got a simple question with a vehicle with big block chevy and a 1050 gas carburetor how much should a vehicle change in 86* and 79% humidity to 64* and 41% humidity i know everybody stuff is different just trying to get a ballpark before I start changing things. Thanks

quote:

Originally posted by MGeorge:
got a simple question with a vehicle with big block chevy and a 1050 gas carburetor how much should a vehicle change in 86* and 79% humidity to 64* and 41% humidity i know everybody stuff is different just trying to get a ballpark before I start changing things. Thanks

This will work, for very broad strokes. But be forewarned, the barometric pressure is every bit (if not more) of a factor than the other two. You could input the same pressure for both calculations, but it RARELY works out that way in real life.

wallace racing calculator

Take care. Tom Worthington

2 tenths difference in the 1/8 would not be out of the question. That is a massive difference in actual water content and a HP Correction Factor difference of .06-.08 depending on barometer.

There is a lot of things to consider here. First off you need to use same gages. I have seen variation of 1000 Feet Density Altitude on two different gages. Does not matter as long as you use same ones for your records. A good weather station with prediction is worth it and will pay for itself quickly.
Keep good records. Best days to test are really good air and really bad air then you can start making a chart and doing math what it would run in between.

You did not mention Barometric pressure and that is a huge factor in performance. I usually rely most on Density Altitude which takes into account several variables including Temps, humidity and barometric pressure. Wind effects ET but not as much as Barometric Pressure or DA and less of a factor in 1/8 mile.

At first I recorded most all weather variables. (I still do) but now after years of doing it I have learned which ones effect my car more. When you record all the information you start looking for things that stand out. Car picked up more than you expected? What changed on the weather? Unless you have a mechanical issue your cars performance should be effected by weather in a repeatable way. Sounds easy but it is not, one car will change more than others in same weather. Wind effects less aerodynamic cars more. Right now I am setting up a few cars and they are totally different than my previous cars so I am having to get a new baseline.

In you example above ASSUMING Barometric Pressure was same yes car would run slower at 86* and 79% humidity.

.27 difference between the best air of the season and the worst on my gasoline setup.

I thought something was wrong with my slow dragster because it fell off exactly 2 tenths. and it was the racetracks system that they print on the tickets. Thanks for the responses!

Every bit of .10-.15 difference on gas.
Only .05 difference on Alky

.0025 to .003 sec per 100’ density altitude change. 3,000’ da diff between summer and winter da here in NC equals around .090 et change for summer to winter for my car. Around a tenth….

The number one thing I have found to reduce changes due to weather is a converter that is a tad looser than what the fastest converter would be in your best air.

Thanks Bucky I was thinking about doing a converter swap just to try something because I think I am a lot tight

[QUOTE]Originally posted by MGeorge:
Thanks Bucky I was thinking about doing a converter swap just to try something because I think I am a lot tight[/QUOTE

Yes a lot tight will be much less consistent.

quote:

Originally posted by Bucky:
[QUOTE]Originally posted by MGeorge:
Thanks Bucky I was thinking about doing a converter swap just to try something because I think I am a lot tight[/QUOTE

Yes a lot tight will be much less consistent.

What does the OP consider being a lot tight?

2BKING

still, talking converter?

This message has been edited. Last edited by: wideopen231,

quote:

Originally posted by B KING:

quote:

Originally posted by Bucky:
[QUOTE]Originally posted by MGeorge:
Thanks Bucky I was thinking about doing a converter swap just to try something because I think I am a lot tight[/QUOTE

Yes a lot tight will be much less consistent.

What does the OP consider being a lot tight?

2BKING

If it is tight for most, it's probably way too tight for me.
Err....yes tachs.

if i can get some help from the wife i will post a video i made of the tach if you guys will read for me

33/16.5x15 slicks with a 489 gear. It had a 410 gear in it, changed it to the 489 but I haven't seen any difference yet after 25 runs. this is my run with this new set up.

https://youtube.com/shorts/Ysg...?feature=share

This message has been edited. Last edited by: MGeorge,

did anyone look at video and can give me any advice?

quote:

Originally posted by MGeorge:
did anyone look at video and can give me any advice?

I really can't give much from that video.
Do you have any other capabilities in the car of gathering data?

quote:

Originally posted by MGeorge:
did anyone look at video and can give me any advice?

The fact that 10 days have past without a reply should tell you that video shows us/tells us nothing and what advice exactly are you looking for?

Don’t mind Edna. Nobody likes him and he’s taking it out on the new guy. Did my take it personally

thanks no other means to record data not a high end build