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View Full Version : 60 ft vs Air charge temps?



sizemoremk
10-23-2005, 03:44 AM
Hey guys, got a last minute invite to go to the local 1/8th mile track and got some numbers to cipher...

I am wondering if temps after heat soak should affect 60ft times???

First off, I set a record! 8 passes in a 20 minute span :D

Little background, 50 degrees, track was sticky, I guess thay had lots of track bite or something!!! Hardly any cars showed for the "midnigt maddness" which is what they call our "open track"... So all of the runs were no wait at all:eek: It was dead!


We get there and I let her sit for about 45 minutes, and had a no wait run of:

1.8958 60ft
9.5052 ET
71,82 MPH

Then another of

2.1233 60ft
9.5651 ET
73.24 MPH

Both were regular AOD shifted, w/o holding the brake and gas to heat up the converter. No burnout, no reduced tire pressre, just spining them a little to get the grit off. And the folks I was with said they never noticed me spinning off the line, they actually commented on hearing the tackiness of the tires...


Then let her cool off about a half hour and made another 8 passes in 20 minutes. Driving straight and not having to wait at all.

I tried everyhting from reving to about 1500RPM on the launch, to the AOD shuffle, trying to lower the ET, but I never could approach the 60ft of 1.89 again and got slower :confused:

My other 60ft times were between 2.025 and 2.273 with ETs between 9.66 9.75. Most in the 9.7 range...

Now, I datalog my ACTs, however I haven't actualy calibrated the PLX "digital dash" voltage with the sensor voltage, so it could be off, but the indication now is that the max temp was 160ish on the last couple of runs. I also changed the knock detect retard from -8 to -4 degrees since I've about go the new motor ready, and I was feeling adventurous :)

I feel that the reason for the slower runs was the 60ft times, but that doesn't necessarily explain the small .060 ET difference with 0.2275 differences in the 60ft times of the first two runs???

Maye these cars are more sensitive to ACTs than I thought? I would have thought on a sub 50 degree night, with no wait in the staging lanes, that the heat soak would have been minimal...

I suspected that the ETs would have been affected by the raised ACTs, but I didn't think that the 60ft times would have been effected that much?

Do I just have launch issues due to little to no expirience in drag racing, or did the temps cause this???

The current state of mods by the way is still kinda low; I have a MAC CAI, 10%, raised top, double IC (IC fan is currently removed), and exhaust.
All the other stuff is still in the garage :o
And oh, the 4R70W gearset...

The highlight was the last coupla run, where I pulled a late model blown Grand Prix twice :D

So what are your opinions???

David Neibert
10-23-2005, 08:26 AM
No matter how many mods you have or what the outside temp is, these cars will always run slower if hot lapped. They need to cool down between passes, that's why many of us use a couple bags of ice at the track.

I don't know if it's heatsoak or ACTs or a leaner fuel mixture, but thet will always get slower if not allowed to cool. More so if your running a 1/4 mile track.

David

92strokedbird
10-23-2005, 08:44 AM
It would have helped to have a fan to cool the ic.I would have imagined not much time at any sort of speed to get the air thru it.

90blkbrd
10-23-2005, 09:19 AM
The only time I have been to the track...I had 3 back to back runs, they wanted to close early so we rushed the races (club clash VIII in Iowa). All three time slips were almost the same. 8 passes in 2:20 and all of the inconsistances were all in the driver and not the car.

You didn't state what your traction was like in the later runs, did it get colder and the tires weren't hooking up?

83GT460
10-23-2005, 09:52 AM
Your car will definately slow down if you hot lap it, but I don't think that is the issue here. I would say that something went wrong with the timing system at the track because if you car has enough power to run that quick of a 60 ft time it would be much quicker in the 1/8 mile.

92strokedbird
10-23-2005, 09:54 AM
It appears that he had no traction problems as he had an audience and they stated that he was not spinning and had good traction.Once the ic gets heat soaked it takes a lot of air flow thru the cores to cool them down and driving back to back runs would certainly get it heat soaked especially without a fan on the ic.

Jeremy_K
10-23-2005, 10:01 AM
1.8 is a pretty impressive 60ft for street tires. I have an IC fan and still run consistently slower times if I keep doing laps. My last 2 times to a track,(once here in NM and once in OKC) I ran my best times on my very first run after letting the car ice down for an hour or so. After that I just got worse.

fastsc92
10-23-2005, 10:31 AM
Here is my comment just from experience. Yes, you're times will slow down if hot lapped, however I feel this has little or no effect on your 60' time. Even if you hot lap, the IC should have enough time to cool down to the 120 range, which is still horible, but better than 160. When i was running my stock IC, fan and raised top, I was seeing a max of 160 as well, and a starting temp of 120. It would cool down to around 90, but once i started my burnout, it was jump right up to 118-120. The new IC never see's temps 15 deg above outside air.

Anyhow, I'm not too familar with 1/8th mile tracks cause a lot of things can change once you reach mid track. For example, my car would haul the first half, and then it would slow down. A poor exhaust, and IC were to blame and the just couldn't keep up in the higher RPM range..

A 1.8-1.9 isn't bad for street tires, but you cant expect anything better than that.

Its hard to explain exactly what happens, but when I raced on street tires, and If i spun really bad, I'd get a low et and a fast MPH. A slower 60' will do the same. IMO everything is in the launch, and you cant expect too much more with the tire and suspension set-up you're running. Hot lapping does have an effect in overall performace, but I doubt it effects the 60' times.

As far as the tuning, there is really no need to touch that knock retard. Its there for safety and changing it wont produce any power. If you are knocking, its there for a reason, and there are other issues you need to address. If anything, change your ACT WOT advance, but even still, you dont want to be running high timing at 160 degrees.

My final comment is to invest in a set of drag tires. I would go out and spend the money on some ET streets, or QTP's. I think the QTP's fit better on a stock size rims since they are 9.5" wide. I've been running those in my 5 speed and from a 3k drop I pull consistant 1.6-1.7's. It was well worth every penny, and I know you wont regret it. Why spend all the money on mods if you cant hook up??

anyways, a 9.5 1/8 mile converts to about a 14.82 1/4 mile.

CMac89
10-23-2005, 11:22 AM
I agree with the ACT's not affecting the 60ft. times. 60ft. is more of a number you use to manipulate the traction you had.

ACT's will greatly affect your E.T. You should never make a run until everything is cool again including your blower, IC, etc... If that means only making 3 to 4 runs then so be it.

Jeremy_K
10-23-2005, 12:01 PM
There's still nothing wrong with making multiple runs. The more you practice, the better you'll be launching. Sometimes when I go to the strip, I'll run many times consecutive because my 60ft. times really need some work. Other times I'll go there and run once an hour after icing down.

sizemoremk
10-23-2005, 02:36 PM
As far as the tuning, there is really no need to touch that knock retard. Its there for safety and changing it wont produce any power. If you are knocking, its there for a reason, and there are other issues you need to address. If anything, change your ACT WOT advance, but even still, you dont want to be running high timing at 160 degrees.

My final comment is to invest in a set of drag tires. I would go out and spend the money on some ET streets, or QTP's. I think the QTP's fit better on a stock size rims since they are 9.5" wide. I've been running those in my 5 speed and from a 3k drop I pull consistant 1.6-1.7's. It was well worth every penny, and I know you wont regret it. Why spend all the money on mods if you cant hook up??


Roger that, I was kinda more curious if I was knocking, and figured this would be the way to find out. I am not aware that my car has ever had any knock...

Now the tires, there is a "tire plan". Thats all I can say about it at this juncture :cool: