations from.

The direct conversion from lbs/min to grams/second is about 7.56.

Milligrams/Combustion = (lbs/minute) x (453.6 grams/lb) x (1000 milligrams/gram) / [ (Revolutions/Minute) x (2 combustions/ Revolution)]

@ T = 17.293 s
MAF = 12.03 lbs/minute
RPM = 2847
Air-mass/combustion = 958 milligrams/combustion

@ T = 19.426 s
MAF = 14.84 lbs/minute
RPM = 3204
Air-mass/combustion = 1050 milligrams/combustion

@ T = 21.589 s
MAF = 16.27 lbs/minute
RPM = 3566
Air-mass/combustion = 1,035 milligrams/combustion

@ T = 23.682 s
MAF = 17.01 lbs/minute
RPM = 3916
Air-mass/combustion = 985 milligrams/combustion

That should give a pretty good idea. I found that the sampling rate on my logger is variable for each kind of data. So for things which do not change quickly I can lower the sampling rate, and things which do increase quickly, can change the sampling rate. (As low as 50ms) That should help things.

Dubbya~
 

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Discussion Starter · #2 ·
More data with a reset ECU ...

Here's a long-term reading from the MAF sensor. At at a few points it reads over 24 lbs/min of airflow. The ignition advance is only about 12.5 degrees at that point and the RPM is about 5,500. That's about 265 hp worth of airflow ...
Just needs a water-meth injection so the ECU will advance the timing a bit.

At 12.5 degrees total advance, it'd be probably making around 250 hp ... which is about perfectly in line with my dyno-test results.



Also, with some extensive heat-isolation mods, a cooler thermostat, and some cool weather, check out this intake temp vs manifold pressure graph ...

Manifold Absolute Pressure is in blue, and the units are inches of Mercury.

Intake temperature is in pink, and the units are degrees Fahrenheit.



Ambient Temp was 50F, and it was done at about 1,000 ft above sea level.

Dubbya~
 

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Discussion Starter · #3 ·
Also, here's a good graph showing how T7 uses the throttle to control boost pressure ...

Pink = throttle
Blue = manifold pressure in absolute inches of Hg



Dubbya~
 

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Originally posted by Adrian W:
[qb]Here are some interesting things to note from this:

1. At least on my car T7 appears to be controlling boost entirely by throttle angle. This would be why BOV's don't work well with T7, and why T7 has a solenoid to control the ByPassValve.  At full boost, the throttle was frequently only 50% open.  Even at nearly 5000 RPM it was only 74% open.


Dubbya~ [/qb][/b]
This controlling boost by throttle angle makes sense to me too, from some things I have seen on my Aero, which have not previously been explainable.
A)I have tried running the car with the wastegate control solenoid electrically unplugged, this ran OK but was totally SLOW. I was not getting anywhere near base boost, but only reaching about +0.1bar. The system was finding some 'other' way of regulating boost.

B)This could also explain why I can get best performance by finding the 'sweet spot' for the throttle pedal, which is NEVER full throttle and mostly a lot less than full. The technique is to give it full boot and then once up to full boost, back off as far as possible, whilst still maintaining full boost. This is not just my imagination, I have the rolling road results to prove it
Seems like what T7 is trying to do on your car?

How are you able to log this data?
 

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Originally posted by SJ:
[qb] QUOTE
Originally posted by Adrian W:
[qb] Here are some interesting things to note from this:

1. At least on my car T7 appears to be controlling boost entirely by throttle angle. This would be why BOV's don't work well with T7, and why T7 has a solenoid to control the ByPassValve.  At full boost, the throttle was frequently only 50% open.  Even at nearly 5000 RPM it was only 74% open.


Dubbya~ [/qb][/b]
This controlling boost by throttle angle makes sense to me too, from some things I have seen on my Aero, which have not previously been explainable.
[/qb][/b][/quote]WIS states about the following

Airmass that is going into the engine is primarely controlled by throttleplate. If the asked value cant be achieved by throttle plate control then turbo control will take over.
 

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Discussion Starter · #6 ·
I'm logging the data with the Auto Enginuity Scan Tool.

I think in most cases if you get more power by letting off the throttle, the throttle position sensor, or ECU, is probably faulty in some way or another.

I remember reading that quote in the WIS and thinking to myself "Well if the throttle is wide open, and you're still not getting the 'requested' vaues ... how is turbo control going to help? It can only open the wastegate and dump boost."

The WIS words it poorly. Anything above 5-6 psi of boost is hard to regulate by throttle alone because you get massive pressure before the throttle, and it overheats the turbo by sending so much exhaust gas through it instead of bypassing it through the wastegate.

So basically ~6 psi or more and the turbo and throttle work together, with the throttle "fine tuning" the boost that the turbo is putting out. In case of emergency, the throttle can be used alone.

Makes sense to me anyhow.

I can't believe it. I reset the ECU and gained 55 hp worth of airflow. Something is seriously getting screwy with the car. Gotta figure it out.

Dubbya~
 

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Adrian and others, i like your style, keep that test info coming, as im starting to lay down some foundations of how this T7 operates .

i also chekd out your discovered facts and intimations on the sacentral site mainly in the dialogue exchanges with Dr boost.

Im now much more inclined to be very vigilant in any choice of power upgrade in the future, with the VE improvement method still the favoured way but if only the price could be minimised.

It would also be beneficial if an updated process of power upgrade procedures or add-ons could be listed for the T7 based on your fact-finding data.

I assume you do these investigations in your spare time, so no expectations are put forth, but all great work reaps its own rewards
 

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B)This could also explain why I can get best performance by finding the 'sweet spot' for the throttle pedal, which is NEVER full throttle and mostly a lot less than full. The technique is to give it full boot and then once up to full boost, back off as far as possible, whilst still maintaining full boost. This is not just my imagination, I have the rolling road results to prove it Seems like what T7 is trying to do on your car?[/b]
Wow, this is exactly the same behavior that I recognise on my Viggen! At the moment I haven't found an explanation for it, but the effect is unmistakably there.
 

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Maybe there is something faulty with my throttle position sensor, but everything seems healthy enough...

1) no fault codes/CEL
2) dealers can find no problems
3) has been consistently like this for nearly 2 years.
4) excellent fuel economy
5) rolling road shows slightly above spec when driven full throttle
6) rolling road shows well above spec when using part throttle (247 on 230 spec car)

Hanm - it's nice to know I'm not the only one who experiences this. (get the right pedal position and the power is stunning )
 
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