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Old 09-21-2020, 07:29 PM   #201
sweetbmxrider
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I was told rule of thumb is as soon as you see smoke in the side mirrors, release line lock and then let off the gas. Should continue the burnout just a few more feet.

Does the data log show when you start the shift and when it completes?
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Old 09-21-2020, 08:27 PM   #202
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that makes sense yup. I have not been able to see the smoke in the mirrors, but I will try to look harder. I cant say that I have actually ever seen the tire smoke, but I know the tires are getting sticky since I come back to the pits with rocks stuck to them from the return road after the pass, but without me seeing a video its hard for me to know that my current burnout process is the right one for my application
-a guy on thirdgen.org pointed me to this info from Mickey Thomspon:
https://www.mickeythompsontires.com/...fication-sheet
yet, I have an auto trans and drag radials, so it says long burnout for auto trans, and short burnout for radials. hm....

Not sure what ya mean about start the shift and when it completes? If you mean when I physically move the shifter vs when the transmission slides into the next year, then the answer to that is no, the sniper software doesn't have a feature that shows that. If you mean the length of time I am in each gear, that I can actually calculate using the start/stop feature of the holley datalog software. I can probably even calculate how long I am on the damn rev limiter and get a good laugh out of that number.
-- The shift kit that is in it, is apparently the best one to use for a performance built 700r4 and my shifts are indeed firm and quick without being too unnecessarily rigid. https://probuiltautomatics.com/shop/...ied-shift-kits fortunately, the only issue I have ever had regarding shifting, is not the transmission, but me not reacting to the shift light or timing the dash tach needle.
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Old 10-11-2020, 12:35 PM   #203
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Short Version:

- Drove car to Atco
- Made 5 passes, best ET was 11.845 (pass 1) best mph was 115.94 (pass 5) best 60ft was 1.667 (pass 5)
- I have WOT ignition timing and AFR dialed in and set to perfection
- still working on finding optimal 1-2 and 2-3 shift points.
- nothing broke, nothing weird happened, car did its job
- packed up car and drove it home



Long version:

I decided to take the car down to Atco Dragway on Friday night for the Test and Tune. Rumors are that Atco might be closing its doors permanently as a drag racing track at the end of this season so I wanted to make some passes there as kind of a bucket-list type thing for myself. Atco is 2+ hours from me with no traffic, and despite me leaving my house at 1:30 pm, I still hit a bunch of NJ Friday afternoon traffic. I sat in traffic basically bumper-to-bumper for a good 45 minutes on rt 287 in Piscataway and the engine temperature never went above 191 deg. Made it down there right around 4:30 and unpacked my hundreds of pounds of spare parts, tools, a wheel, and misc gear. Went through tech, which was super easy and effortless. Got the tire psi, shocks, tune file, and fluids all set.

Pass 1:
6:18 pm DA was 669 53% humidity and 67*F. did a decent burnout
Launched from 920 rpm idle, converter flashed at 2,861 rpms. Shifted 1-2 at 6,567 (rev limiter) and shifted 2-3 at 6,072, crossed the stripe around 5,831 rpms. Checked my AFR readings, CL comp, and learn numbers in the file and those were great so I re-saved the file and used it the rest of the night.
- Had hoped that I would simply improve upon my timeslip as the night/weather got better, but just like several previous drag events at Island.. my first pass was my best timeslip of the whole night.. I don't know why that keeps happening to me!

video: https://www.youtube.com/watch?v=IptrSp8nSKQ








Pass 2:
7:51pm DA 195, 66% humidity and 61*F
-same tire pressure, same shock settings, longer burnout. lowered my shift light so I could try shifting at a lower rpm
Launched from a 937 rpm idle and converter flashed at 2,975
short shifted my 1-2 shift at 6,096 and then really short shifted 2-3 at 5,765, crossed the stripe at 5,537 rpm
short shifting the 2-3 really killed me up top, but the pass felt solid and the datalog traces looked good despite the pass being my slowest of the night

video: https://www.youtube.com/watch?v=gr2-uTHJZ2s







Pass 3:
9:37 pm DA was -39 with 70% humidity and 58*F
left the front shocks the same but tightened the rear shocks half-a-turn since my 60foots seemed a little slower than last month at Island. rear tire psi had dropped to 18.4, so I left it there. raised the shift light up a bit and also moved my rev limiter from 6,500 to 6,700 rpm.
- launched at 921 rpm, flashed at 2,770. Shifted 1-2 at 6,648 (rev limiter kicked in for a split second) and then shifted 2-3 at 6,377, crossing the line at 5,777 rpm. Noticed on the datalog (upper green line) that I was not at 100% throttle until I got into 3rd! wtf!

video: https://www.youtube.com/watch?v=OFhd0Bu5YmQ








Pass 4:
10:50 pm DA was -127 with 73% humidity at 57*F
aired up rear tires to 19.5 psi but had just a touch of tire spin off the launch. Tried launching at 1,300 rpm also. Did not get get a datalog this pass (must have not pressed "start"), but I know I short-shifted the 1-2 shift and revved out the 2-3 shift a little higher.

