A few of my buddies were going to the Friday night Test-n-Tune at island on Sept 22, so I jumped in on it. However, I had to thrash beforehand to swap the Boze wheels out for the drag wheels, and also swapped out the Koni yellow front struts for the lakewood 90/10 drag struts. I pulled off the front swaybar while I was underneath there too. I did not have time to swap the rear Koni shocks, and this actually was going to serve as an experiment like Townsend suggested a few months ago, that perhaps I could make my Koni's work better than the non-adjustable lakewood drag shocks. I had not been to the dragstrip since May 28 and I also wanted to see how my dyno results might come into play.
Pass 1:
I was curious to see if the small "gain" in hp that we saw on the dyno when going from 35 deg timing to 37 deg timing would play out. I tried to datalog from the laptop via the usb cable, but I guess I never hit the clipboard button to start logging, so there is no datalog. It was a simple all-motor, 37 deg timing pass. Footbraked to about 2000, went a fast 1.48 sixty-foot, I was clean on the shifts, it just felt like it lost power up top and therefore lost 4 mph (113mph) down from the usual 117 mph. So, either I won't be doing that 37 deg again, or if I do, maybe it would only be with racegas additive in there. The car has always seemed happiest at 34-36 deg WOT anyways, so this was just a test because of what was learned on the dyno.
video:
https://www.youtube.com/watch?v=nc5HFMj3Pnc
timeslip:
no datalog
Pass 2:
Had the 150 shot jets in there. These had just made everything go really rich on the dyno, but in my street/strip use, they have not ever done that, so I needed to re-try them after the dyno. Tried to datalog to the SD card, and that turned out bad, so there won't be any more of that. I need to find a reliable way to mount the laptop in the car and keep the usb cable connected to laptop during its mph pass down the strip. I hate having it fly all around the floorbaord, but that seems like the only way I will get useful datalogs with data points I can read. velcro and some clips maybe?
Anyways, launched from about 2200 and it went hard to the sixty, with a 1.44. I still always feel that slight amount of tire rotation/slip, more about that later on. The car pulled good through the 330 but then the jetting went lean and we were off the spray before the 1/8 mile. I rode out the rest of the pass but now my head starts spinning because its running way lean, not rich!
video:
you can hear it eat itself up right after the 15 second mark. also, that BMW running 9's was fast !
https://www.youtube.com/watch?v=Au2P_AN1cDQ
timeslip:
useless datalog:
Pass 3:
They were calling that the lanes were closing soon so I checked a plug but didn't have time to change the fuel jet (that one takes a while as its in a real hard spot). What I should have done, was just swap out the nitrous jet for a smaller one, since that only takes a minute to change. I did swap back to a 150 shot street-use tune file that I had saved. Anyways, The laptop recorded a nice datalog with datapoints I can use. launched from 2207 rpms, but rolled into the throttle a little slow. So the nitrous didnt come on until later (when TPS was 80% the rpms were at 4900). it still went another 1.44 sixty foot, but I still feel that slight tire slip at the hit though. It still went lean after the 1-2 shift which was 6491 dropping to 5280. With the nitrous off, I pedaled the throttle and let it gather itself up, then early shifted 2-3 (at 6054 dropping to 5305) and finished the rest of the pass on motor ending up at 5906 rpms.
video:
https://www.youtube.com/watch?v=UIKRIeu3uA4
timeslip:
datalog:
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the tire markings:
After that third pass, while packing up, we all couldn't help but notice the markings on the drag radials. I was surprised, because this can't be from a low tire pressure situation. I have previously gone as low as 16.4 psi on other dragstrip days with good numbers in the sixty foot, yet have never seen these show up. Today, every pass I had the tires exactly the same, at 18.6 psi. From previous test days, I usually don't have a good launch if I am higher than 19.5 or so. Thoughts? Part of me is wondering if the tires are hooking, but I might have an issue with the rim/barrel of the wheel spinning in the tire? Next time I am going to paint-mark them and find out for sure. But, for a good long while now, I've felt that small "slip" at the launch and nobody sees the tire do it, so perhaps its the wheel/tire bead? Not sure.
John's first hit with his new setup.
https://www.youtube.com/watch?v=SUK3lhXJF3Q
