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how does DA affect dyno numbers?

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Old 11-11-2006, 08:52 AM
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Default how does DA affect dyno numbers?

If a car dynoes at 450rwhp at DA of 3900, how would it fair at say 0 DA?
Old 11-11-2006, 02:31 PM
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I'll take a shot at this one.

Normal rule for DA is a 3% reduction for or every 1000 foot increase. Believe me, the calulations can get real tricky..different temperatures have different effects as the altitude increases etc..

I've used the "Engine Tuners Calculator" before..(Google) with pretty good success. Have had some hot summer days at Denver, Colorado where the DA was 9350. About a 22% loss of power.

If your orginal 450HP was uncorrected, then about 504HP.
Probably why most people like SAE corrections..evens the playing field.

Hope this helps..
Old 11-11-2006, 02:38 PM
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Thats why everyone posts SAe corrected numbers....

IT puts everyone on a almost even playing field
Old 11-12-2006, 07:52 AM
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Last time I was on the dyno...the correction factor was 1.17.
445 actual
531 SAE
Old 11-12-2006, 03:46 PM
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Originally Posted by nomorews6
If a car dynoes at 450rwhp at DA of 3900, how would it fair at say 0 DA?
You did not specify if that number is corrected power or uncorrected. If it is corrected and the weather instrumentation is set up correctly, then is should make the same corrected power at 0' DA.

Brian
HiTech Motorsport

Last edited by HTMtrSprt; 11-13-2006 at 09:58 AM.
Old 11-12-2006, 10:11 PM
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Read this as it sums it all up!

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

Howard
Old 11-13-2006, 08:42 AM
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Is the dyno correction factor a multiplier? Mine was .94 or .98 or something like that. Does that mean that my numbers were pulled down in the correction slightly as I am at sea level and the air was not as humid and hot as usual?
Old 11-13-2006, 08:53 AM
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If the correction factor is 1.00, then the dyno results are based upon standard measures. I believe its 29.92 pressure, 60 degree temps and 20 % humidity. If the number is less then 1.00, then the air better if it is higher the air is worse.

I most dyno's will compensate for this so if you dyno in the summer and go back in the winter the results can be comparable.

The DA is Density Altitude and indicated in feet. If the DA was 0 then standards at that sea level are absolute. When the air is bad the altitude goes up and vice versa. It is a measure typically used for aircraft as the DA effects the fueling of the engine as less air is available the higher you go.



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