Test and Tune ATL Dragway Results

driller

driller

El Presidente
Staff member
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The list of changes I made from last year, to this year, are as follows. Both times, all filters are new:From stock height to sensor lowered 22 1/2"
Replace Conti rims/Symmetry tires with OctaStar rims/RE750's
Replace APP103's .048 (one step colder) with 764's .054 (stock)
From silencer delete to home made CAI mod.[/div]

Glad to see someone driving at the track!!!

FWIW, I'd gamble the OctaStar/RE750 combo as significantly heavier than the Conti rims/Symmetry tires?

Lowering should only make the car more aerodynamic, but i do wonder about the effect of weight transfer on the launch.

I'm not so sure anyone has ever proven a gain at the track due to spark plugs? So conversely, if the plugs are in good shape, I highly doubt they contributed to any slowness. Same on the CAI?
 
RE: Test and Tune ATL Dragway Results

I don't know, but I would think with the IMRCs not working, you would've been much, much slower. I know the Gen1 IMRCs are vacuum controlled vs. the Gen2 electric actuator.

I've never done it, but if you could disable the IMRCs and then test the car, I'd say you should see a dramatic difference. On the Gen1, that should be as simple as unplugging the harness at a vacuum solenoid. I have no clue on the Gen2 setup. Wouldn't the OBDII throw a code with malfunctioning IMRCs?

In my limited experience, I see a huge disparity trying to compare track runs of different dates even at the same track without correcting for density altitude. Temperature and humidity needn't be a lot dis-similar to make a significant difference in density altitude and subsequently the HP gain/loss. Even once corrected for density altitude, the standard deviation from other factors can make it difficult to point a finger at any particular item responsible for less or more performance - unless that element causes quite a substantial difference in HP or vehicle performance. Subtle changes require a trend analysis over many track runs, not just simply an A/B comparison.
 
RE: Test and Tune ATL Dragway Results

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Does weather have that much factor? I thought maybe a 10th, and 1 mph, but a half second and 3-4 mph? Seems like alot to me.
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Let's examine...

86 degrees F @ 30.00 inches Hg and 40% humidity equals a density altitude of 1865 feet and a HP correction factor of 100.1%. Modestly increase the temp 10 degrees and the humidity 10%... 96 degrees F @ 30.00 inches Hg and 50% humidity. Density altitude is now 2628 feet and relative HP is down to 97.6% - a 2.5% drop in HP.

http://wahiduddin.net/calc/calc_hp_abs.htm

Do the math. ;) In my experience I have seen 0.4 to 0.5 seconds and 3-4 mph attributed to weather conditions.
 
RE: Test and Tune ATL Dragway Results

Rainman. Hurricane forecaster... LOL

Hobby? I can't have a hobby without it turning obsessive compulsive. I was trying to make a point that a difference of only 10 degrees and 10% humidity is equivalent to a 2.5% loss of HP, in my case that would be approx. 6.3 RWHP - definitely enough to make a measureable difference in performance. Further weather variation could prove even more dramatic.

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...What does concern me, if you look across the 1/8 mile mark, and mph, how I lost 3mph and .3 tenths in three hours. Again, is that normal within that short period of time?
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Short answer... heat soak. I have documented about 1.5 mph and 0.2 tenths ET drop in the 1/4 mile solely attributed to heat soak - and I have a cooling system over-ride that minimizes it as much as practical.

http://www.lincolnsclub.org/forum/user_files/976.jpg
 
RE: Test and Tune ATL Dragway Results

I'm impressed the OctaStars are actually slightly lighter. I'd still like to get my hands on a set of light weight wheels and some Mickey Tompson ET Street Radials! }(

Yes, the almanac shows it was definitely more favorable conditions last year at the track for you. Actual track temperatures will always be higher than weather records indicate. On a bright midsummer day, I 've found actual track temps can soar 20 degrees hotter than the 'official' temperature. On the average, it will be about 10 degrees warmer on a sunny day.

