Strip times analysis, please!

[SoundGuyDave]

Okay, something is just plain wrong... Last month I went to the track and ran the following best:

60' 2.033
330' 5.676
1/8 8.665 @ 82.72MPH
1000 11.253
1/4 13.459 @ 101.93MPH

The only mods at that time were a CAI/tune and 3.73 gears, NO lightening.

Today, the best I could do was:

60' 2.034
330' 5.746
1/8 8.811 @ 80.56MPH
1000 11.449
1/4 13.703 @ 97.79MPH

With the following mods: BMR springs, UCA, LCA, sways, panhard, D-Specs, Steeda bump-steer, 18x9.5 rims with Nitto 555's (255/45 front, 285/40 rear), jack and spare pulled. Front tires at 35psi, rears at 27psi, front struts at max soft, right rear at full firm, left rear one turn back from full firm. Also, have Steeda CMCV delete plates (with a new tune, of course), and Roush underdrive pullies.

May's weather was 78 and dry, today was 93 and 90%, so I'm sure I lost a bunch in the air. Since this was a club outing, I was running against the same people, and in general, EVERYBODY was running around 4/10's to 5/10's slower than last month. Based on that, I theoretically picked up about 2/10's, which seems quite low for the mods. I lost 4MPH, but the average loss was only about 2MPH.

The "butt dyno" is telling me that I'm launching harder with less wheelspin than last month, but the 60' times really haven't changed, despite the suspension and traction work that has been done. And yes, before you ask, the car was aligned post-install, and the pinion angle is -1.9 degrees, with a 0.01 degree thrust angle on the rear end, and less than 1/32" wheelbase differential. Front camber is -1.5, with 1/16 toe-in total, with rod-end tierod ends.

Could the weather have hurt the tune THAT badly? Would it affect the 60' times that much? I was hoping for 1.8 60's, and I'm clearly still above the two-second mark.

One of the cars I raced was another '06 auto, (ran twice), with nothing more done than a K&N CAI and tune flash. Here are the times:

RACE ONE RACE TWO
-----------HER-- ME------- HER -- ME

DIAL -----13.99 --13.79 ---13.99-- 13.79
RT -------.092 ---.355 ----.275 ----.606 (ouch!)
60' -------2.185-- 2.118--- 2.243-- 2.071
330------ 5.937-- 5.826--- 5.992-- 5.791
1/8 ------9.009--- 8.862--- 9.053-- 8.836
MPH -----80.34 ---82.64--- 80.82-- 82.23
1000 ----11.641-- 11.495-- 11.671 -11.475
1/4 ------13.887- 13.773--- 13.901 13.720
MPH -----99.80--- 98.56 ---100.52- 98.36

Since we're both autos, and are "foot to the floor" from end to end, I'm still scratching my head as to how the other car beat my MPH, particularly since IN THEORY, I'm making a handful more power, and with a taller gear to boot... I don't have the slip handy, but last month, we were within .01 seconds of each other...

Any thoughs or observations (excepting "give it up") anyone may care to contribute would be MUCH appreciated. I know that I'm carrying more unspring weight now, and more rolling resistance, but I'm also supposed to be making more power, and I did shed a good 30lbs worth of spare, jack, and gak, and 3/4 of a tank of fuel...

I know that I would benefit from drag radials, but this was a street-tire to street-tire comparison.

 

[psfracer]

Well, you already answered PART of your question, which is the air. Also, the air will effect your 60' as well.

Now, here is the part that concerns me---which leads me to believe something is wrong.

Look at the 1/8th mph of the other car: 80.34 and 80.82----both of which is lower then YOUR 1/8th mph which was 82.64 and 82.23. So if you were almost 2mph better at the 1/8th, how could the other car (which if I understand, has less mods, fighting the same bad air as you) beat your 1/4 mph by 2mph? 99.80 and 100.52 vs 98.56 and 98.36?

Also, it is normal to expect a 20mph increase from the 1/8th to the 1/4 mile on N/A cars. Her car was doing this--19.46 increase on run 1 and 19.7 mph increase on run 2. YOUR cars increase was 15.92 on run 1 and 16.13 mph run 2. Something is wrong on the big end in addition to what you already know about the bad air.

