Huge dino variations...

[Paul Workman]

A while back, someone posted a source for driving hp corrections for atmospheric conditions. After running just a few scenarios, it hit me like..."Eureka!!" Since I can't seem to locate that link just now, I'll just summarize what it clearly pointed out this way:

The variables deriving Density Altitude are key...make that crutial(!!)...to the dyno's SAE corrected (calculated) hp values! In short, I saw how as little as 20º variation in temperature, along with some humidity changes, could easily skew hp readings on the same car on the same day! (20º between say 8AM and 3:30 PM on a summer day is easily possible.)

How much difference would it make? Well, w/o the calculator at hand, let me say this much: When you have your car dyno'ed, having the barometric pressure, temperature, and humidity numbers that are dialed in at that time is extremely important. 5% error doesn't sound like a lot to some, but at 400 hp, 5% is 20 ponies difference - enough to drive someone trying to set timing on camshafts nutz! (Right Pete?) But, if you have the values used to correct for Density Altitude, and the actual conditions at the time of the test, then theoretically, one could improve the accuracy - especially if the "dialed" numbers are way out, compared to conditions at the time of the run.

Maybe someone can dig that SAE correction link up again, and we could do some what if?? (cuz I gotz ta go ta woik just now!)

P.