First time to the track (12.97), track app not accurate and convertible roll bar...

[Thatguy]

For the time slip below, I'm car 100. I cut off the track info because I'm running a convertible and I don't want to chance getting their attention. Tech mentioned they would say something if I ran faster than 13.49 (no roll bar) but they let me go all night.

Performance mods are -
K+N drop in filter
Airaid tube
MAP intercooler
CVF charge pipes
NGK plugs from Tune +
Turbosmart Shortie Dual BOV
Turbosmart 10# WGA
MBRP 3" catted downpipe
Cobb Accessport with tuning done by Ryan at PD

This was my first time to the track with the car. Best run is below (12.97 @ 105.79). Stock 20" tires. I dropped the pressure in the rear to 27psi. The other ETs were from 13.00-13.17. 60' times ranged from 1.924-2.077. Every pass was at 105.xx MPH. DA was calculated to be -27'. I sent a couple of data logs to my tuner to see what he thinks. We're 7-8 revisions in. I usually send him 3rd gear pulls so this will be the first time seeing logs for full 1/4 mile runs. Each of them were done in drag mode. I felt that the car was shifting early on the top end. Looking at the logs I see that it shifts to 2nd at 6300. 2nd - 3rd happens at 5900 and the rest of the shifts are at 5700. I think the shift to 6th gear is the one I was noticing as being uneventful. Has anyone noticed their shift RPMs and do you think it will be beneficial to bump these up to around 6000? Convertibles are about 150-200lbs heavier than a coupe so that's close to 2 tenths there. ETs seem to be all over the place with these cars. I expected to be solidly into the 12s. Maybe consistent 12.70s/12.80s at 107-108 MPH.

I no longer have much confidence in the car's track app. I've used it on the street once in awhile. It's showed me a best 60' time of 4.6. I had a couple of 4.9s at the track. I felt it was hooking better there. It's also shown me 109 MPH after making a full pass on the street. The 1/4 mile app showed a 13.77 ET @ 103 when I ran 13.17 @ 105. 60' was a 1.92. The app showed 2.49.

Going back to the car being a convertible, does anyone here have one running faster than 13.49? If so, has the track officials said anything about a roll bar? I have a few things in mind to shave off a few more tenths but I don't want to put to much into chasing an ET when they can ask me to leave because of that ET.

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[DavidEcobeast]

You're ET seems about right with a 1.9 60ft.

I have similar mods and trapped just shy of 109 shifting around 6500 in Sport mode using the paddles. Bringing you're shifts up a little should help bring up the MPH a little.

 

[Thatguy]

Sticky tires would allow the car to launch harder so I think I could at least shave off two tenths with them. But I think there are at least two tenths in this setup before the tires. It's probably the shift points. If I know the shift modes correctly, I believe there isn't any significant torque management in drag mode. That's why the WOT gear changes are hard. Especially into 2nd and 3rd. Would lose that benefit with manual shifting but could gain from shifting later. The two combined would probably make it a 12.5x car which is what I was expecting from these mods.

 

[mJolnir]

just get a pair of hoosier drag radials and that same tune will go very solid 12's, shift points seem ok, but you can always ask him to let you test with 6500 shift points and see if you gain anything

 

[Thatguy]

I should have manual shifted a couple of passes to see what that did. I talked to Ryan at PD. We're going to finish the engine tune then work on the transmission. I've also been looking at drag wheels/tires. I've had good results with ET Streets in the past. I'll probably go with them and a set of 9-9.5" wheels. Still thinking about skinnies. They should be good for .10-.15.

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