[PRAY]

So there has been a ton of discussion about my last passes with many attributing it to the weather. I am going to post up what the car has ran in the past, what the weather and DA were at the time, what the mods at the time were and the logs. I think in the end it will show out that the DA really hasn't had much to do with things at a certain point. The DA I am going to post will be from my Kestrel device since that data was taken at the track at the times of the runs.

I am trying to spark some discussion on the subject and get other people with a lot of track experiences opinions. All I can do is post what I have done and go off of that. I will first post my best ET's/MPH's for the 1/8th and 1/4. They will be an accumulation of the bests so they won't exactly match my time slips. We can talk averages later if need be. Then some common "knowledge" of how weather effects those times and finally my logged data. My logged data will consist of Spark, IAT, G/CYL, MAP, MAF data. I could post AFR as well but that doesn't really matter. That will be chalked up to tuning. I tuned for each day individually.

Bone Stock, DA +1,900, 393/413rw:
60ft 1.88, 1/8 8.00@90.95, 1/4 12.33@114.68

Ported IM/TB/Tune, DA +900, 418/433rw:
60ft 1.81, 1/8 7.67@93.52, 1/4 11.87@116.55

Ported IM/TB/Tune/RF, DA +1,300, 440/460rw: almost a throw away day due to wheel spin.
60ft 1.85, 1/8 7.83@92.18, 1/4 12.06@116.88

Ported IM/TB/Tune/RF, DA 0, 440/460rw:
60ft 1.77, 1/8 7.57@94.68, 1/4 11.73@117.31

Ported IM/TB/Tune/RF, DA +200, 440/460rw:
60ft 1.80, 1/8 7.56@95.06, 1/4 11.70@118.02

Ported IM/TB/Tune/RF/E85/Drag Pack, DA -900, ?/?:
60ft 1.57, 1/8 7.09@99.10, 1/4 11.07@123.02

Now for racer math. Lets assume the E85 was worth 30rw. That is a safe low bet based off of everyone elses numbers and my logs. The drag pack took roughly 90lbs off the car and 26lbs off the rear for rotating mass. Fuel level stays about the same for all my testing. The 60ft was .2 better and the weather was 900ft better. Who knows what being able to smash the gas off the line and keeping traction all the way down the track is worth.

E85 -.3 tenths
60ft -.4 tenths in the 1/4
Drag Pack -.1 for weight and probably -.05 for rotating mass
DA -.1 tenth

E85 +3mph
60ft +2mph for being able to go WOT and have it hold
Drag pack +1mph for weight, +.5 for rotating mass
DA +1mph

So total I am looking at a .85 gain not accounting for weather. Add in the weather and I should have gone a second faster than my last time out roughly. My last time out on the street tires, had the car not spun the shifts, I would have been in the 11.6 range easy. That was easing it off the line due to the street tires. Then plus 7mph for the same stuff.

I only gained .5 in the 1/8th and .7 in the 1/4 and 4mph in the 1/8 and 5mph in the 1/4. So where is all of this weather benefit coming in?

[parish8]

I love the calculators at Wallace racing. I did a da drop of 1100' on your 11.70/118 run and the et dropped less than .1 and mph went up less than 1.

I think you are right that your gains were mostly other things than da drop. Doing the same math on your stock run and a 2700' drop shaves .26 off.

http://www.wallaceracing.com/da-et.php


any idea what drag radials only on an otherwise stock car do for us?

[PRAY]

Originally Posted by parish8

I love the calculators at Wallace racing. I did a da drop of 1100' on your 11.70/118 run and the et dropped less than .1 and mph went up less than 1.

I think you are right that your gains were mostly other things than da drop. Doing the same math on your stock run and a 2700' drop shaves .26 off.

http://www.wallaceracing.com/da-et.php

I love Wallace too. You can plug it into Drag Times as well. I am not even sure if the NHRA site corrects below 0.

I don't have time for all the log data right now but when I looked over it all this morning there really wasn't all that big of a difference in IAT between all the runs since the 11.7's. So what the motor was seeing wasn't that big of a change. ECT is pretty much identical. G/CYL is up but it has been up on the E. A 1* bump in timing also shows a corresponding bump in g/cyl in back to back runs. But a 1* bump shows just about nothing on the dyno when you are at or beyond MBT. I think the largest delta on g/cyl is .4 or .5. It has been up an average of .3 on E when comparing identical weather logs. I can't account for baro yet. I will also mention that my MAP is up quite a bit but I think that is due to me actually cleaning my filter. It makes no since that a motor making more power with the same intake track won't show more of a restriction. I can't see weather effecting my MAP readings but I haven't delved that deep into the MAP sensor stuff yet. I do think that a 1-2 KPA bump in same weather is worth around 10rw though.

The more I look into the actual data this stupid car should have gone 10.7's according to accepted "science".

[Snowblind]

I would have to dig up a crapload of slips to get scientific about my exact times, but in my case I noted that it worked out to about a tenth for every 500 DA difference ( on 93 gas). I do believe e85 is less effected by the DA swings throughout the year. The best air I had was -800 so I don't know at what point your gains increase beyond that.

Edit; I actually have a thread started on this...DA and it's effects on my car right here in the drag section

Originally Posted by parish8

any idea what drag radials only on an otherwise stock car do for us?

