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05112010, 08:37 PM  #3 
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I'm not a noob but I was arguing this point with the sales mgr here in utah. Wanted to ask the experts.
I told him I think it's about a 13.5% loss or about 360 crank hp and he says his techs have measured it at a 8% loss or about 385 hp. Last edited by Cornhusker; 05112010 at 09:04 PM. 
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05112010, 08:43 PM  #5 
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05122010, 07:53 AM  #6 
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I have worked this out to absolute 100% accuracy for my SC thread:
http://www.m3post.com/forums/showthr...=374270&page=3 Sea level pressure 1019hpa THIS IS CONSTANT You work out your air pressure at your altitude. Check with a weather staion if you dont know how At 4500 ft pressure its approx 865hpa (this can be worked out for any altitude) The percentage of air pressure at 4500ft compared to sea level is * derived by 865/1019 = 0,848 Therefore at 4500, you lose exactly 15,5% Take the factory rated power of the M3 at sea level 320 whp * 0,848 = 271,36 whp Crank HP 410 HP x 0,848 = 347HP 
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05132010, 12:13 AM  #7  
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Plug in standard condition values (i.e. the values that give "Calculated Relative Horsepower To Rated" value of 100%): Air Temperature  77F Ambient Pressure  29.235 inHg Relative Humidity  0% Elevation  0 feet Now keeping all other parameters constant, change the elevation. You'll see that the "Calculated Relative Horsepower To Rated" drops to 82.5%  i.e. indicating a loss of 17.5% due to elevation. 

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05132010, 05:42 AM  #8  
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If I use the constants and only put my altitude of 5300 ft, it gives me a calculated air pressure of 24,03 in Hg. But at my location now the actual air pressure is 25 in Hg. It also shows a 22% loss of 78% of sea level power, which is over by 34% You need to get the corrected to sea level pressure from your local air port or weather station for the day and plug that in. You also must input the humidity. When you do this it will make the percentage loss slightly less, and is more accurate to real wold conditions The easiest and most accurate method is to divide the sea level air pressure by the actual air pressure at your altitude to get your % ratio otherwise your correction formula will cause an inflated figure for sea level. In actual environment, I have a 6psi pulley on my charger but at 5300 it read 4,78psi, roughly 82% 

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