mopar bob

With the RE71r I have seen 1,3 G peak using Harry's and a Iphone 6s

sjfehr

I've seen as high as 1.7g using my phone with TrackAddict, but that's probably just the mount vibrating. I routinely see low 1.2x gees sustained on RE-71R in sweepers on our local grippy concrete, though. 1.35g instantaneous is plausible, especially if there was banking.

I have to run much higher pressures for autocross than track because of the higher transient loading.

Dan991C4

The Porsche tuner got back and said I need to be smother on the throttle and not go hammer down out of turns. The rapid change to full throttle opening is causing the timing to retard cutting a little power back defeating my purpose of accelerating out fast as possible while looking ahead and planning the next turns' attack. I have the normally aspirated Carrera 4's 3.4 L. and PDK in auto shift using the Cobb PDK aggressive shift tune. I'm going back to add the auto gear shifts data to the throttle position chart.

Dan991C4

Steering Input vs. G-Force over Three Runs
I checked some of my 911's SportChrono log data from another event to see how the G-Force data looks over time and if it is instantaneous/peaks. The graphs are three runs of data first with Speed vs. G-force and second Steering Angle vs. G-force. The peaks G-force was 1.25 G's on one run with the other two runs close. I need to make the steering inputs more consistent as data shows a lot of corrections. This data was also taken on the standard sway bars and I was fighting understeer more. I need to figure out how to combine the SportChrono log data with the Cobb Accessport data.



Speed vs. G-Force over Three Runs

burglar

Looks like you gained a ton of confidence by your third run on whatever element that was about 1/3 of the way through the course, going from 65kph to 70kph. What happened at the midway point in the course?

The three runs should look virtually identical. The 1st and 3rd look close, with the 3rd having generally higher speeds, the 2nd one looks almost like a different course.

Seems a little weird to me. I'm all for "squeezing" inputs rather than hammering them, but again I wouldn't worry so much about the small, momentary corrections to timing. Can you actually feel and/or hear the car bog down when you whack it to WOT?

edfishjr

To determine the amount of steering corrections I've found that you really have to isolate each longish corner and look at the lateral G variations (or steering inputs) blown up big. Sometimes you can see clear differences between runs, especially comparing runs from two different drivers. We always have to remember, however, that we should be testing the limits continuously, as the grip is constantly changing. So, a rock steady steering wheel within even a constant radius corner indicates under-driving. Same for the throttle position.

Dan991C4

The first run I was learning the course, The second run I was pushing trying to warm the tires up. The third run I was after a faster smooth time. I run the 20" GT3 track tires on my standard Carrera 4 so they need warmed up. The AWD system limits tire choices with the C4. I was monitoring the timing and fuel trim to see what the aftermarket ECD recalibration was doing and plus learning. I am loosing a little potential power with the timing corrections, but it is for safety and speed plots show a steady increase until I ease off the throttle. I switched from a Lotus Exige to the used Porsche C4 for daily drivability that's maybe not the best AX car. With the prices of the used GT4 dropping, I may upgrade in the future.