Out to the dragstrip yet again...

[J-Rod]

I went out to HRP last night for the Wed night bracket program. We had a bit of a cool front blow in over the last two days. I had hoped it might hold, and I could get in a couple of good runs before the weather goes to "Texas hot" and I have to wait until the fall for some more good ETs.

Of course, this was not to be... When I got out to the track the temperature was 83. Humidity was 68% and the barometer was 29.97...

The track seemed to be prepped decently. My first pass was a 1.954 60' but the ET was WAAAAY off 12.417@114.36. As usual my first pass was a blow off pass. I got the car to 60' ok, but I didn't keep the revs up, and the car bogged a bit. I weighed the car, and with me in it it scaled @ 3229. Also, I hadn't had a chance to cool the car, so when I staged the water temp was @ 209.

The next pass was a bit better. 1.877 60' 12.170@115.15 But still dreadfully hot outside.

The next pass was the best of the day

60' - 1.789
330 ' - 5.092
1/8 - 7.814
MPH - 91.21
1000 - 10.143
1/4 - 12.106
MPH - 115.06

I was racing a Pantera that pass (who red lit) and ran a 1.759 60' 11.994 @ 114.77

The next pass was a 1.811 60' 12.141 @ 114.85

By now, the car was heat soaking pretty badly ( I don't have a fan switch yet). Not only that, but the sun was beginning to go down. I had hoped that a temperature drop would bring my ETs down. By now it was 7:39PM The next pass was pretty indicative of the rest of the evening. The pass sucked. It was 81 degrees outside, my water temp was at 212 on the line The leave sucked and I spun. 2.086 60' 12.603@114.63.

At 8PM I went and checked the weather station 77 degrees 68% humidity 29.97 on the baromter. As the temp went down, humidity began to go up, and the track began to go away quickly. Plus my clutch was beginning to get to hot to be effective.

My next few passes were awful. All of them ended up with either wheelspin or leaving like a pig.

2.092 60' / 12.571@114.10
2.165 60' / 12.717 @ 114.42
2.091 60' / 12.533 @ 114.71
2.187 60' / 12.638 @ 115.12
2.047 60' / 12.406 @ 114.68
1.975 60' / 12.368 @ 114.18

My last pass was @ 9:56 PM. By this time the track was totally gone, and so was the car. It was hot, the clutch was hot, and so was I. So, I just packed it up, and took it to the shop. Supposedly Saturday is going to be cool. So if things permit, I may try to get some passes in on Saturday.

The thing that is getting me most at this point is the clutch. This time on any hard leave, the clutch was staying on the floor. My best pass was made by launching @ 5200 and riding the clutch. I really would like the clutch to come off the floor, as I don't feel like this is the hot ticket for ETs or clutch life.

So, I guess we'll see what happens there. I am considering a modified line/ MC setup to help with this. If not that, it may be time for a better clutch.

[timgt]

What mods do you have? stock tires? 12.10 is pretty good if you are stock, I don't see any mods listed in your post. I ran last weekend and got a 12.30 @ 116, so my mph is a little higher then yours but you got better 60's (mine was 1.9's) I also don't ride the clutch though. I have a Halltech T1 as my only mod as of now.

[2002 Z my 6]

J-Rod, what kind of ET variability are you seeing with changes in temperature. For example, how much time do you lose when the temperature is 90 rather than 80?

I will be at HRP on Sunday. The forecast calls for a frigid Houston high temperature of 78 degrees. I'm hoping to improve my rather embarassing times that I set three weeks ago in 90 degree weather.

[J-Rod]

As listed in the msg. My car is 100% bone stock. Stock air filter, etc...

Temperature, humidity, and barometric pressure all work together to either increase or decrease power. That is why everyone is always talking about corrected dyno numbers. On a good air day in Houston my car makes 358 corrected HP, but 374 actual. Or roughly, 405 corrected at the crank vs 430 actual at the crank.

There are several facotrs out there to calculate HP gain/drop.

