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Old 09-26-2021, 08:11 PM   #395
IROCZman15
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Join Date: Dec 2004
Location: Roxbury, NJ
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I think that my detailed car update belongs in this thread and not in the nitrous thread because this is where I usually do my event/car recaps. The nitrous thread might get used specifically for nitrous system tuning and adjustments, but vehicle stuff I want to keep here.


So,

I street drove the car over to Island Dragway on Friday night for Test and Tune. Disclaimer, key words, test-and-tune.. that's all this was.. I was not going for any glory shots, but I did have some hopeful goals in mind for the test and tune session. I also told myself I did NOT care if I got a 30 second long reaction time today, i was simply going to leave when i was ready; reaction time was of zero importance. I had a few buddies who were there with me making some passes and a few other buddies who were there to spectate, so sometimes it was hectic in the pits. They only really ran cars for a few hours, as there were multiple long oil-down shut downs, and they closed the track about 10:20 pm instead of 11pm. I still got some good test hit in and drove the car home afterwards without any issues. Took the car to a local car show today, and I have been doing car shows the past 3 weekends also, bringing home some trophies, and putting several hundred miles on the car in the process. Very much enjoying all of it.



Pass 1:
All motor. Since I had not made any dragstrip passes since May 2021, I wanted to do an all motor pass just to get myself back into the routine of staging, launching, shifting, etc. The car is heavier now with the 6-point roll bar and harness setup. I am using the brand new Jegs SSR front skinny wheels which replaced my other cracked Jegs skinnies. Both weigh the same, but I just figured I would mention that these are the new wheels because there was some debate about the topic back in June on this thread. Front tire pressure was 48 and it stayed at 48psi8 all night long. Rear tire pressure was 21. Rear chocks were set at 3/5 setting , so medium, and front struts are a 90/10 lakewood drag shock which are not-adjustable. I am only launching off a foot-brake, no more 2-step limiter or anything, it messed up my afr readings/computer at the launch.
- I launched at 1660 rpm and the converter flashed at 3063 rpms. Shifted 1-2 at 6460 and dropped into 2nd at 4754rpms. Shifted 2-3 at 6476 rpms and dropped to 4846 rpms in 3rd gear. Carried 3rd gear across the finish line at 6265 rpms. Surprisingly, even with a heavier car, I ran an 11.84 at 115.5 mph, which is super close to my best runs from May 2021 which were were all around the 11.80 and 11.85 range. Also the 60 foot was right where it usually is, and the 8th mile a tad slow, but still in the ballpark. So that was cool and gave me confidence.


Timeslip:

notes( their date/time is way off. The date is off by a week, and the time is off by an hour, and it was off by an hour all during the spring season also.. would have thought they would have fixed this?!?!) The time and date on the bottom corner of my video footage is exact and correct.

Datalog:


In car video:
https://www.youtube.com/watch?v=fJ9JDggmGtw




Pass 2:
Had the 100 jets in the nitrous plate and I was ready to make a small PROGRESSIVE nitrous hit just to see that all systems were functioning properly. I had a slow ramp from 50hp-to-100 hp over the course of 2 seconds which I know is very uneventful. I have tested this on the street multiple times, but I wanted to do it at the track also. I launched the car at 1238 rpm and thats about all I have data for. For some undetermined reason, my datalog in nonsense (same for pass 3). The datapoints and data traces make no sense whatsoever. I did quickly hit the revv limiter at the top of 1st gear. I do know from memory that I did not spray until mid way though 2nd gear, so no nitrous in 1st gear. I then got off the nitrous for the 2-3 shift and back on it for most of 3rd gear. Therefore, my 60 foot, 330ft, and 8th mile are all N/A and my timeslip reflects that when compared to other N/A runs. My top end of the track shows improvement and I could feel the nitrous doing its job but I also felt it shut off when it reached the high-side rpm limits that I setup, so I got off the throttle just before the finish line, knowing that the solenoids and whatnot were flowing etc. Checked 3 spark plugs after this run and timing marks were good, no metal glitter on the ceramic, all looked good.

Timeslip:



Datalog NONSENSE:

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Video:
https://www.youtube.com/watch?v=wnbZx47ZbWo

Launch video:
https://www.youtube.com/watch?v=glI6mxj4k-U



Pass 3: With the datalog from Pass2 being useless, yet knowing the fuel/nitrous/ecu was doing its job properly, I decided to change from a progressive shot to a fixed 100 shot. I also lowered the rear tire pressure to 19 psi, but kept the rear shocks set the same at 3/5. The datalog is totally useless here, and I will be working with the Holley EFI forum guys to figure out if it's some wacky setting, or something I need to fix myself. I did not spray nitrous at all until the middle of 2nd gear ( you can hear it in the video) so therefore my 60 foot and 330 are N/A but then the 8th mile time/speed starts to get better. I got off the button for the 2-3 shift but then right back on the button in 3rd. Again, my high-side limit rpm limiter for the nitrous killed the nitrous at 6,100, so I was N/A from basically the 1,100 foot mare to the finish. You can clearly hear the engine pitch change when the nitrous deactivates and it sounds like its breaking up. This is exactly because as one of my safety parameters, I have the ecu delaying the timing 4 degrees (while the nitrous is on) AND for .5 seconds after the nitrous is deactivated. So its a safety feature, but I might shorten it up for next time, because the motor is not making good power 30 degrees in WOT when it has 200+ more feet to go before the finish line. SO, this is something i could not plan for while doing the tune, I had to have it happen in real life in order to find it out. I have a solution for all of this which I will elaborate on at the bottom of the page.

