I need to do some comparisions between my DA and
sea level for HP, any body got a compensation factor
based on SAE factors
Thanks

Probably not exactly what you're asking for, but try these links:
http://wahiduddin.net/calc/density_altitude.htm (use for converting temp, pressure (Hg”) and dew point into DA)

http://www.csgnetwork.com/relhumhpcalc.html (relative horsepower calculator)

Maybe some info here

http://www.wallaceracing.com/Calculators.htm

Not hp, but et and mph

http://www.smokemup.com/auto_math/nhra_correction_factors.php

Thanks for the links guys, I should be able to use them

Avaition uses actual altitude to figure percentages of power at the higher altitude, no links or reference materail avaible that I can link to or tell you the names of the books and authors, sorry. My old airplane, 1960 piper Comanche had a newer 260 hp Lycoming engine it that was rated at 260 HP at full throttle and maximum EGTs at sea level at instrument standard atomsphere, 59F, 29.92 BP at mean sea level with no humidity, that engine had 55 % power at full throttle at 13,300 feet above seal level max EGT with ISA, which is one inch of B.P. loss for every 1000 ft. of altitude above sea level and around three degrees F temperature loss for every 1000 ft. above sea level. Maybe you can come up with a math formula based off of that for a chart Avaition does have air densitity charts based on current barometric pressure at the field, observed altitude(actual feild altitude) and the outside air temps with no humidty used in figuring the density altitude I like to use the weather stations made for drag racing to read their versions of the current density altitudes

Page 415 of the Bosch Automotive Handbook, 5th edition

http://tinyurl.com/yplr3d

has the two equations you need
to see how horsepower and torque change
when either temperature or pressure change.

For temperature the offical equation
used by Americans (SAE) Europeans (ISO) and Japanese (JIN)
is:

{ Temperature Before + 460/Temperature After +460} raised to exponent 0.6

you need a scientific calculator to do this
but there is one built into every Windows computer
under Start...Accessories

As an example,
where the intake air temperature
drops to 80 degrees
when before the air coming in had been 100 degrees.

{100 +460 divided by 80 + 460} raised to exponent 0.6

={560/540} raised to exponent 0.6

= {1.037} raised to exponent 0.6

= 1.022

You mulitply this number times your horsepower or torque
so if your engine.
If your engine makes 230 hp at peak
1.022 times 230 = 235 horsepower with the 20 degree lower air temperature.

You may have heard the 'Rule of Thumb' that each 10 degree F reduction in air
temperature improves horsepower by 'about' 1% and the equation above is where
that comes from, but is more accurate

For corrections when the pressure changes
the following equation is used:

{absolute pressure after/absolute pressure before} raised to exponent 1.2

As an example
say that the weather is changing where you live
and one day the weatherman says the pressure is
29.5 inches of Mercury as a stormy "Low" passes over
then the next day a clear sky "High Pressure Area" passes over
and the pressure rises to 30 inches of Mercury

{30/29.5} raised to exponent 1.2
{1.0169} raised to exponent 1.2
= 1.0204

"Standard" SAE conditions are 29.6 inches Hg pressure and
77 degrees F (keep in mind this is actually 460 + 77 = 537 Rankine degrees)

Thanks for that info I had heard the 1%
based on 10* but never knew where it came from