But as an example on a better air day, my car ran an 1.85 60' 11.933@114.52. Yesterday I could only muster a 12.10. So the air/humidity/barometer + track prep was worth at least .2 maybe closer to .3

[BLU-BY-U]

I will be there this sunday. The weather looks promising with a high of 80, low humidity, and I would bet a decent baramoter.

see you guys there!

Jeff B

[2002 Z my 6]

Jeff and J-Rod, if we find each other at HRP, I'd love to record data from your runs. I have a device the will record acceleration data. I run the data through a spreadsheet that I developed, and out comes data like this:
AP-22: An Accelerometer for the True Gear Head/Tech Geek
. For comparison and learning purposes, it would be nice to have a few of your fast runs recorded. I plan to arrive before the gates open. I should be with a pair of Z28s and a WRX wagon, and I usually park near the staging lanes.

It will take me a few passes to complete the calibration of the unit. After that, it would take two or three minutes to hook it up and show you how to operate it. Hope to see you there.

[PowerShifter]

J-Rod, You have BIG ONES launching in the 5K range!! I don't think the stock clutch can take that for long. But I my be overly concered, I just have no interest in haveing to change mine. So for now the 3K range is reserved for special ocasions with mine. Ric

[J-Rod]

Hey guys...

2002 Z my 6 - Sorry I missed you. I saw you leaving when I got there. I usually get out there late, so that the air temps are down.


BLU-BY-U It was nice meeting you.

PowerShifter - What else can I say but . Seriously, you are right. The clutch can't take that kind of abuse. I am not getting any real "stink" off of it. But after a few hard passes you can smell it just a little bit.

The thing that bothers me the most, is that the car is capable of moving harder on the stock radials. The clutch just won't take it. As soon as it starts to grab hard, the clutch sticks to the floor. Seems like there isn't enough clamping force combined with the restriction in the M/C line.

I went out Sunday since the air temps cooled down and made 6 more passes. With the drop in air temperature from 83 Wednesday down to 75 Sunday when I go there and eventually getting down to 63 at about 10PM. I felt like I might see some improvements in ET.

My first pass uncharacteristically was my best one. The airteps were 75^ and the car weighed in at 3239. I took it "easy" on the lauch and launced around 4000 rpm. As usual the clutch stuck halfway down. In fact, in all my passes Sunday the clutch acted stupid.

Anyhow, here is a synopsis of my best timeslip.

60 - 1.854
330 - 5.074
1/8 - 7.751
MPH - 92.32
1000 - 10.055
1/4 - 12.007
MPH - 115.23


The next few passes were not really all that spectacular. The next one was launching at 5200 RPM. The problem with launching there is that the car will move out, but it seems to nose over a bit as the clutch is trying to lock up towards the top of 1st. The pass netted a 1.978 60' / 12.234 @ 115.22. The next pass was a bit better 1.952 60' / 12.090@115.73. The next pass felt really good until I did something I have never done... I missed 4th. I crunched it pretty good and felt really stupid. I netted a 1.884 60' / 12.422@93.99 (lifted off and coasted through). The next pass I tried to realese the clutch a bit harder in an effort to try and lock the clutch a bit sooner. This resulted in wheelspin, and I had to chop throttleand ease back into things. For a pass with bad wheelspin, I didn't think the pass was too bad. 1.967 60' / 12.270 @ 115.98. The last pass I got back intot the staging lanes before they closed them. There was quite a bit of downtime, so I got to really cool the car down. The air was getting cool, and I was hoping I might get one last "hail Mary" in. The run was clean, but when I picked up my timeslip it was not to be....

60' - 1.865
330 - 5.098
1/8 - 7.767
MPH - 92.79
1000 - 10.065
1/4 - 12.008
MPH - 116.04

ARGHHHHH!

Anyway, this was probably the last "cool" weather we will have access to until winter. I am getting married in two weeks, follwed by a 2 week honeymoon. So, I will not be drag racing the car till at least some mid- July. But, at that that point it is so hot it will be pretty pointless.

Maybe between now and then I can get the clutch fixed and lay down some "real" numbers when the wether gets good.

One thing I am going to elaborate on in another thread that I thought was interesting was that I pulled the stock airbox cover off and left the stock filter exposed and gained 1-2 mph over leaving it on.