Timeslip:
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Datalog: what an insane looking datalog for a dragstrip pass!



Video:
https://www.youtube.com/watch?v=Yxlu5_pJ9oc


Launch video:

https://www.youtube.com/watch?v=oyU7Bt2UToc




Pass 4:
used the same exact tune, same shock settings, and dropped the rear tires to 17.4psi at the advice of my buddies. Had a proper datalog this time too!
They were calling "15 minutes until staging lanes are closed" as I was getting to the lanes.
Launched at 1,753 rpms (footbrake) and the converter flashed at 2,986. Nitrous came on at 3,500 in 1st gear and stayed on until 5,791 rpms in 1st gear. Shifted from 1st to 2nd at 6,571 rpms and it dropped to 5,020 rpms in 2nd gear. Nitrous was on the 100 shot all through 2nd gear, which I shifted out of at 6,585 and this dropped it to 5,082 rpms in 3rd gear. Nitrous was on all of 3rd gear until it hit my (newly increased) high side limit of 6,300 rpms where it shut off and I was N/A until the finish line at 6,597 rpms....with only 30 deg of timing for .5 seconds ...instead of my usual 34 deg N/A. Youc an hear it "break up" a few hundred feet before the finish line, but thats for the same reasons I listed above at the end of pass 3. This is why MPH is lower than it should be.


Timeslip:


Datalog:




Video:

https://www.youtube.com/watch?v=SxQ_V7aEEK0



Pass 5:

I had no time to look at the datalog or check plugs after this run. They were calling 5 minutes to staging lanes are closed as I was getting my timeslip. (look at the time difference between slips #4 and #5, and even though he hours are wrong, the minutes are right!) My buddies were all jacked up and said, you gotta get a 10 second pass tonight, so I did the only thing I had time for, and did a super quick nitrous jet change, from the 100 shot to the 125 shot jets. Pulled into the staging lanes and they are waving me to the burnout box yet I didn't have my helmet on or harness bucked yet! Slammed on my helmet and I was the last car to make a pass in the Race-tire lanes.

So, I did a healthy burnout and foot brake launched at 1709 with the nitrous button down. My low-side limit wont allow the nitrous to kick on until 3,500 rpms, and after the converter flashed (around 2860 rpms) I felt the nitrous come on. It shut off at my high side limit before I shifted out of first (at 6,502 rpms) and into 2nd where it landed at 5,208 rpms). sprayed all through 2nd gear until it clicked the nitrous off and I shifted 2-3 at 6,458 rpms and it dropepd to 5,175 rpms in 3rd gear. Sprayed all through 3rd until it reached the high side limit so it clicked off at 6,346 rpms and I muddled my way the last few hundred feet to the finish line, crossing at 6,456 rpms, with a freaking 10.99 at 122.5 mph!! WHAT IN THE HECK!!!


Timeslip:

(they had problems with their 60-foot cone so they turned it off. Some of my buddies also had .000 on their timeslip for the 60-foot but I would have love to know what it was. I am thinking like a 1.54, but without actual timeslip, I am just guessing)

Datalog:


Video:
https://www.youtube.com/watch?v=ffHSSKLSEMY


Full video with my reaction after reading the slip at 2:14 in the video. ha (and you can hear the announcer still calling "lanes are closed" at around 2:01 in the video)
https://www.youtube.com/watch?v=fxibcE8AEos




Took a while to chat with my buddies and packed up the car. All my gear was super wet from the fog and moisture/humidity. Drove the car home with a huge smile that things seemed to be working properly. Brought he car to the local quarry to weigh it in drag-race mode as compared to street mode. It weight in at 3,420 pounds without me in it and 3,600 pounds with me in it, yet only half a tank of fuel. So that is its race weight for the rest of this year. Would like to get it lighter over the winter, but WITHOUT compromising street, show, or autocross purposes.

Without me:



With me in it:




So, All in all, a pretty successful first nitrous TEST-and-TUNE session. My bottle heater did its job perfectly too. I have a few ideas for how to not just "coast" through the last 200 feet of the track, and one of them involves taller tires. I know I will certainly Do this for my next set of tires, but I won't be due for new tires until spring of next year. So, I am thinking, I might play around with getting on the nitrous sooner, and holding it through the shifts, which will put me at the top of 3rd gear just before the 1000 foot mark. And, while it sucks to have a 4th gear that is less than 1:1 ratio (in this 700R4), I can then shift into 4th gear and spray 4th gear for the last few hundred feet. It would be better than what I am doing now. Yet, there was no way for me to mathematically figure this out, until I physically made some passes. I also want to see if I can hit the nitrous out of the hole as I launch, instead of waiting for it to come on mid-way through 1st gear. Might really improve my 60 foot times, get me a wheels up launch, and I would like to see if my suspension takes it. As it is now, from the launch videos, it looks like I could crank the right rear shock a bit tighter to a 4/5 and leave the drivers side a 3/5. There is also air-bags for the springs too as an inexpensive technique, but that's only if I do have launch issues while launching on the button. I also WILL be throwing a bigger nitrous shot at it in the coming weeks, so there is no doubt in my mind that I will have to shift into 4th gear. I'm thinking the car has the potential for a 10.75 pass around 129 mph before the year is over on a bigger shot.
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1987 IROC-Z - modified

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