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Old 04-18-2022, 09:04 PM   #481
IROCZman15
10 Second Club / Meet Coordinator
 
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Join Date: Dec 2004
Location: Roxbury, NJ
Posts: 2,100
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It has been a while but I do have an update.
Despite the several times I wanted to go to the track in March and April, the repeated bad weather and rain-outs didn't allow my spring shakedown of the car to happen until just this past weekend. Even the swap meet I wanted to go to, got rained out. Anyways, prior to going, I had done some street driving and street rips with the car and was moderately "ok" with the AFR numbers I saw on both the Holley and the new AEM gauge. The car felt pretty slow on the street and I had done datalogs and tune revisions several times. Basically I would do a pull in 2nd or 3rd gear, and the car was real rich at tip-in and stayed that way while sloooowly climbing the rpms. Adjustments to the base table and AE were never really fully successful, so I went into the Test and Tune Friday night at Island Dragway with pretty low expectations . However, I knew that if I got a few actual WOT dragstrip passes, I could probably dial in the tune better. Jerry and my buddy John went to the track too, and Jerry brought the firebird. I had hoped to get about 5 runs on the night but that plan came to a halt when a huge oil down happen just after the first few sets of the cars went down the track. That cleanup took 1 hour and 50 minutes, so basically 2 hours of a 4 hour race night were gone and I didn't have a pass in yet, and temps were going down as well as track surface temperature.









Pass 1:

Finally got to make my first pass at 9:21pm, and it went pretty well surprisingly. I had set the brand new rear MT tires at 19.5 psi. Air bags were at 7psi drivers side and 11 psi passenger side. Rear shocks were both set at 4/5 so on the tighter side. After a 3.5 second burnout I footbraked the launch from 1109 rpms. Rear tires had a very slight slip, but then hooked and I shifted 1-2 at 6,490 rpms. rpms dropped to 4,816 in second gear and I shifted a bit early at 6195 rpms. Rpms dropped to 4,772 in 3rd gear and then I crossed the finish line at 6,069 rpms. I was targeting a 12.8 AFR in closed loop and total timing was 34.0 deg advances. The car felt good, and it didnt do anything funny, but I expected a low 12 second slip. Was certainly surprised to see an 11.78 e.t. at 115.7 mph, which is actually my fastest N/A pass to date (previously was 11.800 back in november 2021)
-Checked the datalog and was happy with what I saw, but knew I might only get 1 or two more runs in for the night. the fueling still went rich at the hit, like very rich (in open loop), but as soon as closed loop came on, it cleared it up and I looked over the CL comp numbers. I would love to get that rich dip out, but pulling fuel from the base table (open loop) and the AE functions still doesn't seem to help?

Video:
https://www.youtube.com/watch?v=EswZSWsQqP8



Timeslip:






Datalog:






Pass 2:

I was satisfied enough with that NA pass but I know I could improve on it NA later on in the coming weeks. Did not pull spark plugs, maybe I should have checked a few. I wanted to see how a nitrous pass would do and I had to decide if I should do a fixed 150 shot and see if it would hold the launch, OR do a progressive ramp. i decided to try the fixed 150 shot knowing if I got a 3rd pass I could load the progressive tune in and make adjustments if needed. Jerry jumped in the gamblers $ race and John was running his Envoy because his silver 3rd gen TransAm is still not up and ready. Jerry video: https://www.youtube.com/watch?v=nv-F-gifsWs

With the 150 shot tune loaded, I kept the shocks and air bags the same. I lowered the rear tire pressure from 19.5 to 18.0 psi. Did a 5 second burnout. I launched from a dead idle at 921 rpms. The nitrous came in withte full 150 shot mid way through 1st gear (as I set it to do) and it spun the tires. I pedaled it very quickly, got off the button, and then got back into it, shifting 1-2 shift at 6,611 rpms. The rpms dropped to 5,272 in second gear. Took second gear to 6,607 rpms and it dropped to 5,023 rpms in 3rd gear. Nitrous turns off at the shifts if I hit the hi-side 6,500 rpm limit I pre-set. I crossed through the finish line at 6,510 rpms which was just a fraction of a second after the nitrous clicked off.



