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I dropped it to a 2:04:96 with a fair number of 2:05s and 2:06s through several sessions. I hit the 2:04 on lap 10. This was about the time my power loss problem started up again. This time I actually got an engine code of P0308 number 8 cylinder misfire. Car is at dealership and maybe the code will help identify what has been intermittently happening over the last year.
Here is the data from Cosworth Toolbox showing related temps, speeds and times.
Once I get the following session the video uploaded I will post it. It shows where the power loss was keeping me from passing a fast BMW. Even with the loss we were still turning 2:06 laps but I could feel the engine surging when wide open.
Adding the second video showing the light blue BMW I was following.
Working on another video showing side by side running on the track along with leap frog passing during an Instructor Track Exercise session. I had one of my students with me and it turned out to be a very fun session. Wish I could have had side and rear cameras during this session.
Bill
Last edited by Bill Dearborn; 10-03-2017 at 02:49 AM.
Good laps, lots of silver cars in the way. If you can do lap trace overlays, I think you will find some variance in speed approach and thru the climbing esses. Very consistent cornering lines when not influenced by traffic. I noticed the brake gauge never went above 40% which surprised me. Water, oil and tranny temps were good on this run.
Now that I'm out west, I won't get to drive a powerful car at VIR :<(
Thanks for sharing Bill
Whats was the ambient ?
I also noticed that you avoid 2nd gear. Is this to carry more momentum through the turns ? On a positive side it's helping temps.
Thanks for sharing Bill
Whats was the ambient ?
I also noticed that you avoid 2nd gear. Is this to carry more momentum through the turns ? On a positive side it's helping temps.
It was a fantastic weekend Fri through Sun temps were ideal. Mid 70s to low 80s and sunny.
I tried second a couple of times coming out of Oak Tree but like always find it doesn't really provide any benefit. It is just an extra down shift and up shift which increases the chance of screwing up. Don't use it and you don't get that chance for error.
Also if you can't go wide open through a corner in a higher gear you sure won't be able to do it in a lower gear so why bother downshifting? As you said the higher rpms increase heat without being able to put any more power to the pavement.
Being in a higher gear makes it easier to play with the throttle in the turn if you want to change your yaw angle to get a better line through the turn.
I have only found a couple of tracks where second gear is really useful. CMP in SC is one of them.
Good laps, lots of silver cars in the way. If you can do lap trace overlays, I think you will find some variance in speed approach and thru the climbing esses. Very consistent cornering lines when not influenced by traffic. I noticed the brake gauge never went above 40% which surprised me. Water, oil and tranny temps were good on this run.
Now that I'm out west, I won't get to drive a powerful car at VIR :<(
The brake gauge is percentage of pedal travel. If it ever goes to 100 it means your pedal is in the floor.
Bill, if you're interested in me doing some data analysis in Pi toolbox I think it would be interesting for everyone. I just need to get your MP4 file.
Bill, if you're interested in me doing some data analysis in Pi toolbox I think it would be interesting for everyone. I just need to get your MP4 file.
Sounds good. Will try to get it uploaded to a server some time today. Car is at dealership to deal with the power loss issue and P0308 code.
Getting some feedback from GM Engineering suggesting to bleed the intercooler again. They say the rear two cylinders run the hottest and if the intercooler isn't topped off properly that could cause the intake air for those two cylinders to be too hot and result in the misfire code.
If that is the issue it makes me wonder if the solution might be as simple as adding a small expansion tube to the top of reservoir and keeping the reservoir full to the top with all of the fluid expansion taken up in the tube above it. Then all they would have to do is redesign the reservoir, test it and release it as some sort of GMPP product that owners can add in place of the standard reservoir. Similar to the Secondary Radiator.
They are still trying to figure out why the issue is so intermittent. Can run for hours with no issues and then have issues for a few hours with problem disappearing after that.
Thanks for sharing. Can you post your car setup (tires, brakes, mods, etc.)? Apologies if everyone else here already knows...
Sure thing. Car has Shark Bar, Schroth ASM belts, running Pirelli P Zero Slicks 305/645/18 on CCW 18x11 Corsair wheel in front and 325/660/18 on OZ Racing 18x12 (C6Z track wheel with 59 mm offset). The 325 is a little small so the mph indicated in the videos is 2 or 3 mph high.
Alignment is -2.5 deg front camber with +7.4 caster, and slight toe in (toe in to try and reduce street tire inside wear), rear camber is -1.8 with +0.8 caster and toe close to zero (may be slightly in or out but my eyes can't resolve the small measurement).
Granatelli Toe links in place of stock toe links (do not have AMT plate that replaces the stock toe link cam).
Have Essex Parts Pro 5000 AP Racing Kit with 372 mm front rotors and 25 mm thick brake pads. Essex AP Racing rear brake kit. Running 1.11 pads front and rear.
Everything else is bone stock.
No need for power mods as I haven't used all of the stock power yet.
Bill, if you're interested in me doing some data analysis in Pi toolbox I think it would be interesting for everyone. I just need to get your MP4 file.
The brake gauge is percentage of pedal travel. If it ever goes to 100 it means your pedal is in the floor.
Actually, that happened to a forum member on Sunday. He was driving a modded Z51 going into Turn 10 Southbend and when he braked for the turn the pedal went to the floor. The PDR video clearly shows the brake meter being full red. He ended up spinning the car and colliding with the tire wall on the left side of the track. Pretty severe plastic damage on the right side of the car but he was able to gingerly drive it a couple hours home.
yes, sometime lower gears gives an illusion that we are going fast because the engine is screaming when in reality it slows us down (not to mention driving temps up)
With drag radials on my HCI C6Z from a 40 MPH roll I have found quicker trap speeds using 2nd even though going to 1st would pull to redline at ~66 MPH, so sometimes extra shifting only gives the illusion of speed as Bill finds in the Oak Tree turn using 3rd rather than 2nd.
10-02-2017, 06:01 PM
Personal Best Lap Time at VIR this Last Weekend