I got one pass 100% stock except DR's and went 11.94 on my only pass that day. Full weight and my M/T set up weighs more than the stockers. (1.80 60' and 500 miles on the odom, I wish I could have made more passes...my first pass has always been my slowest)

Side note; I plugged in PRAYs data into Wallace yesterday and came up with 550+ hp at the crank....seemed a tad high but i use that calculator a lot also.

[parish8]

Originally Posted by PRAY

The more I look into the actual data this stupid car should have gone 10.7's according to accepted "science".

Where do you get that number? If you punch in 500hp and 3850 you get 11.5. You are well ahead of what the calc says.

[PRAY]

I think the only real comparison to make here is what my last passes were in 0 DA on the street tires and pump to now on the E85 and drag pack. If we do that then I should have gone way faster. If it doesn't rain Sunday and the track is open I will go back on pump and see what happens. It is supposed to be in the high 70's and humid.

The only real variable now is finding out what is scrubbing my speed in this rear or trans.

If every 500 ft of DA was worth a 10th this thing would be flat flying.

[PRAY]

Originally Posted by parish8

Where do you get that number? If you punch in 500hp and 3850 you get 11.5. You are well ahead of what the calc says.

I was adding up all the subtraction and applying to my pre E/Drag Pack times.

[BadBowtieProductions]

Your car runs good for what's done to it, no matter how it got there. It would be nice to see your car make zero changes and go run again in some 2000+ DA, just to see what happens...but making that happen isn't worth the trouble.

I can say for certain mine went faster because of the air. I made an easy an easy 30+ passes this year 100% stock. I tried a few different launch techniques every time I went, no matter the DA, just so there was a control. These are just the few I remember offhand (PB each night), DA is probably within ~100 on all, just can't remember the exact numbers since I don't have my slips at work.

2000 DA - 12.20 (a week after I bought it)
1300 DA - 12.12
1200 DA - 12.13
500 DA - 12.07
-100 DA - 12.04
-300 DA - 11.99 (tires beyond the wearbars)

I hit a brick wall in summer, and could not get any faster. I had could get 1.79-1.82 60's consistently with certain launch procedures, but still, no big drop.My best 60' ever was 1.78, and it didn't net me my best time. My 11.99 was on a 1.83 60'. Once the DA started falling at the end of the year, so did my times. These are all same gas level, same (stock) tires.

The air DOES make a difference; how much is really just a question that is tough to say unless you do testing with the same set up, with only the weather changing. It was worth about 2 tenths to me, which seems just about right.

[Padre]

Back in the day (before I supercharged my Gen5), I did each mod incrementally, did passes at the track, and logged everything.

http://www.camaro5.com/forums/showpo...01&postcount=2

Of course, changing DA meant actual track times with different mods on different days would be difficult to track.

But, I approached it from the perspective of the dyno: a dyno is just a tool, best used to measure deltas (changes). At the track, I used the standard calculators (Wallace or Drag Times) and applied it uniformly, good or bad. (For example, when I added the CAI in -769 DA, I ran a 12.761, but corrected it was 12.85.)

Key thing that gave me was the delta I needed to see if the mod was worthwhile. While the actual numbers were interesting, the most important information was the delta.



I even did a cost/mod calculator:



So, my recommendation is just be scientific about it rather than focus on numbers. Correcting for DA and comparing will give you very useful information.

Padre

[PRAY]

Here is the other giant issue. Were the above cars on stock tunes? DA makes a monumental difference on stock tune cars. Mine picked up 12/20 ish two weeks apart stock. No tuning adjustments.

[PRAY]

Originally Posted by BadBowtieProductions

Your car runs good for what's done to it, no matter how it got there. It would be nice to see your car make zero changes and go run again in some 2000+ DA, just to see what happens...but making that happen isn't worth the trouble.

I can say for certain mine went faster because of the air. I made an easy an easy 30+ passes this year 100% stock. I tried a few different launch techniques every time I went, no matter the DA, just so there was a control. These are just the few I remember offhand (PB each night), DA is probably within ~100 on all, just can't remember the exact numbers since I don't have my slips at work.

2000 DA - 12.20 (a week after I bought it)
1300 DA - 12.12
1200 DA - 12.13
500 DA - 12.07
-100 DA - 12.04
-300 DA - 11.99 (tires beyond the wearbars)

I hit a brick wall in summer, and could not get any faster. I had could get 1.79-1.82 60's consistently with certain launch procedures, but still, no big drop.My best 60' ever was 1.78, and it didn't net me my best time. My 11.99 was on a 1.83 60'. Once the DA started falling at the end of the year, so did my times. These are all same gas level, same (stock) tires.

The air DOES make a difference; how much is really just a question that is tough to say unless you do testing with the same set up, with only the weather changing. It was worth about 2 tenths to me, which seems just about right.

I agree DA makes a difference. With out a doubr. But where is the deminishing return when it comes to cold?

[PRAY]

By the way guys, this is phenomenal information and descussion. Thanks.

[Padre]

Originally Posted by PRAY

I agree DA makes a difference. With out a doubr. But where is the deminishing return when it comes to cold?

Realistically, dew point. I've been at the track on great nights, but once the dew point gets too high, the track turns to ice.

Padre

[BadBowtieProductions]

Originally Posted by PRAY

I agree DA makes a difference. With out a doubr. But where is the deminishing return when it comes to cold?

I'm not sure where the gains would begin to diminish, but I think track surface temperature comes into play when you get deep into negative DA. I'm just glad I have ran in all kinds of air so I can compare anything to it this coming year. I plan on having some similar mods as you by the time the track opens, so we'll see how it goes.