Video:
https://www.youtube.com/watch?v=cpEYRY72Cp4


Timeslip:





Datalog:





pass 3:
I now knew that I would have to wait until another day to test the full nitrous launch, but I looked over the datalog and aside from the spin in 1st gear, I was happy enough with the AFR numbers that I saw. I target 12.4 afr on nitrous and the holley adjusts CL comp to this. My AEM gauge is usually a bit richer with the readings, in the 12.0-12.2 range if the holley is reading 12.5. (still not sure why..) So at this point in time, I am happy keeping the afr rich (safe) and then working from there as opposed to running it lean and dialing it back. I loaded the progressive 150 nitrous tune in, which ramps from 50%-->100% in 1.2 seconds (essentially spraying a 75 shot ramped to a 150 shot in 1.2 seconds; see below) I also increased the rpm rev-limiter for the nitrous cut-off to be at 6,700 rpms instead of the 6,500 rpms from last run. John advised I try the other lane and that I take more psi out of the rear tires so I brought them down to 17.0 psi.
- I did a decent burnout, but as I rolled to the line I did not see that the guy next to me had pulled way past the line and started staging with his back tires. At this point I was already staged, while they rolled him back. I probably could have rolled back out, but I decided to just stay where I was at. He finally got it sorted out and when the tree dropped I left from an approx 920 rpm idle again. I felt the tire slip (maybe like 1/3 of 1 rotation, not too much), but then it was allll good. unfortunately the datalog recorded very stupidly and it only has very strange intermittent data points. the log started recording normal, and even ended normal, but the whole middle, it only seemed to record about 1 data point every half second. So I have no data on shift points, rpms, fueling, closed loop compensation, or anything. That especially is sad, because this is data I wish i had for the future, because this turned out to be my best pass to date, with a 10.77 at 126.7 mph !


Video:
https://www.youtube.com/watch?v=sUphOhmyzqk
-***- watch this video until the very end for a weird surprise as to what I saw happen!


Timeslip:



Datalog (if you can even call this nonsense a datalog?!?!)


(entire datalog) see how it starts and ends with LOTS of data points, but gets "dumb" ? what the heck is that about?!?1


progressive nitrous tune settings/limits/timing:


and






I did NOT expect any personal best timeslips during this shakedown-session , but I am ok with how it turned out. The personal goal I set over a decade for this car was mid-high 10s on nitrous and mid-high 11s on motor. If this car can pull a 10.55 timeslip at 130 mph, I will consider that as "goal accomplished", so I am hoping I can get there. Maybe on a day with a sticky track for a great launch (and wheelie) and i can up the jets to the 175 shot or the 200 shot. After hanging out with the fellas in the pits, I packed up and drove the car home, thumping into the garage at 12:30 am with a sense of relief that the car didn't do anything dumb after a big winter of garage work.






The next morning, with the tools removed from the car, I took it over to get an approximate "race weight" on the car at the local stone quarry's scale. With me in the car it weighed 3,620 pounds, which is heavier than last year. Later on in the day I switched the race wheels out, put the subwoofers and amplifier back in the car and weighed it in "street weight setup" to learn that it weighs 3,780 pounds with me in it.






While looking over the car remembered that I had heard a clunking noise from the back of the car when going over some bumps on turns. Soon noticed that it looks like the "roto-joint" end on the axle side of my UMI Panhard bar is experiencing some wear and clunking. It was hard for me to film it and shake the car at the same time, but you get the idea
video: https://www.youtube.com/watch?v=dmgMg8miHmI
I guess I will call/email them and see if it is salvageable, or if I need a new joint.
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1987 IROC-Z - modified


Last edited by IROCZman15; 04-18-2022 at 09:40 PM.
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