I verified my outside air temperature readings with a digital temperature gun and had the sensor relocated to the CAI behind the fender. I use it to record actual temperatures at the track. I then use the wunderground.com site for humidity and barometric readings. I suppose I could get a portable weather station to take to the track. ;)
 
RE: Test and Tune ATL Dragway Results

That MPH is awfully low, especially for an LSC. You should be above 94mph. Looking at your runs 90-91.x you're lacking serious power.
 
RE: Test and Tune ATL Dragway Results

Using: http://www.modulardepot.com/density.php

Based on:
Temp: 73.4°
Humidity: 53%
Track Altitude: 1100 feet
Pressure: 30.12 in.

Density Altitude = 2251 feet ET MPH
Uncorrected 15.39 @ 91.78
Corrected 15.00 @ 94.12

Taking the weather info for last year which looks like about 15 degrees difference in temperature from this year, and the average humidity and barometric pressure...

Based on:
Temp: 58.4°
Humidity: 51%
Track Altitude: 1100 feet
Pressure: 30.14 in.


Density Altitude = 1181 feet ET MPH
Uncorrected 15.019 @ 94.09
Corrected 14.83 @ 95.28

That leaves a corrected difference of 0.17 ET and 1.16 mph trap speed...

Well within reasonable statistical standard deviation(even for a LSC). ;)
 
RE: Test and Tune ATL Dragway Results

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Do you think the CAI and stock heat range plugs are the 0.17 ET and 1.16 MPH delta? Secondly, are you saying I ran a 14.8 if I was at sea level last year?
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Yippie! :D

Many factors could contribute 0.17 ET / 1.16 mph. Traction and the launch are critical to the 60 foot numbers which are a pre-cursor to the ET and trap speed. Wind factors in at times. Tire pressure and contact patch are another. There are countless others.

Corrected values are good for comparing the effects of mods. Even then, it is the trend you watch for. Not so much the individual numbers.

http://mark8.org/users/driller/pics/racing/8thmileET.jpg

That's a chart from track runs last year.
 
RE: Test and Tune ATL Dragway Results

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Do you think the M/T tires and lightweight rims will get you down to a 1.7-8 60'? Or, does it get more difficult to squeeze another tenth or two without serious mods?
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I can tell you it certainly does get more difficult to squeeze another tenth or two with each performance mod, IMHO. That is why a lot of people go for the big bang items first. The problem is then to make sure you have the proper supporting mods along with it. My approach has been to squeeze every ounce of naturally aspirated performance before contemplating any big ticket power adders such as nitrous or a supercharger. Upgrades are made not only with initial performance impact in mind but also to form a foundation for any future mods I may do.

I've been told with the right tire/wheel/traction combination, my sixty foot times will be in the 1.8x range or perhaps lower? I barely eeked out a 1.9 last time out. My ET and MPH estimates have been pretty close to expectations, but I'm sure I'm 'leaving some on the table' in the sixty foot due to traction issues. Exactly how much, I don't know. It's one of those things you just have to work at and find the best cost effective solution.

I KNOW I need to upgrade the tires for a more effective launch. In doing so I will most likely need to change them at the track, so that means I will require spare wheels. If I need spare wheels, I may as well maximize the performance by selecting the lightest wheels to mount the better tires. Now looking ahead, keeping those tires firmly planted may require examining suspension issues, such as bushings, mounts and braces.

It's a vicious battle, but before I move onto the next step, I want to make sure I have done everything that needed to be done to extract maximum performance at the level I am.

Here's another 'trend line' from this year's runs at the track:

http://www.lincolnsclub.org/forum/user_files/977.jpg
 
RE: Test and Tune ATL Dragway Results

I started running at the track last April, but I already had a chip, exhaust and 4.10s.

The biggest bang of last year came in improving the sixty foot times with the Baumann shift kit and drag radials. They were worth about 2-3 tenths combined in the 1/4 mile. The big bang this year was the stall converter and SCT chip from Blue Oval Chips.
 
RE: Test and Tune ATL Dragway Results

I got quite an improvement out of my exhaust (3 tenths or better), but I have a base model and didn't have the true dual exhaust to start with.
 
RE: Test and Tune ATL Dragway Results

Cool! :)

Now you can hold your own at SSHS5?
 
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