video: https://www.youtube.com/watch?v=38QnGeH7Y7s






Pass 5:
11:12 pm DA was -107 with humidity at 74% and 56*F
- launched at 922 rpm and converter slashed at 2,843 rpm. no tire spin off the launch and it was my best 60ft of the night. Short shifted the 1-2 at 5,902 and then shifted 2-3 at 6,353 which had me crossing the stripe at 5,641 rpms
- if you look at the top green line on the datalog, I was only at 76% throttle all of first gear and then i got out of the throttle a little bit for the 2-3 shift. Damn it Dave! somehow, this pass had my highest MPH of the night (and ever) at 115.94mph.
video: https://www.youtube.com/watch?v=JBTKBMuvggc









They shut off the track lights a few minutes after my last pass so I packed up my car of all the gear and aired up the tires just as they were shutting off the parking lot lights and closing the main gate. They had a track rental earlier in the day so I think everyone was just ready to close the gates and get done. Nice easy drive home on the highways with only a few weirdos pulling up next to me and trying to play around. The car ran great and simply put the torque converter lock-up ON and cruised on the turnpike for a long time doing 85 mph at 2,450 rpm and the engine temp stayed at 158-165*F the whole trip. Fueled up once on the ride home and pulled into my garage at 1:50 am. No leaks, no weird noises, no mechanical issues what-so-ever. Turned off the battery kill-switch, shut the garage door, went inside and passed out.




Overall, I am super happy I made the trip and got some timeslips at Atco before it potentially closes its doors for racing. It was well worth the trip and the fuel cost. I improved on my previous best ET which was 11.855 at Island last month, to 11.845 at Atco. I have the drag race tune file optimized for 35* timing at WOT and the target AFR for 12.5:1 at tq peak and then leaned out to 12.7:1 at the HP peak. The AFR is staying really dialed in (pink and light blue lines in datalog). The best 60foot times come from launching the car off of an idle and my drag radials at 19psi with a 2/5 or 3/5 rear shock setting. I would like to scientifically determine my optimal shift point. I am thinking about creating a separate forum post to discuss shift points and use science and math to help me (us) determine my target 1-2 and 2-3 shifts.

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Old 10-12-2020, 10:20 AM   #204
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Maybe check your throttle linkage and make sure you're getting WOT when you hit the pedal? Also check the TPS if the mechanical side of things is right.
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Old 10-12-2020, 10:47 AM   #205
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yep. its correct for sure. I just don't think I had my foot down all the way on some of those passes, like a fool. I went through a ton of the TPS and linkage checks during that few weeks in August/september when my MSD ignition took a crap. I made a few videos and stuff about it too, but the linkage and TPS readings are true. I've operated it by hand and watched the butterflies open to wot. Basically, I just wasn't on the floor with the pedal. you can see the upper green line in some of the other datalogs on this page (and previous pages) which will show my TPS gets to 100% pretty often.

But even if it didnt reach 100% apparently that is OK based on the way the Holley sniper is setup with a MAP sensor. According to Holley, anything over 85% TPS is considered full throttle. So in theory, if my throttle pedal is at 85% or 100% wide open, the engine/sniper would act exactly the same.
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Old 10-12-2020, 02:04 PM   #206
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True, but the airflow wouldn't be as the butterfly valve would be partially closed. In any case, now you know what to watch for next time around!
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Old 10-12-2020, 02:52 PM   #207
IROCZman15
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Quote:
Originally Posted by The_Bishop View Post
True, but the airflow wouldn't be as the butterfly valve would be partially closed. In any case, now you know what to watch for next time around!
So, I am glad you said that, and I fully agree with you on that. If the blades are not 100% open, there is a slight airflow restriction into the engine. I spent a lot of time reading how TPS, Map, and VE table info works for the sniper, ad while I understand the basics of it, I still have wondered about the butterflies. The more air in, the more fuel can be added and essentially the more volumetric efficiency and cylinder pressure I can make. Most people (my tuner in Texas included) have told me that WOT is WOT on a map system. I still think of it like you are, and that if my blades are not fully open, I am giving up VE. I am glad to be able to datalog and see it, otherwise without that, I would just "assume" I was at full WOT for every pass. The datalogs show that I was only at 100% TPS on pass 1, and pass 2, 3, 5 I had some throttle fluctuation. I probably also did on pass 4, but I didn't record a datalog during it.

-the more I look at the sniper tunes and datalogs, the more I want to get back out to the track and run the car again. I am probably going to type up a separate post/thread about scientifically mathematically figuring out my optimal shift points, so I will be asking for as much group input on that as possible. I know I am splitting hairs here in search of maybe shaving down another tenth of a second or so, but I am hoping for one more good track session before winter comes along.
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