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>Hey Vigge, glad to see you're still at it!
I'am always at it since it interest me how my car is doing when more mods are piled to it.
A few questions regarding the graph that you posted above:
>1. Why bother to graph acceleration vs. rpm when acceleration already is >a=(Vf-Vi)/t and you aren't using equal rpm startpoints? I'm having a hard >time in seeing the value of that representation instead of just plain old >acceleration where someone can easily compare the various rates by their >respective slopes? What does the same data look like when graphed d/s vs. >time?
why bother with acc vs. rpm? Its a lot easier to make do analysis from the acc curve since it has a "direct" correlation to bhp and therefore you can basically see how the toque curve looks like. Keeping in simple if acc curve stays horizontal torque curve is horizontal aso. Of course wind resitance comes into play, but it does not affect the analysis too much when done base on runs which do not exceed 150km/h. Loss at the high end is roughly 35whp at 150km/h... Of course I take these figures into account if I calculate bhp based on acc.
Data which is used as the basis for the above graph
GT30 "un-adapted"
km/h time 10km/h time acceleration
60 0 0 0
70 1.84 1.84 1.509661836
80 2.72 0.88 3.156565657
90 3.36 0.64 4.340277778
100 3.97 0.61 4.553734062
110 4.6 0.63 4.409171076
120 5.28 0.68 4.08496732
this run was terminated at 130 since the calcuated bhp did exceed the 300bhp 4000rpms and I did not want to toast my pistons which where std at that time
calculated bhp and torque
http://viggen93.mine.nu/viggen/gt30_bhp.gif
GT28RS
km/h time 10km/h time acceleration
70 0 0 0
80 0.8 0.8 3.472222222
90 1.46 0.66 4.208754209
100 2.2 0.74 3.753753754
110 2.93 0.73 3.805175038
120 3.7 0.77 3.607503608
130 4.46 0.76 3.65497076
140 5.33 0.87 3.19284802
150 6.26 0.93 2.986857826
GT30 adapted
km/h time 10km/h time acceleration
90 0 0 0
100 0.83 0.83 3.346720214
110 1.64 0.81 3.429355281
120 2.5 0.86 3.22997416
130 3.44 0.94 2.955082742
140 4.5 1.06 2.620545073
150 5.76 1.26 2.204585538
please take copy&paste these values to excel and to the plots you want
>2. What was happening during the periods when the acceleration is zero >for all 3 data sets? If the data was logged from 70 to 150 kph for all >plots wouldn't the acceleration curves all start at the same respective >rpm's?
the date is not logged for 70-150 for all the run, see figures above which the intervals have been for each run. Also the plot has a error in it, the timing is from flying start so the acceleration is never 0.
The correct graph does look like this
http://viggen93.mine.nu/viggen/saabnet1.gif
>3. In order to meaningfully compare runs to one another wouldn't the >beginning ground speed (and thus rpm's) have to be equal? Do you have >enough data to show entire runs, all starting at X rpms with a mash to >WOT at T=0? I think that would provide a great picture into the overall >response.
nope the result is just about the same where ever you start the run, if you dont take "under spool-up" values into account. Mine are from flying start so it does not matter how you compare them. Of course if HW is so stressed that it can only supply 100% power through a short acceleration it will make a difference if you compare 2000-6500rpm or 4500-6000rpm acc values. How ever this is not the case with my car.
If responce is at interest then you shall start all the runs from the exact same rpm.
>4. To me, it looks like you've proved your point (provided all outside >conditions, full tank of gas, same passenger situations, etc. were all >the same). Would you be willing to show a graph of speed vs. time? Or >possibly convert the above RPM back to ground speed for acceleration vs. >velocity?
Finnish summer is pretty stable what comes into ambient temp, roughly +20deg C, so it hardly plays a role. Also intake temps during a 3rd gear run do not exceed +40deg C. I use the same road strip for all my measurements.
Load: 1person always, never with full nor empty tank. Even if there is a slight load change it will not fool too much. A 100kg load equates to 0.1s loss 80-120run based on 20 or so tries with my car.
>If I'm interpretating the data correctly it looks like both of the >adapted runs gave more fierce acceleration (larger rate of change per >rpm) over a more narrow amount of time but the new turbo, unadapted, >ultimately was able to accelerate the car faster but at a lower rate of >change. It's good to see that after adaption the slope of the >acceleration curve nearly matches that of the 28...the 30 likely needing >the higher flow rate from higher rpm operation to reach it's area of >operation efficiency but then experiencing flow limit decreases from T7. >For sure post some followup comparisons after you get the software to >keep that bad boy in it's efficient operating island. Are you sure that >your A/F was good with the 30 before adaption? Don't know why it would >cut timing...what did your manifold pressure look like during the above? >Did it allow for an overshoot?
boost and airmass, not completely adapted (note the overshoot compared to the GT28RS. The request curve is fairly close to the GT28RS curve)
http://viggen93.mine.nu/viggen/gt_31.gif
http://viggen93.mine.nu/viggen/gt_32.gif
A/F around 11. So if you have higher airmass, about the same A/F the only thing that can really cut the performance is timing ;)
>Some b
>Don't know what your data logging capabilities are but it would be great >to see a plot of acceleration vs. manifold pressure and acceleration vs. >flow over top of intake temps.
I can log evertying from OBD-port (mostly use it for timing, intake temps, airmass, boost) + W-band O2, EGT. G-tech Pro and speedometer for performance figures
intake temps
A normal 3rd gear run when IC is cool results to
http://viggen93.mine.nu/viggen/temp_301.gif
here is a run from yesterday 0-250km/h. This was 4th run of that kind in a fairly short period of time and the IC was very hot to begin with. Ambient +25deg C
http://viggen93.mine.nu/viggen/sp_temp1.gif
SW should now be correct (as far as I got to test it) but my wastegate clock is now toasted and I need to replace it before I can do any more "real" testing. More will follow...
posted by 81.197.250...
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