 

[don_w]

That "nosing over" after the 1/8 is exactly what mine was doing the last time I ran a full 1/4-mile (last Oct at FFW Fontana). In 90 degree air and a DA of 3,058, I went 7.26 @ 93.6 to the 1/8, but only ran 11.47 @ 114.9 at the end. I would have expected an ET of around 11.30 and higher trap speed (closer to 120). The car just wasn't pulling hard on the back half. Subsequent diagnosis reavealed a bad torque converter that wasn't locking up in 4th gear.

 

[SoundGuyDave]

That "nosing over" after the 1/8 is exactly what mine was doing the last time I ran a full 1/4-mile (last Oct at FFW Fontana). In 90 degree air and a DA of 3,058, I went 7.26 @ 93.6 to the 1/8, but only ran 11.47 @ 114.9 at the end. I would have expected an ET of around 11.30 and higher trap speed (closer to 120). The car just wasn't pulling hard on the back half. Subsequent diagnosis reavealed a bad torque converter that wasn't locking up in 4th gear.

Ah, crap... not what I wanted to hear... I just skimmed through Hawg's service manual stickey, and I didn't see any diagnostics on the AT. Do you remember specifically how the 4th gear lockup was diagnosed?

I'm a little suspicious of my tune, as well. All was good until I installed the CMCV deletes and the new tune from JDM, and then things felt wonkey. Trans shifting a lot softer, the engine feeling flat above 3500 revs, etc... Jim put it down to the computer not being settled in yet, and asked me to keep driving for a day or two, which I did. The shift firmness came back, but not the top-end pull.

If the trans diagnostics are simple, I'll shoot for that to prove/disprove the theory, but if they're involved (compressed air in the valve body, etc.), then I'll pull the deletes and reload the old tune, and see if the "feeling" comes back. I though the deletes lost a little on the low-end, but added up high? I'm getting the opposite feeling.

Thanks for the help!

 

[don_w]

I'm not saying that a bad TC is your problem... just that mine showed similar symptoms. And the "diagnosis" took place a few weeks later. I was at Adam's shop for a Mustang Dyno Day. When it was ready to go on the rollers, he went into the tune to lock the trans in fourth gear for the pulls, but the converter would slip under load. That was last December, and I still haven't replaced it.

 

[psfracer]

Don, the PI converter is definitely worth the money---the best the Art Carr converter could do was a 7.49---the PI converter with no other changes ran a 7.25, I improved .24 in the 1/8th!

 

[SoundGuyDave]

Don, the PI converter is definitely worth the money---the best the Art Carr converter could do was a 7.49---the PI converter with no other changes ran a 7.25, I improved .24 in the 1/8th!

Just a few questions, PSF... First, thank you for confirming for me that SOMETHING is amiss with my setup... With a converter installed, how does it affect the drivability of the car? Last car I had with a converter was decades ago, and it was a pig on the street (no lockup clutch, 4K stall with a 351C in front of it...). Mine's primarily a DD application, and part-throttle cruising is the norm, not wide-open 1/4 mile blasts... Can you think of any tests I can do to positively confirm my AT function? If I broke it, I obviously have no problem fixing it, but I really don't want to throw parts at it if it's something else...

Also, my apologies for not posting this in the correct forum to begin with! I have the main page bookmarked, and when I got home, hot, exhausted, and frustrated, well....

 

[don_w]

Don, the PI converter is definitely worth the money---the best the Art Carr converter could do was a 7.49---the PI converter with no other changes ran a 7.25, I improved .24 in the 1/8th!

Yea, I totally agree. Replacing the converter is next on my list of things to do. Unfortunately, between buying four new street tires (plus a new pair of slicks), the roll bar, new rear gears, and the stuff Adam is doing, my "fun money" is tapped for a little while. In fact, I told Donna just last night that I plan on getting the TC replaced before FFW Fontana in October. That's likely the next time I'll see a quarter mile track.