How Much Does Density Altitude Affect ET

davidhuff · 12-12-2019, 04:23 PM

I know very little about Density Altitude and was searching for information.

Dustin Ward · 12-12-2019, 05:21 PM

Give this a read. Your results may vary.

https://www.biondoracing.com/tips.shtml

Dave Noll · 12-12-2019, 05:45 PM

My understanding that 1 and 2 barrels swing wider than 4 barrels and low compression wider than high compression and a stock converter (sportsman bracket) wider than a high flash converter, etc, etc, etc, etc . The really good cars may change very little with the weather.

jmcarter · 12-12-2019, 06:19 PM

While I’ve always referenced Biondo’s tips as a guide I would just point out that meticulously keeping notes on all your runs is invaluable to setting up a reliable correlation curve between DA and ET since the host of other variables (i.e. wind) can play such a huge role. I’m just now trying to explore some of the analytics of this and discover that my last year’s record keeping was painfully inadequate. You can probably guess one of my New Year’s resolutions.

Ralph A Powell · 12-12-2019, 08:24 PM

Percent of oxygen changes can have a big impact and since very few measure this the basic numbers can remain the same but the percentage of oxygen can change and have a large impact!

Keith 944 · 12-12-2019, 08:32 PM

On my two cars basically 200 feet of altitude change equals one hundred .01 I run them a little fat so that it will be this way

Dave Muller · 12-13-2019, 11:21 AM

Quote:

Originally Posted by Ralph A Powell

Percent of oxygen changes can have a big impact and since very few measure this the basic numbers can remain the same but the percentage of oxygen can change and have a large impact!

I've been strongly suspecting for a while that this is the case. When I stay near home I can get a pretty good idea from DA and wind but then I go to a different area, where they have those weird tall things (I think they call them trees) and suddenly I'm way off in my dial-in.

340Cuda · 12-13-2019, 11:24 AM

Quote:

Originally Posted by Ralph A Powell

Percent of oxygen changes can have a big impact and since very few measure this the basic numbers can remain the same but the percentage of oxygen can change and have a large impact!

So at the same DA the percent of oxygen can be different?

How do you measure the percent of oxygen?

Thanks

Pete Lanciers · 12-13-2019, 06:07 PM

Quote:

Originally Posted by jmcarter

You can probably guess one of my New Year’s resolutions.

Right there with you Jimbo, I just recently came to the same conclusion!

12-12-2019, 04:23 PM	#1
davidhuff Senior Member Join Date: Jul 2009 Posts: 928 Likes: 1 Liked 120 Times in 42 Posts	How Much Does Density Altitude Affect ET I know very little about Density Altitude and was searching for information.

12-12-2019, 05:21 PM	#2
Dustin Ward Junior Member Join Date: Feb 2009 Location: Renton Washington Posts: 35 Likes: 27 Liked 4 Times in 2 Posts	Re: How Much Does Density Altitude Affect ET Give this a read. Your results may vary. https://www.biondoracing.com/tips.shtml

12-12-2019, 05:45 PM	#3
Dave Noll Senior Member Join Date: Nov 2007 Location: Div. 6, Eastern, WA Posts: 709 Likes: 2,668 Liked 238 Times in 111 Posts	Re: How Much Does Density Altitude Affect ET My understanding that 1 and 2 barrels swing wider than 4 barrels and low compression wider than high compression and a stock converter (sportsman bracket) wider than a high flash converter, etc, etc, etc, etc . The really good cars may change very little with the weather. __________________ Dave Noll, EF/S ,?/SA 6526 Last edited by Dave Noll; 12-12-2019 at 05:47 PM.

12-12-2019, 06:19 PM	#4
jmcarter VIP Member Join Date: Dec 2008 Location: Richmond Hill GA (and Port Ludlow WA) Posts: 4,295 Likes: 2,378 Liked 3,174 Times in 971 Posts	Re: How Much Does Density Altitude Affect ET While I’ve always referenced Biondo’s tips as a guide I would just point out that meticulously keeping notes on all your runs is invaluable to setting up a reliable correlation curve between DA and ET since the host of other variables (i.e. wind) can play such a huge role. I’m just now trying to explore some of the analytics of this and discover that my last year’s record keeping was painfully inadequate. You can probably guess one of my New Year’s resolutions. __________________ Jim Carter 2340 Super Stock 2340 SST/2340 Stock Set another place at the table

12-12-2019, 08:24 PM	#5
Ralph A Powell Member Join Date: Oct 2017 Location: Bay City Texas Posts: 388 Likes: 2 Liked 225 Times in 136 Posts	Re: How Much Does Density Altitude Affect ET Percent of oxygen changes can have a big impact and since very few measure this the basic numbers can remain the same but the percentage of oxygen can change and have a large impact!

12-12-2019, 08:32 PM	#6
Keith 944 VIP Member Join Date: Feb 2006 Location: Dela-where? Posts: 2,193 Likes: 1,160 Liked 1,877 Times in 577 Posts	Re: How Much Does Density Altitude Affect ET On my two cars basically 200 feet of altitude change equals one hundred .01 I run them a little fat so that it will be this way __________________ KEITH MAYERS 2-1/2 X somebody Still many X nobody

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