Using this DA calculator (http://wahiduddin.net/calc/calc_hp_dp.htm) and these hourly historical weather conditions (www.wunderground.com) you'll see that even the 90%+ humidity really bares no effect on the calculated DA when the temps are so cold and the baro pressure is so high. Even with a 26 degree temp, 93% humidity, 30.12 baro, and a 550' elevation, the DA is still nearly 1,800' below sea level and 107% relative HP and 105% relative air density. Even if the humidity was cut to 50%, the DA hardly changes.

You're right in saying that the calculator can't take into account launching, but it sure looks to me like your track was prepped pretty good for you to be getting fairly decent 2.1 60 foots on low profile 18" tires in 26 degree weather.

IMO, the conditions (DA and track prep) and a little weight reduction played the most significant roll in the ET drop and MPH increase. You've raced enough times to know what you're doing now. And you're right, you did have a killer night.

I know for a fact that conditions (DA and track prep) are solely the reason why my 03 5AT sedan with a Z-pipe went from 14.49@97.5 with a 2.21 60 foot in May to a 14.32@97.8mph with a 2.15 60 foot a couple weeks ago. The DA between race days went from 1,800' in May to around 100' in late November. No additional mods, no weight reduction, the same shift points and launch, etc. The conditions alone was good for nearly .2 seconds and 1mph, overall when comparing slips.

 

Trey,

at what RPMS do you shift? I am still playing with shift points on my '05 6MT Sedan. my best has been a 14.3 @ 99 with a 2.28 60'

 

Not to argue with you - only to point out what I found - I put his info into the calculator that we used from the previous trip with the track conditions from last night. Obviously the conditions were not the same but I wanted to compare the times under the same weather conditions. Make sense? Anyway, when this was done the corrected times for both runs still showed a difference of 3 tenths of a second in favor of last night. I also found it very interesting that out of 3 sites that I went to in order to get information regarding the weather at specific times they all reported different conditions. Sort of irritating really. Besides the track is 12 miles from the closest "readings" that were listed and it is out in the middle of NOWHERE and I mean NOWHERE so there is no increase in temps because they were in the "inhabited" areas. LOL

 

I am not disputing that conditions played a role. But the temps were just under 10 degrees lower this past friday versus the previous week. During that time, I improved my time by 3 tenths. 8 to 10 degrees is not going to do that.

Using wunderground:
At 12:35 AM, Saturday, November 26th (roughly the time of my 14.09@101.6 from last week), the conditions were 30.2 degrees, 93% humidity, and a baro of 30.21. Those conditions yield a DA of -1501 feet. My 14.09@101.68 corrects to 14.28@100.29.

At 12:55 AM, Saturday, December 3rd (roughly the time of my 13.791@102.22), the conditions were 26.6 degrees, 86% humdity, and the baro was 30.12. Those conditions yield a DA of -1666 feet. My 13.791@102.22 corrects to a 14.00@100.69.

Without the corrections, I saw an improvement of 3 tenths. *With* the corrections, I still saw an improvement of 2.8 tenths. Using these numbers, the lower temps resulted in an improvement of 2 hundreths of a second.

As a further example, correcting my previous run of 14.09@101.68 with last nights conditions results in a 14.3@100.16. So there I *still* gained 3 tenths.

To summarize, the conditions helped. But only marginally. We're not comparing 26 degrees to my first runs at 98 degrees here. We're comparing 26.6 degrees to 30.2 degrees. It's just not that big of a deal.

 

I was very specific in my shift points last night. I shifted from first at 7100rpms. I shifted from second at 7300rpms. I shifted from 3rd at 7300rpms also. No variation.

I'm tempted trying to shift from 3rd at something lower like 6600rpms. Just to see what the sweet spot is.

I'm not working with any shift point calculators. I'm going by trial and error.

 

Here are scans of the 13 second timeslips. Yes I am deliberately ignoring the other, slower runs

 

Dave you're worse than me. Were you checking into Treys historical weather conditions at his track to make your calculations?

 

Congratulations on your times.

Do you think the Crawford Cats had any impact on your times?

I remember reading about your Kinetix horror story- I hope the Crawfords have given you good fit/performance.

 

thanks....I'll have to try shifting higher next time I'm at the track.

My best mph has been 99.16, but I've shifting closer to 6600 (on the factory tach )

 

Okay, I pretty much agree with you. I still think track prep played a decent roll though because you're trap speeds (once corrected) didn't really improve. Didn't your 60 foots improve by over .15 seconds on average? That alone can account for about a .2 to .25 second drop in ET.

Were you using your same launch style as last time?

 

14.3@99 is not a bad time. What were the conditions? If that's in orlando summertime heat and humdity, then I am pretty impressed. Though a trap of 99 means you could get a 14.2 with out much effort, and maybe a 14.1 on the low side.

But I gotta tell you that that 2.28 needs to come down. I don't have much room to speak, I still regularly get 2.2's. I've never had much success launching, especially with any consistency, until this last trip.

Have you run with the MREV yet?

 

I have no idea what impacts the crawfords may or may not have had. About a month ago I established a new PB of a 14.16@100.6, and that was with my OEM goodyear summer tires and the kinetix cats.

Last week I bettered that by only 7 hundreths of a second, but that was on kumho all-seasons and the crawfords.

The last time I dyno'd the car I had the kinetix on. I plan on dyno'ing again prior to installing the MREV. Unfortunately the next dyno will not be comparable to my two prior dynos, because I plan on trying another shop(better reputation with the local scene).

As for a comparison between the two types of cats, you can take this with a grain because my sets of cats may not have been representative of the whole. When I put on the kinetix, I absolutely loved the sound. Great sound. Awesome. And they were roughly a third of the weight of the stock cats: ~5lbs versus ~15lbs. At first I thought I felt a small loss of low-end torque, but it was so small it could have been my imagination. As for high-end, I couldn't distinguish a difference. When I put the crawfords on, I was a little disappointed in the sound. Otherwise sharing the same exhaust components, the crawfords were roughly 75% of the volume of the kinetix. The crawfords have a *slightly* deeper tone, but even to a few friends at work the kinetix had a more "euro" flavor. But on my first drive after I put the crawfords on, I immediately noticed a decent punch below 4k rpms. Not *huge*, just back to what I was used to. And this was without letting the ecu adjust.

As for fit and finish, I thought the crawfords were better made. They accomodate the stock cat brace, and they have integrated headshields.

As for power, I don't know what to attribute it to, but right now I can break loose the rears when shifting from 1st to 2nd as low as 4500 rpms, and I've never been able to do it that low before.

 

how are you shifting at 7300, the stock rev limiter is at 6600 and even with the technosquare they raise it up to 7100 i thought, still nice times, yeah i was running with Quadcam the other night here in orlando, in my new to me 2003 350z 13.9 at 101. i only have a K n N drop in and skunk2 plenum spacer, with crappy 2.2s. they call the track here Orlando Spinworld for a reason.....

 

trey,

not in the summertime heat.

My 14.3 @99 was in 50 degree air in orlando. That time is with the MREV.

Launching has been difficult for me; my clutch is shot; On the previous run, I lost the clutch in 2nd gear.

I'm looking into clutches now.

 

.... in the wet humid foggy Florida 50 degree air.... sorry had to add that