how much does da affect a trap speed?

well I took my pos ss to the track.my goal is to hit 120mph in the 1/4.its been that for a long time now over 2 years and still has not done it.
simple run down
116k miles on motor
tsp 5.3l heads stage 2.5
tsp 232/234 cam
slp longtubes o/r y pipe
loudmouth
ls6 intake
stock tb
9" 4.11

last week on the dyno it put down 403rwhp,raceweight on june 17th was 3,255

on june 17th I ran the car at the track in san antonio texas best mph was 12.7@115.03 at 9:28pm

so these are the facts 9:28pm trapped 115.03
San Antonio, Texas
june 17th
91*,dew/64,pressure/29.87,elevation 600

I plugged the #'s into the da thing that chrs1313 gave me and the da was 3081.....DA.3,081

then I plugged the #'s into the modular site da and it said uncorrected was 12.7 @115.03 and corrected was 12.2 @119.43


so does weather (da)make that much of a differnce?
115.03mph 3,081 da
119.43mph 0da

did I do it right?

I dont believe it makes that much of a difference.ill guess i will find out in the winter time when better weather comes around.

any others want to chime in

 

It absolutely makes that much of a difference. Once it cools down some, you may see some negative DAs, and thats when you'll break 120. My car, for example, ran 115.66 MPH back in January with a -900 or so DA. Now in the summertime when the DA is more like 2500, I only trap 112.11 or so. It makes a huge difference man.

 

What about your power numbers? Have you not thought 403 was a little low for a H/C car? What is your compression?

Maybe it's the cam, it may not be the right cam for that set of heads??

 

yeah 403 is kinda low for a h/c car

 

Absolutely DA makes a diff. You say magic air to some NJ guys and they go bullshit but there have been plenty of examples of cars doing Personal Best in colder, denser air that is directly related to DA.

The only issue you run into when its persay a track day and there is not enough heat in the track and cars with less then optimal suspension and tire combos can be blowing off their tires too. There is a fine line esp when big power comes into the picture.

Edit:

Here is a search string for a Member is the Eastern Members section that shows he was in the 12's and as the weather got better, he got faster. Look through what he posted and you will see the info. He is a classic example of car that if it goes to the track, during warmer weather, will not post a new PB if everything else stays the same.

https://ls1tech.com/forums/search.php?searchid=8022673

 

I use a weather computer to help dial in my car at bracket races. My LS1 is the most susceptible to weather changes of any car I have owned. I can easily see .5 difference running the same track.

Cars are more susceptible to weather changes at lower RPM so if you have an A4 a high stall converter will make it more consistent.

 

As mentioned above, DA can make a big difference. I usually see 3-4 tenths and 4-5 mph difference between the winter sea level or negative DA and the 2500-3000 DA in the Florida summers. Keep in mind a calculator is giving a time based on a correction factor, but every car will react to cooler weather differently (just like a bolt-on to one combination might affect it differently versus another).

Derek

 

I know it made a difference but I didnt think it would make 4mph difference.

hell yeah I think 403 rwhp is low for a heads/cam car.when the h/c was put on bout 12k miles ago.it put down 419 hp.so I put new injectors on svo 30lbs got a retune around 3 weeks ago and it did 403rwhp.tuner said it was cause it was hot out,wich it was in the 90's.

I think a good runnin tsp 232/234,tsp 5.3l stg 2.5,ls6 intake would make....435-445hp
435-445 then a 9" takes away power so 420-430rwhp

 

quick update got a retune with my home ported fast and tb and the car put down 441rwhp std,same tuner,same dyno,96*, 37%humid.almost same weather with cutout open.
made 3 passes
1.missed 3rd coasted the 1/4
2. short shifted 1-2 at 5k,then bounced 3-4 shift went 115.71
3.new best of 117.46,still shift slow cause car feels real stiff in the upper rpm's

117.46 in 3,191

next track visit will be with skinnies,liteweight battery,dumped.should lose about 70lbs and pick up a mph

 

with a da of 1339 my car went 11.30 at 119 da of 1768 car ran 11.5 @ 117.8 . with the mufflers off and da of 1114 it ran 10.99 @ 122 . Weather is killer sometimes .

 

Car still doesn't sound right to me for a ported head, big cam, light weight car 3250lbs with you in it. What rpm are you shifting at? My car has a 224 cam with non ported 243 heads and with me in the car it weighs around 3700lbs. In 3800 DA I ran 12.8 @ 115 mph with a 2.23 60'. I also run the stock 10 bolt with 3.42's. I would hope a car with ported heads, a bigger cam and almost 500 lbs lighter than me would mph much higher and with better DA. Something doesn't seem right.

 

read #3 in my last post,on the 1/2 shift I shift it around 5k-5.5k cause if i go higher it gets real stiff like im hitting a brick wall,all other gears i shift around,idk cause my stock tach stops around 6400,so I would guess 6600,I need to get a vid so yall can hear, how long it takes to get it into the next gear,I need to buy a tick adj master.

it does upset me when my bolton only car traps a 115 and a best of 116

you have a strong car nice job

 

If it takes a lot of time between shifts you will be down on mph that is for sure! Also a 1-2 shift around 5000 is really going to hurt you. Get a shift light in that thing and set it around 6600 and get the clutch issues figured out. When it cools down you will hit 120 no problem. 120 is also my goal but our track is 2,200' so I dont know if it will happen. The DA rarely goes below 2000. Also I welded in a $30 summit manual cutout and when I open that up at the track I gain 1.5mph! Not bad for $30. You should also look into building a ram air like the fast toys. I have not tested mine yet but I am hoping to gain 2mph with it.